GreenManRadio
is proud to have been awarded
the Garden Writers Association 2008 Silver Award of Achievement
for Best On-Air Talent!

Have a gardening question?
Let us help!

Send your gardening and landscaping questions to GreenManRadio.

You can also give us a call
215 989 4736 or 215 525 4736

Or drop a letter to Glen Seibert at
GreenManRadio
P.O. Box 166
2800 University Ave.,
West Des Moines, IA 50266.

We can't answer each one, but we'll sure try!

Q."I Canna Change the
Laws O' Physics, Captain!"

I’ve got some very large, tall decorative containers in my design this year, and I don’t want to fill them with huge amounts of potting soil. I’ve heard that you can fill most of a container with bulk materials like packing peanuts or even soda cans to conserve the potting soil.

-A.K. in California, by voice-mail
A.
True enough, A.K., and the same technique of putting non-absorbent filler material at the bottom of a container is often used to promote good drainage as well. Although I don’t recommend it for either use in most containers, in the case of your large, tall containers the soil physics will work to your advantage.

The theory goes that non-absorbent stuff like gravel, oyster shells, broken potshards or those Styrofoam packing peanuts, placed under a shallower layer of potting medium will let excess water run out and prevent the plants’ roots from rotting in a saturation zone of standing water. Intuitively it makes sense.

But physics aint necessarily intuitive! See, the shape of a container and the particle size of the potting medium all determine how water moves. Fine particles hold a lot of water, while coarser particles, which have more space between them, let excess water pass.

The best potting media are a balance between these fine and coarse particles, making a goldilocks mix that’s not too wet, not too dry. But water doesn’t flow well from fine textured media to coarse textured ones, like a non-absorbent filer at the bottom of a pot. It has so much space, that drainage is actually arrested. The saturation zone of the pot is driven up to the layer of potting medium, essentially creating a shallower container.

On the other hand, if you have well-balanced potting medium filling the entire container, gravity will guarantee that the saturation zone will be at the bottom, whether the container is six inches tall or 6 feet tall.

How does this affect your containers? Depending on what plants you’re going to be installing, the depth of their root systems and the amount of water they need, you can adjust the height of your non-porous filler and the depth of your potting medium to make a perfect virtual container inside the big, tall show pieces.

Just use plants with similar requirements. If their root zone is, say, 4 to 6 inches, fill your container with a foot of potting medium on top of the non-porous fillers at the bottom. You’ll have enough soil to sustain the plants with a saturation zone between the filler and the bottom of the soil layer and still not have to fill the rest of the space with pricy soil mix.

Q.Black Arts for Black Spot?
Do you have any secret, homemade brews that will get rid of fungi and other plant diseases?

-S.L. in Nebraska, by e-mail
A.
It seems almost a prerequisite these days to have some kind of arcane, sub-rosa recipes known only to "garden gurus".

I think I’ve heard of many of them, like concoctions of baking soda and soap, mouthwash, hydrogen peroxide, vinegar and even compost tea. Some just don’t work, some do but not for the reasons you’d think.

For getting rid of powdery mildew, the mouthwash formula is one cup of an ethanol-alcohol-based mouthwash in three cups of water applied once a week.

Two to three tablespoons of apple cider vinegar,
5 per cent acetic acid, in a gallon of water once a week is recommended for black spot as well as powdery mildew.

Three per cent food grade hydrogen peroxide has been used weekly both undiluted and at a half strength dilution.

And there’s the widely touted baking soda and soap spray, one tablespoon of baking soda and one or two teaspoons of real soap, not detergent, to a gallon of water.

All of them tend to work ok on powdery mildew, but then so does spraying the plant off once a week with a jet of water. If you don’t mix baking soda with soap it just blows off the plant after it dries, and it really needs to be applied to the plant before any fungal damage is evident.

Hydrogen peroxide’s chemical formula is H2O2; it's very unstable and loses that second O very quickly, becoming oxygen and water. It's great for disinfecting something immediately- it's often used on strawberries to treat them for mold before they’re shipped. But it has no staying power on plants.

Vinegar preparations have a pretty good track record at controlling black spot as well as powdery mildew, as does the mouthwash concoction. Just be very careful of the concentrations of acid or alcohol. You could end up burning your plants.

All in all the data show these natural remedies are marginal on black spot, ok on powdery mildew, but again so is a jet of water once a week. If you have really nasty infections I’d suggest trying something specifically made to go after fungus like Bravo or Daconil- or use an organic fungicide like neem or jojoba oil.

There’s also Bacillus subtilis, a soil bacterium that controls bacterial spot, powdery mildew, rust, gray mold, leaf blights and scab. And remember, the operative word here is control, not eradication. More is not better, organic or not. These may not be the nuclear chemicals used in agribusiness, but they should be used and treated with the same respect and care you’d give the heavy hitters.

Q.Not Craw... "Craw"!
I found a really odd looking growth popping up out of a mulched area of my garden. It was tinged pink to red and orange and sort of deformed looking, like a crab claw. Is this some kind of mushroom and is it dangerous?

-E.B. in Nebraska, by e-mail
A.
You’re describing lobster mushrooms- which aren’t really a kind of mushroom, they’re the result of a parasite on a parasite- a fungus called orange mushroom pimple (Hypomyces lactifluorum) that attacks other mushrooms, causing them to change color and grow into that deformed lobster claw shape.

They usually show up after rains or other humid weather and are the reproductive structures of fungi that are growing in the decaying wood of the mulch. They’re not infective of other plants in your garden, and some folks like to keep them around for the bright colors and unusual shapes.

If I had kids or pets I’d pop them out with a rake for safety sake. Otherwise, once they exhaust their food supply in the mulch, they’ll disappear.

Q.Getting Smaller Every Year
I love starting seeds indoors for my garden each year,
but it’s becoming more difficult every season to see and manipulate those tiny ones. Have some suggestions?
-D.D. in Pennsylvania , by e-mail
A.
Well, D.D., lots of us are starting to find those super tiny seeds, such as poppy, basil or carrot, more of a challenge to work with as the years go by. Fortunately most of those tiny seeds are designed to be broadcast to the soil surface rather than planted at any depth like, say, beans or peas.

I thoroughly mix the tiny seeds in with either super fine silica sand, the kind used in outdoor ashtrays, or unflavored gelatin. Put the mixture in a saltshaker or on of those cheese shakers you can get from restaurant supply houses. The seeds end up well distributed in the easy to see sand or gelatin, so when you shake a nice, even coat over the soil surface, you can be confident of getting uniform application of your tiny seeds.

I also press the stuff firmly into the soil surface to get good contact with the seeds, and if the seeds need light to germinate, such as lettuce, I add a very light layer of vermiculite. This protects them and keeps moisture in the soil. For seeds that need darkness to germinate, such as parsley, I’ll add enough soil mix to completely cover them.

Q.Blowng Hot or Cold?
I’m just getting started with vegetable gardening from seed and don’t quite get some to the terms the old timers throw around, like “warm season crops” and “cool season crops”. What does that mean- the season you plant them in, the season they grow in, or something else entirely.
-G.L., Oregon, by e-mail
A.
“Warm” or “-cool season crop” is a kind of shorthand for the weather and environmental conditions the plant likes to grow in. But that also gives you a lot of information about the right conditions for planting and germination, soil moisture, light, all those things.

For example, cool season lettuce is best planted in early spring or fall, when the air temperature is lower. The soil temperature doesn’t need to be as warm for them to germinate and they don’t need as long a day period as, say, cucumbers, which need both warm soil and air temperature and a long day period with more intense light.

The “season” a plant likes to grow in also give you a hint about which ones can be interplanted for maximum yield in a vegetable garden or to keep color in an ornamental garden bed- some developing quickly in the early season while others take more time and come into their own after the early guys have gone by.

Cool season vegetables include beets potatoes broccoli onions cabbage peas carrots radishes cauliflower spinach collards turnips of course lettuce.

Warm season veggies include beans, peppers, cantaloupe, squash and pumpkins, cucumbers, sweet potatoes, eggplant, sweet corn and tomatoes.

For a really in depth lesson on the seasonality of plants and interplanting, check out Carrots Love Tomatoes: The Secrets of Companion Planting for Successful Gardening by Louise Riotte or Square Foot Gardening by Mel Bartholomew. They each have excellent explanations of the envionmental variables plants need and how to use that to maximum effect in the garden.

Q.Avoid A Fishy Environment
I'm getting ready to landscape a koi pond and waterfall my husband installed last fall and I have a good idea of what I want to plant. But I've listened to you talk about designing the whole ecosystem of a landscape and not just what looks pretty. With that in mind are there any plants I shouldn’t install around this water feature.
S.L., Oklahoma, by e-mail
A.
Thanks for such a good and timely question. Now is the prefect time of year to be thinking about plants for a spring landscaping project.

The leaves, flowers, bark, seeds or roots of these plants can definitely cause some problems and should keep their distance from a water feature with fish:

Azalea (Rhododendron spp.) Black Locust (Robinia spp.) Buttercup (Ranunculus spp.) Caladium (Caladium xaiitliosoma) Castor Bean (Ricinus communis)

Chokeberry/Cherry (Prunus spp.) Climbing Nightshade (Soanum dulcamara) Jack in the Pulpit (Arisaema spp.) Angel’s Trumpet (Datura spp.) Lily-of-the-Valley (Convallaria majalis) Pigweed (Amaranthus spp.) Red Maple (Acer rubrum) Sweet Pea (Lathyrus spp.) Flowering Tobacco (Nicotiana spp.) Tomato (Lycopersicon esculentum) Yew (Taxus spp.) Oleander (Nerium oleander) Oak (Quercus spp.) Russian Olive (Elaegnus angustifolia) Black Locust (Robinia pseudoacacia) Snow on the Mountain (Euporbia spp.) Hellebor (Helleborus niger) Lantana (Lantana camera) Lily of the Valley (Convolaria majalis) Solomon's Seal (Polygonatum spp.) Morning Glory (Ipomoea spp.) Dwarf MorningGlory (Convolvulus spp.) Fritillaria (Fritillaria spp.) Stonecrop (Sedum spp.)

Q.Frozen Fish?
Last winter all the fish in my water garden died. I was told if the pond was deep enough the water wouldn't freeze and the fish would be ok. What happened?
N.M., Minnesota, by e-mail
A.
The ice didn't do your fish in directly, but it was the cause of your losing them. Even in the winter, organic material is decomposing at the bottom of the pond... stuff like leaves and fish waste.

This decomposition generates toxic gasses, and when a water feature freezes over the solid layer of ice traps these gasses and prevents them from leaving the water.

First, try to keep leaves and other organic material out of the pond by putting netting over the surface of the pond. That ½ inch square netting used to keep birds from taking fruit off of fruit trees works well. Large rocks or bricks can hold down the edges of the netting while the leaves are falling.

Then use a skimmer or water-pressure powered vacuum to suck the stuff from the bottom of the pond before you wrap it up for the winter. Then, put an electric pond deicer or live stock water tank heater and float it in the pond. It will keep a small area of the pond's surface ice free and open to let gasses vent and oxygen into the water.

Q.Fuming Over Greenhouse Gas
I have a small hobby greenhouse that I heat over the winter with an unvented propane space heater. I'm concerned that the fumes are hurting my plants. Should I be worried?
M.H., Washington, by voice mail
A.
If you're using the kind of little space heater I'm thinking of, which burns a tiny amount of propane and is designed to be operated unvented in occupied rooms, there won't be any permanent damage to your plants.

The blooms of tropicals might fade and drop a little sooner than normal, but the other plants you're holding in your greenhouse shouldn't be effected.

Just for safety sake I'd get a carbon monoxide detector and install it in the greenhouse so you'll know if any CO is present before you go in.

That' a good idea for key areas of your house, too. I have a CO detector installed right next to each of my smoke alarms.

Q.Chilling Tulips are Blasted
Every year I chill pots full of tulip bulbs in the garage refrigerator, and the flower buds form but don't open. What's happening?
T.S. from Fulton Missouri, by e-mail
A.
Your tulips are experiencing bud blast... They shrivel up before they open.

I'll bet along with the pots full of tulips you're also storing some fruits or vegetables in that fridge. They emit a colorless, odorless gas called ethylene that causes them to ripen and, ultimately, spoil. This ethylene gas also blasts the tulips.

Once the bulbs have been damaged you have to throw them away. Put pots full of fresh bulbs in plastic bags, checking them frequently to make sure they aren't getting moldy.

You might also want to look into some of the ethylene gas absorbent products on the market and put a pouch or two in the fridge. Better yet, because you live in a region of the country that gets nice and cold, chill your tulips in an outdoor cold frame or in an unheated garage, completely away from stored fruits and veggies.

Q.A Case of Mistaken Identity
I've grown Peruvian daffodils in other gardens in the past, but this year they weren't nearly as fragrant as before. What am I doing wrong? very year I chill pots full of tulip bulbs in the garage refrigerator, and the flower buds form but don't open. What's happening?
B.L. from California, by e-mail
A.
Likely nothing. It might just be a case of having planted the wrong bulb.

You probably had Pamuanthe peruviana, which is very fragrant, in your old gardens. This time you could be growing Hymenocallis narcissiflora, which is in the amaryllis family and not nearly as sweet smelling.

Both are called Peruvian daffodils, and both like the same conditions, full sun and moist, well-drained soil. Both have the same dark green, strap-like foliage. But the hymenocallis is also called the spider lily because of the huge 4 inch curled petals that surround the white flower cup.

The Pamianthe has much shorter petals that aren't curled. Check out the photos at right to see what I'm talking about.

I'd recommend getting in contact with some of the specialty growers on line and make sure you're getting the right bulb by ordering it with the latin names.

Q.Black Oil Sunflower Blues?
We feed wild birds black oil sunflower seeds. But I've heard the hulls will ruin our compost. What's the story?
R.H. from Tennessee, by e-mail
A.
Black oil sunflower seeds are terrific for wild birds. They have high energy content and the thin shells are easy for little birds like chickadees, juncos and sparrows, as well as doves, to crack.

But as the hulls decompose in the compost pile they exude a substance that inhibits seeds from sprouting.

You may want to switch to hulless sunflower seeds. They're as easy for the little birds to eat as black oils, and they frankly make less of a mess.

If you'd like to stick with the black oil sunflower seeds, instead of composting them, put a cup of the hulls in 4 cups of water and puree in a blender.

Then pour the slurry into the cracks of the sidewalk, along the fence line and anywhere else you'd like to keep free of weeds. It makes a great preemergent weed blocker

Q.Too Late for Fall Bulbs?
How late in the season can I plant bulbs?
J.T. of Oregon, by email
A.
You really should get bulbs into the ground 6 weeks before the ground freezes in your area.

They need that time to start developing the tiny feeder root hairs that will establish them in the soil. But they mustn't go in so far in advance of a freeze that they think its spring and start emerging.

If you are a little late for the deadline, don't worry. You can keep planting bulbs up until the ground freezes too solid to dig.

Just be sure the bulbs aren't too old and soft from having waited so long. Better to get them in the ground than lose them for sure if you don't.

Cover them with a good thick layer of mulch to keep give them a little more development time before the ground freezes.

And be sure to rake the mulch back in the spring so the emerging plants won't have to push their way through it.

Q.Pruning Hydrangeas for flowers
My hydrangeas are done & turning brown. When & how is the best time to prune or deadhead? This plant is all new to me.
A.G. in Minnesota, by e-mail
A.
The first step is to determine what type of hydranges you have. The two most popular types have different needs.

Mophead and Lacecap hydrangeas (the macrophyllas - usually shades of pink or blue) don't have to ever be pruned back unless they're really old. And then, removing dead stems must be done for the health of the plant and can be removed at any time. Removing individual dead blooms (deadheading) can also be done at any time.

Macrophyllas bloom on "old wood", that is, stems that have been on the hydrangea since the summer before the current season. Theyre producing next year's flower buds now, and will be though October. If those stems are pruned in the fall, winter, or spring, there will be little or no bloom the following summer.

Being up in the colder region of Minnesota, it's possible you have one of the more cold tolerant 'remontant' or "everblooming" hydrangeas. They set a second set of flower buds if the first ones are killed by cold temperatures or pruned off, and so will flower no matter when you prune them. 'Endless Summer' is one of these everbloomers.

But for the vast majority of hydrangeas, pruning after July will likely result in few if any blooms.

Arborescens and Paniculata hydrangeas

Another pruning method is used for Arborescens types (the Annabelles ) and the paniculatas (PeeGee types). These hydrangeas bloom on "new wood", stems that developed on the plant during the current season.

These guys are a pleasure to grow because they are bound and determined to bloom every year no matter how badly they're mistreated! The only time they can't be pruned is in the spring for the Annabelles and the summer for the PeeGees. Naturally they can also be deadheaded at any time to keep the plant looking neat and fresh.

No matter which kind you have, all the dead stems should be removed from hydrangeas every year. Cut them back all the way to the ground.

After the plants are at 5 or more years old, 1/3 of the older stems should be removed each summer, also all the way down to the ground. This will revitalize the plant and keep its shape and structure open and well-formed.

If it's necessary to prune a plant to reduce its size, you can cut it back in June or July without harming the next year's bloom. But keep in mind it will return almost immediately to it's former size. This is one reason why it's best to plant a hydrangea where it does not have to be pruned.

Q.Lily Out of the Valley!
I've planted Lily-of-the-Valley at the edges of my patio and walkways and it's been lovely for years. Now all of a sudden it's taking over my yard. How can I bring these surprise invasives back under control?
E.G. Middleriver, MN, by voice-mail
A.
This fragrant spring bloomer (Convallaria majalis) has fooled a lot of gardeners over the years. You think its spreading slowly if at all, then suddenly its all over the place.

That's because it is constantly sending out underground runners that in turn produce new growth nodes and root clusters. The new shoots seem sparse until those nodes make nodes, ad infinitum!

Fortunately the root system is very shallow. You can probably just pull up most of the offending strays without hurting more deeply rooted plants. Try removing the mulch from invaded areas for a while and let the soil dry out. This will end the moist, cool conditions that promote rooting and spreading.

Q.Embalming Hydrangeas
I have some gorgeous hydrangeas and I want to dry the flowers for arrangements. But they get brittle and impossible to work with after they're dry. What can I do.
B.C. New Holland, PA by e-mail
A.
Preserve them with glycerine. What you'll be doing is more or less embalming the flowers by replacing the water in them with the glycerine. This will preserve them without drying them out and making them brittle.

Gather your hydrangeas as soon as the flowers are fully open by cutting the stems at a 45 degree angle. Mix up 2 parts of boiling water with one part glycerine, which you can get at the drug store.

Pour about 6 inches of the mixture into a container and stand the hydrangeas in it and let them soak for up to a month or more. The embalming is finished when little droplets of glycerine start oozing out of the edges of the leaves or the petals of the flowers.

Now those beautiful hydrangeas will stay supple and beautiful all winter!

Q.Tarnished Silver on the Porcelain
I planted a variegated porcelainberry vine (Ampelopsis brevipedunculata ‘Variegata') this year and I'm not seeing any variegata. The leaves are all solid green. They're a beautiful healthy dark green, but where are my pretty silver leaves?
G.H. , Marrion, OH by e-mail
A.
The key to this is your having just planted the porcelainberry. Your vine is in a heavy new growth phase. The leaves are all green because they're loaded with chlorophyl to support this juvenile new growth.

Once the vine is established and doesn't need so much chlorophyl you'll start to see that beautiful variegated silver foliage start shining through.

Q.Signs of Troubled Soil
My friend is talking about the white clover in my lawn being an "indicator weed." He says it means my soil is too wet and not fertile. Does he know what he's talking about?
G.K. of Oregon, by e-mail
A.
He sure does! Indicator weeds are a great tool to let you know the condition of your soil.

It's part of their survival strategy to find the less-than-perfect conditions in which other plants won't do well and take over.

They can tell you that you need to improve your soil's structure, texture, nutrition or chemical composition.

White clover (Trifolium repens) loves wet but infertile conditions. I'll bet there's some red sorrel (Rumex acetosella) around too, since it loves the wet, acidic Oregon soil. Check the table below for several kinds of indicator weeds and the soil conditions they thrive in.

Q.Counting Down the Time
What do those days-until-harvest numbers on the seed packets really mean? Is there a difference between those direct sown into the garden and those started early in flats?
F. T from Ohio , by voice-mail
A.
"Days until harvest" is an average of how many days it takes from the time the seed is planted until you can harvest fruit.

It gives you an idea of which varieties are right for your garden. If you're down south you can select varieties that need more time to mature, if you're a northern gardener you can select varieties that need a shorter growing season.

It's also a great way to extend your harvest. Say one variety takes 45 days to mature and another takes 70 days. You can count on three weeks between harvesting. Staggering the maturation dates can give you fresh produce all season long.

If you've planted things like tomatoes, broccoli, peppers and cabbage indoors in seed starting flats, the days to harvest time is calculated from the day they're transplanted into the garden, not from when you first sow them into the trays.

Q.Hot Stuff to Chase the Bugs
I've heard of hot pepper sprays and waxes repelling deer and rabbits, but how about insects? Can I use them to keep the bugs off my garden?
T. C. from Nebraska , by e-mail
A.
The active ingredient in today's hot pepper sprays is Capsaicin, the same stuff that burns like fire when it comes in contact with our tongues.

Studies back in the early 90s did show that the compound repels insects, including whiteflies and mites, for about 2 months in the controlled environment of a greenhouse. It'll probably last substantially less time outside, but it's sure worth a try.

There are many commercial products with capsaicin, but if you want to make your own hot pepper spray, puree 1 or 2 cups of habanero peppers in a blender, mix with 2 cups of water and strain the liquid. Add 2 tablespoons of liquid soap as a sticking agent and spray the stuff directly on the plants.

Tests show that capsaicin won't harm the plant tissues, but the soap might, so test it on a small area of one plant first. Be sure and use gloves-capsaicin can irritate your skin.

And don't touch your eyes or other mucous membranes before you wash thoroughly! This stuff can really damage your eyes.

Q.Mildew Magnets
What can I do to avoid getting powdery mildew on my lilacs and zinnias? They end up getting covered with the white dust every spring.
E.H. of Illinois, by e-mail
A.
There are several plants that just seem to attract powdery mildew like a magnet, and you have the top two. Others include beebalm, phlox and roses.

In order for the disease to flourish, three things have to be present: A pathogen, a susceptible plant and the right environment. Remove one or more parts of the "disease triangle" and you've solved the problem. In your case you can remove all three.

First, choose a nice sunny spot that gets plenty of air circulation for any susceptible plant. One big no-no is to install these plants too close to a foundation or wall. You need to have free circulation of air around them. Removing old leaves in the fall helps get rid of disease organisms, too.

Next, spray a ten percent baking soda solution, beginning in the spring at bud break and every ten days to control the fungus that causes mildew on lilacs.

Remember to add some mild liquid soap, not detergent, or light vegetable oil to help the baking soda stick. Tests show that soda without a sticking agent doesn't last long enough on the foliage to do much good.

Both baking soda alone and in solution with soaps and oils can burn plant tissues, so test in an inconspicuous spot to make sure your target plant won't suffer more harm than good.

Finally, consider the many disease-resistant varieties of lilac such as Syringa vulgaris ‘Blue Skies'® and the zinnia ‘Profusion' series.

.

Q.Finished Forsythia
My Lynwood forsythias are taking over my shrub border. They root everywhere they touch the ground. How can I remove them and what would be a good, spring-flowering replacement?
G.K. of Iowa, by e-mail
A.
You don't see too many of them, but well-grown forsythias that have never been pruned back are really something special to see. The arching branches of these fountain-like shrubs have tons of lemon yellow flowers in very early spring. In fact they're often used as a touch stone for the beginning of the season.

But because they do become quite large and tend to get cut back frequently, they lose their natural shape and the flowers that bloom on old wood. They often end up pruned into a stiff oval with a fringe of flowers only around the base.

Remove your ‘Lynwoods' by digging them out, then increase the organic matter in the soil by adding well-rotted compost. Kill any suckers or rooted portions that you can't dig up by applying Roundup or another woody plant killer.

Cut the stems after bud break in the spring and immediately paint a coat of Roundup to the cut surfaces with a small brush.

Two underused shrubs that bloom beautifully in the spring are cornelian cherry (Cornus mas) and a cultivar of common pearlbush (Exochorda x macrantha) called ‘The Bride'.

Cornelian cherry is offered as a single stemmed small tree, or a multi-stemmed shrub. It bears small, yellow flowers very early in spring, beautiful, shiny green leaves and glossy red berries that are relished by birds.

Pearlbush (‘The Bride') is a slow growing shrub that develops into a 4 foot by 8 foot mound. The flowers appear like large pearls along the stems in April with lower ones opening up like apple blossoms. Pearlbush looks like any green shrub for the remainder of the year, but the fresh white flowers are quite stunning in spring.

.

Q.Where to craft the graft
I'm planting some self-fruiting, grafted peach trees this year. Should I treat them any differently from other trees? How deeply should I plant from the graft union?
B.F. from Washington state , by e-mail
A.
Plant your trees with the bottom of the graft union about 2 inches from the soil level. If the union is planted in the soil it could send up suckers which will be different from the desirable tree that was grafted onto this rootstock.

If the union is below soil level it could rot. Planting a little too shallow is better than too deep, but in any case be sure to get those roots covered.

If they're exposed they'll dry out and weaken the tree. And since you're way up in Washington state you'll probably be ok with planting a peach this late in the season. They need to go in the ground while they're still dormant, and that's traditionally in December through February. Where as if you lived in the warmer climates, early winter is the better time to plant fruit trees.

Q.Softsoaping Insects
I'm getting a head start on insect problems this year, and I want to take a more organic track. Is there a home recipe for insecticidal soap that's as effective as the commercial products?
D.K., New York, by e-mail
A.
The old standby is one teaspoon of pure, unscented, liquid soap, not detergents or antibacterials, in a quart of water.

The soap cuts the insect's waxy coating, called the cuticle, and they dry out and die. Soft bodied insects like aphids are more susceptible than, say, beetles, which have a hard, water-proof shell.

But plant leaves have a waxy cuticle too, and soap can remove it just like it can the insects', allowing the plant to lose moisture, scorch, drop leaves and possibly die.

Test your mixture on a small area of one plant to make sure it doesn't burn the foliage. Even if it appears safe, don't lavishly drench the entire plant. Use a hand sprayer to apply the soap solution only on the insects directly.

And remember homemade insecticidal soap doesn't work once it's dry, so you'll have to reapply every day or two.

Q.The Gravity of the Situation
I had a number of potted plants rot last year from saturated soil. Should I add even more non-porous material in the bottoms of my containers for better drainage?
G.,W., California, by e-mail
A.
It goes against popular wisdom, but loading stuff like oyster shells, shards of pottery or heavy pea gravel in the bottom of a container doesn't promote better drainage. Drainage is about the physics of soil volume, water-holding capacity and gravity.

First, water doesn't flow easily from a fine textured media to coarser material. So after gravity pulls out its share, water tends to stay put in soil.

Also, if you fill a container with nonporous material you make it more shallow in relation to its diameter. Soil added on top of the material forms a wide, thin layer.

True this layer will contain less total water, but it will hold that water more tightly against gravity than the same amount of soil in a tall, narrow cylinder, the way snow shoes support a 250 pound man walking on fresh powder that would swallow him in ordinary shoes.

Instead of compounding the drainage problem with stuff in the bottom of the pot, amend the soil by mixing it with perlite, available at nurseries and garden centers. Or better yet, replace soil with a sterile, soil-less potting media.

Q.Staunching Oozing Icemilk
I have a large, older potted African milk tree I want to prune. Is there away I can stop it from oozing "milk" where it's cut?
T.G., Minnesota, by e-mail
A.
Your African milk tree (Euphorbia trigona) is really a cactus that can slowly grow to 12 feet tall. So pruning it back as a houseplant makes sense.

To staunch the flow of milky white sap, hold a piece of ice directly on the cut surfaces. The cold constricts the tissues and closes the wound. Then gently wipe the excess sap away with a wet cloth.

The sap of all euphorbias is toxic and irritating to the skin and eyes. Wear rubber gloves and wash thoroughly after you've handled it.

To get more milk trees, let the portions you cut off dry in a shady place for about 10 days to form a callus over the wound. Then press them into moist, sterile potting soil, water thoroughly and keep them in filtered shade for about six weeks to take root.

Q.Sawdust Mulch
I'm a woodworker as well as a gardener, and I make a lot of sawdust in the shop. Can I use this for mulch?
O.G., Maine, by e-mail
A.
It's not the best idea to use fresh sawdust as a garden mulch.

The natural bacteria in the soil will break it down like any organic product, and in the process use up a lot of nitrogen that should be going to the plants.

Instead, add the chips and saw dust to the compost pile and let it cook for a season.

And if you work with tropical woods like cocobolo, padauk, or even ordinary walnut, keep those shavings out of the compost all together. They're toxic to other plants.

Q. What Is Green Manure
I'm starting to get serious about growing vegetables in an organic garden, and I've been hearing a lot about green manure lately. What it is and how I can use it?
K.L., Oregon
A.
"Green manure" is plants that are intentionally grown to be tilled back into the soil to improve it. It acts as an organic fertilizer and soil conditioner and helps your garden soil in several different ways:

First, a good heavy over crop chokes out weeds that could get a foothold in garden soil that's otherwise lying bare.

Then, there are cover crops like winter rye, annual rye and buckwheat that are good at stabilizing the soil to prevent erosion from water runoff.

As an organic fertilizer, legume cover crops like clover and winter vetch take nitrogen from the air and turn it into a form plants can use. When you turn them under you return this nitrogen to the soil.

And they all improve soil texture by breaking down and adding organic matter, which is always a good thing!

Sow your cover crop and allow the plants to grow for an entire gardening season. That's usually through the fall in cooler climates and the winter in warmer locations.

In spring time, cut the plants and rototill them into the soil. Give them a few weeks to break down before planting the spring crops.

As always, check with your local extension service to find out the best crops to use and when to plant and till them. And thanks for going organic! Good luck with your veggies!

Q. Will A Zinc Sink Stink?
Next question comes from K.G. in Texas. Im going to install a water feature in my home garden this year and I want to give it a country theme and use a watering trough for the pond. Will the galvanized stock tank hurt my fish?
K.G., Texas

A.
It certainly could. That galvanized, rustproof coating is made of zinc, which could be released into the water by chemical action.

Still, you can use a stock tank to keep your design theme. Just line it with a good, heavy pond lining material, available from garden centers that sell pond supplies. Or, you can paint the inside of the tank with a special coating material made just for ponds. Check out these websites for on-line suppliers for both of these products:

http://www.justliners.com

http://www.pondbiz.com

Q. Contaminated Compost
I've heard municipal composts made and distributed by cities can damage home gardens. Should I stop using my city's free compost?
J.V., California, by voice mail

A.
Lots of cities use weed and feed products on municipal parks, ball fields and other turf. They're full of herbicides to kill broadleaf weeds.

When communities recycle these clippings, along with home yard wastes, the compost gets contaminated and could stunt or even kill your ornamentals and get taken up into your edibles.

Even a hot compost process can't get rid of chemicals and some diseases. I'd use an organic, chemical free compost, especially on the vegetable garden, just to be on the safe side.

Q. Don't Paint When You Prune
I'm going to remove the limbs of some trees soon and I've heard that painting the wounds helps them heal faster. If so what kind of paint should I use?
J.C., New York
A.
According to every arborist I've ever spoken to or trained with, this idea of painting the open wounds on freshly pruned trees actually causes more harm than good.

When a tree is wounded, either naturally or by pruning, the damaged tissues compartmentalize- that is, they start sealing off the damaged as soon as it happens. Painting this wounded tissue actually slows down or stops the compartmentalization process and keeps the wound open.

A better way to be sure your trees remain healthy after pruning is to make the cuts properly.

Start the first cut a foot or two out from the trunk. Cut the underside of the limb about halfway through. This creates a break in the bark and wood so that if the branch gives way the bark won't be peeled off away from the limb and maybe even down the trunk of the tree.

Make the second cut about six inches further out from the trunk. This cut starts on the top side and goes all the way through the limb. By cutting from above, the weight of the branch will cause the groove being cut by the saw, the kerf, to pull open and keep the saw from binding.

After the major weight of the limb has been removed, make the final, surgical cut, just outside of the collar flare- the cone-shaped swelling right where the base of the limb met the trunk.

Don't try to cut flat up against the trunk. Leave enough of this stub intact so that there's flare tissue all around it. Take a look at these photos of some well cut and poorly cut limb stubs. The cuts made correctly have that "doughnut" of bark-like wood, the callus, that's formed completely around the cut area. This surrounding callus will heal over and eventually grow new bark and scar tissue to seal the wound.

Q.Choosing a Professional Arborist
I want some of my older trees pruned or removed altogether. I've gotten some bids from local professionals, and of course I want to pay the lowest price, but I know it's never that simple. How should I choose?
K.S., California
A.
First, you're already on the right track by taking responsibility for becoming an informed consumer. You're wise to get a number of bids. Price is a factor, of course, and you usually get what you pay for.

But there's much more to hiring an arborist than just the budget. Some big arbor projects just need to be taken care of by professionals.

Removing trees is one of them, simply because of the tremendous work it will take to break down and haul away the lumber. Not to mention all the dangerous climbing, hoisting, roping and falling timber!

Pruning is less labor intensive by comparison, but it still requires great expertise to be done right. A badly pruned tree may take years to recover, if it can at all.... and it will never be the same

First, never hire "door-knockers". Reputable, certified arborists are too busy doing top-notch work to be out trolling neighborhoods for jobs.

Make sure the arborist belongs to a professional organization. Membership in the National Arborist Association or the Society of Consulting Arborists demonstrates the company's willingness to keep abreast of the latest trends and research.

Ask if they have a Certification from the International Society of Arboriculture. Passing their extensive Certification Exam means the arborist is an expert in all aspects of tree care.

Always ask for plenty of customer references, and follow up on them. Were the customers happy with the contractor, not just in the work but in their overall professionalism and customer service.

Take a drive and look over the landscapes where the company has done work, and talk to the homeowners to see if they are satisfied.

Demand proof that the contractor carries an up to date license, bond and adequate insurance for personal injury and property damage, and call his carrier to see if there have been any claims against him.

Do your homework. After the arborist tells you what needs to be done, research his recommendations to see if they're valid and reasonable.

For example, if he suggests a tree needs to be topped, run away! No reputable arborist will recommend topping and, personally, I believe he has a duty to try to talk you out of it if you ask him to do it.

I've seen unscrupulous contractors, and ignorant city work crews, indiscriminately "hatrack" or "head back" a tree like merciless butchers. Usually its done under the excuse that the tree is too large for the property or it's interfering with utility lines or creating safety hazards. But its all just systematic mutilation that usually causes more problems than it solves.

I've even know of an unscrupulous contractor that would top trees to induce lots of little branch stubs and suckers which he could then return to prune off year after year.

The International Society of Arboriculture's Certified Arborists Directory will let you research arborists for your area by zip code.

Q.Japanese Invasion?
Id like to get some of that beautiful red Japanese bloodgrass in my garden this year, but I've heard its an invasive plant here. True?
T.L., Kentucky, by e-mail
A.
There are opinions from both sides of the isle on bloodgrass. It's a cultivar of Imperata cylindrica, congograss, which is so invasive it's on the governments Noxious Weed list.

But so far ‘Rubra', the red cultivar we call bloodgrass isn't considered a rampant spreader. I have a patch in my Zone 5 garden outside the little studio on the hill, and the clump has never gotten any larger than when I planted it.

Just to be safe, I'd plant it where it will be contained, pull any green shoots before they have a chance to become established and cut off the seed heads, which could spread and revert to produce the all green plants that could become invasive.

Q.Sneeze-free Tree?
I want to plant some trees in my yard this fall, but my daughter is very allergic to pollen. Are there some nice looking trees that won't send her into sneezing fits?
E.W., Minnesota, by e-mail
A.
There are all kinds of great landscape trees that can peacefully coexist with your daughter's allergies. The key to finding them is to understand a little bit of tree biology.

There are three kinds of flowers: Male, Female and "Perfect." The first two are obvious. And perfect flowers contain both male and female parts together in each flower on the tree, see the photo top right. Since their pollen doesn't have to travel very far they don't usually cause too many allergies.

There are also two kinds of trees: Monoecious and Dioecious. Monoecious trees have separate male and female flowers on the same tree. While they're still relatively close together, the male flowers do put out a lot of pollen. Oak and cypress are monoecious and put out enough pollen to aggravate some sensitive folks.

Dioecious trees have all male or all female flowers on different trees. Males depend on pollinators, like bees, and on the wind to carry their pollen to distant female flowers. It's this wind-born pollen that causes so many people, like your daughter, to suffer during the flowering season.

Good "sneeze free" trees you could install in your yard include firs, cedars, the strawberry tree (Arbutus unedo), female ash, Chinese fringe tree, junipers, podocarpus, poplar and willow.

Trees to avoid include acacia, birch, beech, liquidambar, mimosa, olive, pecan, walnut and sycamore.

You also can't go wrong with fruit trees suh as peach, cherry, flowering crab, avocado, plum, nectarine, persimmon, almond and pear.

I hope your little girl's next year is sneeze free!

"Perfect" apple blossom flower has both male and female parts in the same sturcture


Peach (Persica spp.)


Cherry (Prunus spp.)

Flowering Crabapple (Malus spp.)