Common Questions from the Garden
answers to a few of the most frequently asked gardening questions
by Ruth S. Foster
I am often asked similar gardening-related questions several times. Over the years I have made note of these questions hoping to create a resource such as this. Here then are a few of the most commonly asked gardening questions and my thoughts as to their solution. Enjoy!
Bird of Paradise Tree
Question: What is a 'Bird of Paradise' tree?
Answer: It's an ornamental tropical plant that grows into a small tree about 30 feet tall. The large leaves resemble those of the banana while the big, spiky, white and blue flowers look a little like a bird in flight, hence the name. It's close relative, the (plain) 'Bird of Paradise', a 3 to 5 flowering plant with exotic looking orange and blue spiky flowers. Botanical name is Strelitzia.
Perennials Looking Poorly?
Question: What can I do to perk up straggly looking old perennials?
Answer: In spring, try some organic fertilizer to improve the soil, and a top dressing of about an inch of compost. Well-rotted manure often does wonders. Some may have become overcrowded and need dividing. If they don't bloom, dig them up and divide them in late summer or early spring. Replant the vigorous young shoots to renew and increase the number.
Cold Tolerant Annual
Question: What is a cold tolerant annual to plant very early in spring?
Answer: Pansies are best, they go well with flowering bulbs and last until the heat of summer.
Question: Branches on my dogwood tree are dying and the bark is loose. Should they be cut off and should anything be put on the cut? Is this a nutrient problem?
Answer: It's not a nutrient problem. Dogwoods get a devastating fungus disease call anthracnose. Infected leaves get brown blotches, then dry up and hang on. It spreads to branches, and eventually can kill the whole tree. It thrives in dampness and wet weather.
Dead branches can be cut off, ideally in summer. It should be done during dry weather, and the pruning shears or saw should be disinfected in alcohol or bleach between cuts to keep from spreading the disease. The current theory is to not paint wounds or put anything on the cuts.
Trees with good air circulation, particularly in sunshine, do better because the leaves and branches dry off. Keep dogwoods well watered in summer by running water on the ground over the roots, but don't wet the leaves.
Also mulch under the drip line. Fertilize in the fall after the leaves have turned color.
Although some branches die, the trees may continue to bloom for many years. I have an infected tree that's been hanging in for about 15 years, and when in full flower, it's still is a joy to see.
Kousa dogwoods (which bloom later) are less susceptible to anthracnose than our native American dogwoods. Some new resistant hybrids have been developed at Rutgers University, and are for sale if you ask.
Dogwood Varieties Resistant to Anthracnose Infection
Question: Are there any native May blooming dogwoods, like Cornus florida, that don't get the anthracnose fungus that is killing so many of my older ones?
Answer: One old favorite white one, Cornus florida 'Cherokee Princess', is resistant. Also several new varieties from Rutgers University called the "Stellar" dogwoods. They're a cross breed between C. florida x C. kousa, and bloom just as the old favorites are finishing, but before the kousas begin. Stellar clones named 'Stardust' and 'Ruth Ellen' are white and branch horizontally, like old dogwoods. More upright and vase shaped, like the kousas, are white 'Galaxy', 'Aurora' and 'Constellation', also 'Stellar Pink'. They are more vigorous and grow faster than either C. florida or C. kousa. Because these have oriental genes, the dogwood borer is less likely to attack them. Planting dogwoods in sunlight and giving them good air circulation helps retard the fungus. It's always worse in years with wet weather.
Question: I have seen mulch that is dyed. Does this hurt the plants?
Answer: No. It's only water-based paint though it's made especially for spraying on mulch. Many landscapers use it to freshen up gray faded looking mulch.
American Elms and Dutch Elm Disease
Question: I would like to plant an old fashioned American Elm. Are there any ones that are resistant to fatal Dutch Elm Disease?
Answer: Recently, the United States Government has released two new American elm cultivars (one is called Valley Forge Elm) that are the most resistant known to date. All others that claim to be resistant are not. Other varieties such as Chinese elms and English elms may be somewhat resistant, but they do not have the beautiful spreading elm shape. Genetic research is ongoing to identify the resistant genes. Dutch Elm Disease , a fungus infection carried by the elm bark beetle, was brought into this country 75 years ago in some lumber from Holland. Since then, it has spread from the East eventually killing almost every American elm in its path, and is currently decimating the Midwest in it's relentless trek westward. Sometimes trunk injections are given to very valuable trees to stop or prevent the fungus but most trees just die. The American elm was a much loved tree because it was easy to grow, fast and had a beautiful vase shaped crown. The original Liberty Tree which the British cut down on the Boston Common in 1775 just before the American Revolution was an American elm.
When to Plant Grass in Northern Germany?
Question: When should I plant grass seed in Northern Bavaria and what is the best temperature for growing grass?
Answer: First read the article Pursuing the Perfect Lawn, in Gardens for Guys. Then figure out when it is early fall and when it is mid-spring in the part of Bavaria you live in. Buy grass seed locally for your area, usually a variety of fescue grass.
Question: Where are the gypsy moths? We had epidemics a few years ago and now they seem to have vanished.
Answer: They are around as usual in June, but when there are not be many, you just don't notice them. They have a population explosion cycle about every l0 years. In between pockets do remain just waiting for the right weather conditions to favor an increase in their numbers. In some places, like Massachusetts, they seem to have become susceptible to diseases that kill them when they start to increase. If you see a gypsy moth hanging dead from a tree with his back legs hanging on but his front end collapsed in the shape of a V, it has the disease. Leave him there to spread it to the other caterpillars. (People don't get it.)
Installing Stone Edgings
Question: I want to install a decorative concrete block around a planting bed. It looks simple, but I would like some pointers and a how-to book.
Answer: It isn't too difficult. The main problem is digging deep enough to put in a proper base that will provide good drainage and not heave in freezing weather. Usually sharp builders sand is used, occasionally stone dust. Here's one trick to help get an aesthetically pleasing line. To get a fine curving shape, first lay out a garden hose and adjust it until it's looks good, then use the hose as a marker of where to dig. To get a perfect circle, anchor a string to a stake. Then using that as the center, move the string all around and mark the earth well as you go around. For straight lines, always use a board or a well anchored taught string. There is nothing worse than doing all the work and then finding out it's crooked. Ortho Books and Sunset Books both have some good masonry manuals. Some of the stone and concrete companies have small instruction flyers. Be sure to choose attractive edging materials. Common ones are brick, cobblestone, fieldstone, pre-cast decorative blocks, as well as more expensive granite and bluestone.
Keeping Animals out of the Garden
Question: How can I keep animals such as rabbits and dogs out of my garden?
Answer: To discourage animals from eating plants, one can do a variety of things such as:
Grow poisonous plants, many of which are quite attractive. Most taste bitter so animals won't eat them.
Repellents are another possibility. Among them, a bitter tasting fungicide called Ropel or Thymol often discourages nibbling, especially if applied before the animals become used to eating certain plants. (Allow it to dry, then apply a second coat.) It may cause damage to tender new growth, so test first on a plant or two.
Another dog and cat deterrent is methyl nonyl ketone, which has to be reapplied to the ground every week or so. It's poisonous so always wear gloves when touching it. And never use it where there are children.
Old wives' tales advise a bunch of hokey combinations of household items ( like mothballs) and chemicals and strange things (like human hair hung in pantyhose) but don't hold your breath waiting for them to work.
Remember however that repellents are only short term fixes. They all have to be reapplied after rainstorms, and the instructions should be carefully followed.
For persistent problems, especially with digging dogs, a sturdy fence is the most permanent solution. I wonder if the dogs are coming in nschmidt's garden to hunt the rabbits? An excellent new book on animal problems is The Backyard Battle Plan by Cooper Rutledge, published by Penguin.
Question: While recently renovating a 1970's colonial, we found a wall infested with ladybugs. They are all over the house and the attic is swarming with them. People say they are good luck. I like them and am not bothered, but am curious as to what attracts ladybugs.
Answer: They often come indoors for protection in the winter and will swarm or congregate in one corner or inside a wall. They do no harm, and are the best of bugs for they eat bad bugs in the garden. On a nice day, open a window and let them out. I congratulate you for your good sense. Some folks get hysterical and try to kill them with pesticides. I actually have a ladybug house in my garden, but no lady bugs moved in for the winter, despite my using an insect pheromone attractant called Eau d'Ladybug, which smells a little like alcohol .
Question: I would like my children to be able to play outside but am afraid of Lyme disease ticks. I am also concerned for my husband who plays golf.
Answer: Lyme disease, which began on Long Island, then traveled to Lyme, Connecticut, is now widespread in the east, as well as other parts of the country.
If left untreated, it can become a serious, debilitating, chronic disease, but can be stopped with antibiotics if diagnosed early. It is carried by the deer tick whose carriers are deer and the white footed mouse. The ticks need red blood to grow and reproduce and when biting spread the disease.
The best protection is to use a repellent containing DEET. It has just been reapproved by the EPA for TICKS AND MOSQUITOES for adults and children, but not for babies. It is absorbed through the skin. (Read the directions on the labels carefully. Don't use constantly.)
They recommend 15-30% DEET for adults. Stronger solutions do not repel more, they only last longer. DEET may also be sprayed on clothes. There are special formulations for children that limit absorption. One for children, called SkeDaddle, has a lotion base, rather than alcohol. Thick shoes, pants are also recommended, with thick socks tucked inside the pants.
Most important, always check yourself and your children when you come inside for the tiny poppy seed size black ticks. Remove them carefully, being sure to get the whole head, which if left can still cause infection. (Putting on alcohol first may make them loosen their grip.) The good news is that the tick has to be attached for 24 hours to transmit disease.
The most dangerous places are in long grass, shrubs, weeds and brush, in fields, woods, golf courses and also next to the lawn. Lawns can also be infested, sometimes heavily, however the risk of walking in the brush for one minute is equal to about 90 minutes on a lawn.
The number of ticks on a lawn can be reduced by 70 to 90 % by using the standard lawn grub-proofing insecticide, and applying it early May, and then again in June. The insecticide that was tested for these figures was carbaryl (Sevin). Malathion has also been recommended though it doesn't last as long. However these two are not safe for lawns where children play or pets run. Merit, a safer insecticide is currently being tested. Or use a repellent with DEET.
The ticks are most abundant and most infectious May, June, and July. Then they go dormant for a few weeks before emerging as adults, and look again for another blood meal. A new vaccine has just been introduced which is worth investigating in endemic areas.
Mowing Grass to make a Pattern
Question: How can I mow my lawn to get the CROSS HATCH DESIGN that the major league ball parks have on the outfield?
Answer: Experiment with mowing in two directions, First go one way, then go over it another, leaving spaces between each mow.
Question: My peonies are very healthy but have very few blooms? What can I do?
Answer: The two most common causes for poor flowering are too deep planting, or botrytis blight, a fungus that makes the buds shrivel up and turn brown. The eyes of a peony tuber should be no more than one inch below the surface. Check them in early fall or spring. Then either replant and raise them, or scrape away some of the surface soil, making sure that you leave positive drainage, not a soggy wet hole. For botrytis blight, in spring, spray the shoots with a fungicide, when they are 8 inches tall, and repeat at 7 to 14 day intervals until the flowers open. Bordeaux powder is the old fashioned remedy. Modern fungicides are mancozeb, chlorothalonil, benlate or thiophanate. Sometimes ants eat the sugar produced by aphids on the buds. They milk the aphids like cows. While the ants don't affect blooming, they may spread the fungus. Aphids can be controlled with a very weak soap solution or pyrethrum. It has to be applied fairly frequently, since aphids reproduce rapidly. Spraying can damage the tender bud as it unfolds, so timing is critical. You really can't win when you fight the insect world! Peonies are among the most reliable and satisfying of the old perennials. They take 2 to 5 years to mature, but when happy, last a lifetime. The flowers are glorious for a week or two, and the foliage is lovely all summer, and makes an excellent green summer border. Unfortunately they are subject to many ills, namely antracnose and fusarium wilts (treat these with a fungicide). Also thrips, Japanese beetles, rose chafer beetle and rose curculio (spray leaves with carbaryl, resmethrin or malathion). And viruses too (nothing helps). Peonies do best in open, full sun. The problems with fungus and insects are often the result of too little sun, too much moisture on the leaves, or too little air movement. Peonies appreciate a complete fertilizer in spring, with adequate phosphorous to feed the tubers underground.
Pruning Climbing Roses
Question: When is the best time to prune climbing roses?
Answer: Roses are pruned in the spring, before growth begins, but it is far more complicated than pruning snowball bushes. The primary purpose in pruning roses is to remove dead wood and shape the bush. Each type of rose (i.e. hybrid teas, bush roses, climbing roses, old fashioned roses) have different nuances and needs when pruning. Climbing roses require some special understanding. Most of them bloom on second year wood which means the flower buds are formed the previous summer. A few even bloom the third year. Some old fashioned varieties bloom only once a year in June. Ever blooming climbers generally have two main flushes of bloom, in June and September. The main thick branches (or trunks) growing from the base, should be retained as long as they remain alive and productive. The side branches are pruned back as needed to remove old, dead wood and to train the bush. Always save the new green shoots that arise from the base in midsummer. These are the ones that will provide the best blooming for the next several years. (Caution though, check the leaves. If they look very different from the ones on flowering branches, they may be undesirable root shoots which should be removed immediately. Root stock shoots usually have many, small leaves and more thorns, like the wild roses or brambles.) Climbers and bush roses produce more flower buds on branches that bend sideways even to horizontal. Upright vertical branches usually produce flowers mostly at the top . To induce better flowering, either encourage side branches off the main trunk (like vineyard grapes ) or train the main branches when they are young and pliable into a fan shape. If cane borers (small black flies, that lay their eggs in spring in the soft pith of newly cut stems) are a problem, seal the cut ends with a thumb tack or a drop of Elmer's Glue. One of my books, Landscaping that Saves Energy and Dollars ( Globe Pequot Press ) has a section on pruning roses, as well as pruning other plants in the chapter called "How to Use Existing Plants".
Pruning Tree Branches
Question: When I am pruning a branch from a tree, should I cut it flush with the trunk, or leave a stub? Should I use black tree paint?
Answer: Research has shown that trees heal better when a small stub is left in place. This stub, which is called a "branch bark collar", sticks out 1/2 to l inch at the top, and is cut at about a 45 degree angle to the trunk with the wider part (perhaps 1-2 inches) at the bottom of the stub rain water can run off. The tree "walls off" the pruning cut with protective substances in the cells of the branch bark collar. It's sort of like a scar that retards infection with fungi that cause rot. A flush cut often leads to decay after some years. Tree paint is unnecessary and does not protect the cut, although there is ongoing research for a substance that will retard fungi.
Question: My hydrangea looks dead. It doesn't have any leaves. Should I cut it back to the ground each spring and hope it will grow back?
Answer: No. Hydrangeas leaf out late, so leave the old dried up stems from last year and wait a bit. The flower buds are carried in those stems, so never prune them lower than 2 feet. As it warms up, the buds will swell and sprout. Stems that have no live buds can be cut off at ground level. On healthy plants, new shoots will come up from the roots. Prune August flowering white hydrangea in early spring. Prune blue hydrangeas just after they finish blooming. When dried, the flowers will keep the color they have when they are cut. Blue, Pink or Green.
Question: My lilacs are very overgrown and I don't know how to prune them.
Answer: Lilacs can be renewed by letting a few new sprouting canes grow up from the ground each year. The rest are removed if there are very many. Since Lilacs bloom on shoots that are 3 years old, these shoots perform well for several years. After a while, they get thick and tree like. These oldest thick trunks are removed, usually one a year, especially as they get very woody and particularly if they have borers. (Borer emergence holes can be seen in the bottom 2 feet on the trunk. Also the trunk may have dead wood.) French hybrid lilacs grow to about 8 feet tall, while old fashioned ones grow to about 20 feet. Korean lilacs are smaller. All lilacs need sun to bloom well, some spring fertilizer and occasionally some lime.
Pruning Snowball Bushes
Question: When is the best time to prune snowball bushes?
Answer: The name snowball bush is applied to several plants, the Japanese Snowball and Chinese Snowball and the European Snowball, which are all viburnum varieties. Japanese and Chinese Snowballs bloom in spring and their flowers often remain for up to three weeks. European Snowball, an old fashioned variety, is subject to attacks of disfiguring plant lice so is not as desirable. In general, spring flowering plants bloom from buds formed the previous season. Any serious pruning is done just after flowering, so the plant can set buds for the following year. Sometimes a little light trimming can be done during the dormant season. Most viburnums don't need much pruning. When they get overgrown and need thinning, the oldest trunks can be cut off at the ground , and the younger, more vigorous shoots left to grow on. Most are big shrubs. When they get too large, they sometimes need to be cut back, although this may destroy the graceful shape of the shrub. Occasionally , when shrubs get too tangled and overgrown, they can be renewed by being completely cut back to the ground in spring ( after enjoying the flowers) and fertilizer is spread around them on the ground. Sometimes they take two or three years to bloom well again. The English often renew their shrubs in this manner.
Rhododendrons - Winter Kill
Question: What should I do with the dead branches and brown winter killed leaves on my rhododendrons?
Answer: Wait until the end of June before you prune out the dead branches. Injured plants bud and leaf out very late, so you can't tell yet what is really dead and what is alive. New shoots will appear, even from thick old broken branches. Sometimes it takes 2 years for the old wood to sprout. If you can't stand the discolored leaves, cut off the brown edges with a scissors, until the flowers appear and new growth starts.
Question: Why do I have dead branches on my roses that are hollow inside when I cut them?
Answer: The rose cane borer lays its eggs in the soft, juicy center of fresh pruning cuts in early spring. The adult is a small black fly that's attracted to the smell of the fresh cut. The larvae bores down and eats out the center of the cane, causing it to die, usually over the winter. To prevent this, seal fresh pruning cuts with a few drops of Elmers glue or thumb tacks. The borer can't lay eggs through these. Candle wax will work too, but it's the devil to try to drip wax into thorny roses.
Question: I have heard that there is a "Rose Fever". What kind of a disease is it?
Answer: Actually Rose Fever is a misnomer. One doesn't get a fever from roses, but some people can get an allergic reaction from rose thorns. Brambles, raspberries and old fashioned wild roses, have thorns that cause a local reaction when they get imbedded in the skin, and are not removed. The tiny ends have a habit of breaking off when you get stuck. You can't always see them, but you can feel them because of the irritation they cause. They are best removed with a magnifying glass and tweezers. Also, when the roses are in flower, so are many other plants, particularly grasses, so lots of people have allergies and hay fever during the rose season in June.
Seaweed - Yes it's Good
Question: I have heard that seaweed is very good for plants. Can I use old seaweed from the beach in my garden?
Answer: Yes, if you wash all the salt out of it. If it is high up on the shore, the rain has washed out most of the salt, but give it a good hosing down anyway. Seaweed is a good fertilizer, and probably has some substances that act as plant hormones as well. Because it has many minerals, when it's dry it can be too concentrated, so mix it with the soil. Don't worry about the flies. They will die. There are several root and growth products that incorporate seaweed (kelp) in their formulas.
Question: Where can I get a manual sod cutter, the kind with two handles and a kick plate?
Answer: Many machinery rental stores have them. These are heavy pieces of equipment, weighing about 250 pounds with a sharp blade, so for safety, wear steel toed boots. The trick is to cut the sod thick enough, but not too thick. About 3/4 inch of soil is about right. In shady areas, where the grass is thin or has poor roots, it's not worth using a sod cutter. Also sod can be cut easily with a square edged spade, and then picked up in chunks or small rolls. If sod is immediately replanted into well prepared soil and watered, it will generally take root. Like a divot on a golf course.
When To Start Planting
Question: How can you tell when the soil is ready to plant?
Answer: Squeeze a ball of earth in your hand. If it makes a mud ball, it's too wet. If it crumbles, you can dig and plant.
Eastern Tent Caterpillar
Question: What can I do about the big webs with caterpillars in the forks of my crabapple trees?
Answer: The Eastern Tent Caterpillar is active in May eating the leaves of apples, peach, wild cherry, lilac, cotoneaster and many others. They come out of their web nest to eat on warm days. You can remove the nest with a very strong stream of water, or by hand rolling it in newspaper on a stick. Don't burn it in the tree! Or, you can spray the leaves and inside the nest with Bacillus Thuringiensis (BT) when they're young and small. Or spray with Rotenone + Pyrethrum, Sevin, Diazinon, Malathion or Chlorpyrifos. If you do it at night, you'll hit more of them.
Transplanting - Must I use Peat Moss
Question: I've been told to add l/3 peat moss to my soil when I plant new shrubs. Do I have to?
Answer: The current wisdom is not to. Tests at the Morton Arboretum in Illinois showed that plants do just as well using ordinary soil as backfill, but it should be well dug and loose, in a wide hole. Compost is helpful and fertilizer too both mixed well with the soil. Watering with one of the new transplanting aids that contain beneficial soil microbes and humus (often from seaweed kelp) help the plant put out new roots. If they are not available, a 1/2 strength solution of soluble liquid fertilizer will help with rooting. Most important is to water well once a week for the first year.
Tree Planting Depth
Question: I think my trees were planted too deeply. How can I tell?
Answer: In a properly planted tree, the root flare, which is where the trunk widens, should be visible above the ground. If the trunk is straight all the way down into the ground, the tree has probably been planted too deeply.
Question: I'm looking for a Victorian trellis with an oriental look to it to go with my Victorian house?
Answer: Decorative shade arbors or trellises were common at the turn of the last century; some were very complicated, especially those with an oriental motif. You might call 1-800-343-6948 for the Walpole Woodworkers catalogue, (cost $10) which has a number of arbors and gazebos most compatible with Victorian architecture, though not line for line reproductions.
Question: Is there a company that manufacturers large wire baskets called "mossbaskets"?
Answer: These are usually used for hanging planters. The wire is lined with moss mats and flowers planted in the top and around the edges, right into the moss. Most large nurseries carry these or can get them. If you can not find a source, they are manufactured by a wholesale supplier, OFE International, Inc., P.O.Box l6l302, Miami, Fla. 33116 in sizes from 8 to 30 inches. They might be able to provide a retail outlet in your area if you write to them.
Woodchips and Trees
Question: In very well maintained properties, I see that wood chips are mounded around the trees like volcanoes? Should I do this to protect my trees?
Answer: It is a very bad practice that has become popular and I don't know how it started. Mounded up wood chips cause fungus and rot, and also interfere with the transport of sap up and down the tree.
Wood chips should be kept about 2 inches away from the trunk, and should not touch the tree. Farther out, over the roots, their total depth should be 2-3 inches, no deeper. A ring of wood chips keeps the roots moist and prevents damage from lawn mowers and weed wackers.
Year Round Blooming Garden
Question: I have the farthest thing from a green thumb and want to know the best places to place plants. My goal is to have a year round blooming garden. I'd love to find someone like Ruth Foster - Landscape Architect, my idol, to help.
Answer: Your letter was so uplifting that I have framed it and put it on my wall. In answer to your question of how to plan such a garden, I have written a special column just for you called "Sequence of Bloom." Good luck! If you really want to have flowers all summer, also add some annuals, plus a few impatiens in the shady bare spots. Then use Peter's 20-20-20 liquid fertilizer ,or something similar, to keep them blooming. Actually I wrote a book called Landscaping That Saves Energy and Dollars, the whole second section of which is about how to design your own property and suggestions for year round color. Also check the Burpee's free catalogue for some suggestions for flower collections that bloom over a long period.