NOVEMBER
2005

 

 

 

By
Beverly Shaw
 
Advanced
Master Gardener
Purdue University

 

 

 

 

 

11-03-05

Question and Answer

Q. I have several peonies that are 80-plus years old located in an old farmstead. I would like to transplant them to a more suitable area. What would be the best way to transplant them? What do I need to do as far as fertilizer and water needs after the plants are moved. -- Rich Unger, Terre Haute , Ind.

A. Peonies are incredibly tough plants! Select a location for the transplants where they'll have good air circulation, full sunlight and some protection from strong winds. Peonies are seldom winter killed, but the flower buds are susceptible to late frosts and wind damage. Don't crowd peonies together or close to other trees or shrubs that compete for soil moisture and nutrients. Try to avoid locations where peonies have been grown before. Peonies thrive on a wide range of soils, but a clay loam is best. It must be well-drained and yet should hold moisture. Peonies need ample room for development, so plant them 3 to 4 feet apart.

October planting or dividing and resetting is preferred because plants are dormant and, therefore, less sensitive to injury. Spring planting is less desirable but can be successful if done early.

Prepare the soil at least 1 foot deep. Mix in generous amounts of organic matter, such as composted manure or sphagnum peat moss. Allow the soil to settle, or, if working the soil immediately prior to planting, pack the soil firmly to prevent settling once the roots are planted.

Digging, dividing and replanting will increase the number of plants. If you'd like to propagate your plants while you're transplanting them, dig up the entire clump and divide it into two or more portions. Plant each in a new location.

Dig a hole 10 to 12 inches deep in the prepared soil area. Place the plant in the hole, then work the soil in about the roots, making sure it's well firmed. The upper-most buds (eyes) should not be covered more than 2 inches. Planting too deeply is a common cause of failure to bloom. Normally, newly transplanted plants need two to three years to become established enough to produce normal flowers.

Protect your peonies with a mulch for the first winter. Mulch helps preserve moisture and prevents alternate freezing and thawing, which can heave soil and plants. Pull the mulch away from the eyes themselves in the spring.

An annual application of fertilizer will be beneficial. The best time to fertilize is immediately after the flowering season. This will enable the plants to make rapid, sturdy growth and develop strong buds for flowering the next spring. One-fourth cup of complete fertilizer per plant, such as 10-10-10 or 12-12-12, scratched into the soil surface annually is adequate.

Peonies become dormant in late September or early October. At that time, cut the stems as close to the soil level as possible without injuring the crowns, and remove all refuse. This is the surest and most economical way to prevent and control spread of insects and diseases.

Q. My wife and son planted three tomato plants under our walnut tree this summer. As they grew, then withered, I remembered that walnuts and tomatoes aren't compatible. We did get one tomato, about the size of a walnut. Are tomatoes that grow beneath a walnut tree safe to eat? Will they taste like that black yucky stuff that gets on your hands from walnuts?

Also, my wife now wants me to cut down a second small walnut tree growing amid cedars and bunch of other trees in the back of our wooded lot. She's tried to plant ferns and other shade-loving things beneath it but nothing's ever grown well beneath it. Anyway, when I noted the tomato-walnut tree problem, she immediately deduced that that's the problem with the things she's tried to grow underneath this other walnut tree. I'd rather not cut it down. Can the walnut tree toxin affect these things too? -- RGB, Avon , Ind.

A. Plants adversely affected by being grown near black walnut trees have foliar yellowing, wilting and eventually death. Tomatoes are particularly susceptible. The causal agent is a chemical called juglone, which occurs naturally in all parts of the black walnut.

The largest concentrations of are in the walnut's buds, nut hulls, and roots. However, leaves and stems do contain a smaller quantity. Juglone is only poorly soluble in water and thus does not move very far in the soil or into the plant. The flavor of your tomatoes is not likely to be affected as much as their existence!

Since small amounts of juglone are released by live roots, particularly juglone-sensitive plants may show toxicity symptoms anywhere within the area of root growth of a black walnut tree. However, greater quantities of juglone are generally present in the area immediately under the canopy of a black walnut tree, due to greater root density and the accumulation of juglone from decaying leaves and nut hulls. This distribution of juglone means that some sensitive plants may tolerate the amount of juglone present in the soil near a black walnut tree, but may not survive directly under its canopy. Alternatively, highly sensitive plants may not tolerate even the small concentration of juglone beyond the canopy spread. Because decaying roots still release juglone , toxicity can persist for some years after you remove your tree.

Species survival near or under black walnut trees is further complicated by the fact that the amount of juglone present in the soil depends on soil type, drainage and soil micro-organisms. Competition for light and moisture under the canopy also greatly affects which species survive where. I can grow columbine, often listed as juglone-sensitive, on my glacial outwash under a walnut, but I still don't appreciate being pelted with walnuts in the fall!

There are lists of juglone-sensitive and juglone-tolerant plants in the Purdue Extension publication "Black Walnut Toxicity" (HO-193-W). Ask Purdue Extension office in your county for a copy or find it on-line at http://www.hort.purdue.edu/ext/HO-193.pdf . See the links at the end of the publication for more plant lists. Following is a list of plants you might try growing under walnuts. If you see them decline, move them or lose them!

Landscape plants: arborvitae, autumn olive, red cedar, catalpa, clematis, crabapple, daphne , elm, euonymous , forsythia, hawthorn, hemlock, hickory, honeysuckle, junipers, black locust, Japanese maple, maple (most), oak, pachysandra, pawpaw, persimmon, redbud, rose of sharon , wild rose, sycamore, viburnum (most), Virginia creeper.

Flowers and herbaceous plants: astilbe , bee balm, begonia, bellflower, bergamot, bloodroot, Kentucky bluegrass, Spanish bluebell, Virginia bluebell, bugleweed, chrysanthemum (some), coral bells, cranesbill , crocus, Shasta daisy, daylily, Dutchman's breeches, ferns, wild ginger, glory-of-the-snow, grape-hyacinth, grasses (most), orange hawkweed, herb Robert, hollyhock, hosta (many), hyacinth, Siberian iris, Jack-in-the-pulpit, Jacob's ladder, Jerusalem artichoke, lamb's-ear, leopard's-bane, lungwort, mayapple , merrybells , morning glory, narcissus (some), pansy, peony (some), phlox, poison ivy, pot marigold, polyanthus primrose, snowdrop, Solomon's-seal, spiderwort, spring beauty, Siberian squill , stonecrop, sundrop , sweet Cicely, sweet woodruff, trillium, tulip, violet, Virginia waterleaf, winter aconite, zinnia.

 

Contact: B. Rosie Lerner
Editor: Olivia Maddox,