Deer candy

Are there any plants that deer won’t eat? What can we grow on our wooded lot, where there are plenty of deer? Joanne, no address

The best way to keep deer from eating plants is to erect a fence. Our research revealed mostly conflicting reports of what deer will and won’t eat, with one Cornell professor stating that plants deer ordinarily avoid become deer candy when the deer are hungry enough. Sumac, boxwood, cotoneaster and barberry were mentioned often as deer proof, as were foxglove and goats beard. If you have planted something young and vulnerable, I would spray it with Ropel, an extremely bitter substance that has reduced browsing damage in many gardens. Heavy-Duty Deer Fence

Pollen-free trees

I have recently cut down a declining honey locust tree in my front yard and I really don’t want to replace it because I am allergic to tree pollen. Is there such a thing as a pollen-free tree? T. A., Kankakee

Actually there is. There are two types of flowering trees, those with male and female flowers on separate trees and those with both male and female flowers on the same tree. Many are pollinated by wind—oaks for example—others, like crab apple, by insects. It is the windborne pollen from the male flowers that is the source of your discomfort.

Unfortunately, since homeowners don’t want to deal with the messy fruits of a female tree, (like ginkgo or honey locust) we have cloned and sold only males of many species, significantly increasing pollen in the air.

The good news is that there are several easily available and adaptable trees that are pollen-free. The beautiful and tough Washington Hawthorne has glossy leaves, red fruits and good fall color. Magnolias with rose colored flowers, like ‘Betty’ and ‘Vulcan,’ or the newer yellow-flowered types like ‘Elizabeth’ and ‘Butterflies,’ produce little or no windborne pollen. Among maples, you can breathe with ‘Red Sunset,’ a hybrid that is very adaptable and has good fall color.

Goats beard

I have three goats beard (Aruncus dioecus) plants that were all purchased and planted at the same time, in the same bed. Two of them have remained spindly and seem to crisp or burn up on the edges and the third one is huge and lush. What could make this happen? D. F. S., by email

There can be many factors involved in the failure of individual plants to thrive. Because individual plants are genetically variable, it is possible for one plant to simply be stronger and more robust than another. It is also possible for one plant to be different from others because it is a different cultivar that has been mislabeled or misidentified. Occasionally, a plant will produce seedlings that are stronger and out compete the original plantings, producing a very different plant. This happens with mums and phlox frequently.

More likely with your goats beard, it is a case of imperfect soil pockets or microclimates. Goats beard are related to astilbe and like similar conditions; moist, rich soil and afternoon shade. Appearing like a giant white-flowered astilbe, but less temperamental, they make a strongly-architectural statement in the border. They should reach 4 to 5 feet after two or three years and stay beautiful for many years without dividing. The two that are spindly and poor may be getting too much sun, they may be getting shaded out by the larger plant, or they may be deprived of water by a pocket of poor soil. Try lifting all of them out this fall and working some compost into the site before replanting. If the smaller plants do not respond, replace them.

Poor foundation

I have a strip along the foundation of my house, on the east side, where absolutely nothing will grow. I have tried yews, hosta, azaleas and hydrangeas. Is it because the area is too alkaline? C.S., Beecher

Probably not; alkaline soil shouldn’t affect yews or hosta. It is probably too dry there. Go out after a rain and dig around a bit and you will probably find that water is not reaching the site. You may be able to remedy the problem by replacing your single valve spigot with a double (or triple) valve, brass head and running a length of soaker hose along the center of the bed. The multiple port spigot allows you to keep the soaker hose in place and still use your regular hose. Then simply open the shut-off lever on the soaker hose once a week or so and let it run until the bed is irrigated. By using a slow-drip soaker hose, you will not be introducing the water fast enough to cause basement flooding. The black hose can be hidden by a light covering of mulch.

Drought damage

My pagoda dogwood leafed out sparsely in the spring with empty branches here and there. A lilac at the other end of the yard did the same thing. Any idea what the problem is? M.S. Momence

Sparsely leafed out trees and shrubs, some showing severe dieback, were fairly universal last spring. Dieback can be caused by a number of problems. Rule out nutrient deficiencies first by examining leaves for yellowing between veins and scorched edges. Decline in several plants of different species affected at once may indicate an environmental problem like herbicide drift. Look for small or twisted leaves with red margins. A girdling root or being planted too deeply can cause problems years after a tree is planted.

Most likely, because we had another period of extended drought late last year, it is simply a case of too little water getting out to the branch tips and leaf buds. Pagoda dogwoods are listed by the Extension Service as being especially vulnerable to these conditions. Water trees deeply during extended periods without rain, especially in the fall.

Prune out the dead branches of your pagoda and assess the tree to see if it is salvageable. (I have lost the entire top of a Japanese maple to dieback and it still grew to be lovely and full again.) Your lilac can be cut back hard or pruned to thin out dead branches.

Mushroom compost

I have heard that we shouldn’t use mushroom compost anymore because it is too salty. Is this true? I like to use it instead of mulch. N.S., Manhattan

Mushroom compost is a very good soil amendment, but it should not be used every year. There does seem to be some evidence that it contains levels of salt that could be injurious to roots and damaging to soil health if over used. Many landscapers use it heavily to amend poor soil and botanical parks use it to dress beds, avoiding that ‘mulched’ look. We think using it cosmetically or as an amendment when planting is safe. The best way to avoid using any mulch is to cover the ground with plant material, reducing open soil.