Garden Q&A

Question:

We recently removed part of a deck near Cape May and wish to put in a variety of shrubs and plants. The soil is yellow-orange, probably a mixture of sand and clay. Even in a large planting hole, won't the roots eventually encounter the surrounding fill, which has little or no nutritive value? Removing considerable quantities and replacing it with good soil seems impractical.

- Walter Slomski

Answer:

Dealing with the earth adjoining a house is often a challenge, since it may be composed largely of subsoil from cellar excavation or may be laced with construction refuse, the most worrisome of which is cement and concrete debris.

Do not assume, however, that there is no nutritive value. There may be excellent micronutrients, but the drainage and composition of the matter are otherwise not so good. You can tell if what you have is a mixture of clay and sand very easily because that mixture, once wet and then dry, is almost like concrete.

You are right to be concerned about roots that reach the limits of a planting hole. If there is a particular imbalance - a hole full of delicious loam surrounded by inhospitable clay - the roots may well stop, make a right turn and grow along the edge of the hole, just as they do in a crowded pot. Not good. That's why the current wisdom for planting shrubs and trees is to do only minor amendment of the soil, to prevent such an imbalance - and that means choosing the right plant for the conditions you have.

First thing is to have the soil tested. (In New Jersey, look in the Blue Pages government listings for Rutgers Cooperative Extension or go to

» READ MORE: www.rce.rutgers.edu/soiltestinglab

. In Pennsylvania, look in the White Pages for Penn State Cooperative Extension or go to

» READ MORE: www.extension.psu.edu

.)

Next, conduct your own test for drainage. Dig a hole about a foot wide and deep. Try not to disturb the condition of the soil at the bottom. Fill the hole with water. If it takes longer than an hour to absorb, you have bad drainage. The situation you should particularly avoid is creating bowl effects - planting holes that hold water and drown plants.

For long-term success of certain shrubs and perennials, amendment of the soil based on the test results is really the only option. You might concentrate on shallow-rooted varieties and amend just the top 12 to 15 inches over a broad area.

On the other hand, you can see how tap-rooted plants do with negligible amendment for poor drainage. That's one of the aspects of tap-rooted plants - they send thick roots deep into the earth, piercing dense matter that would do in fibrously rooted plants. A nursery that specializes in native plants should be able to direct you to appropriate varieties. Be sure to ask about native prairie grasses with long roots for challenging situations. Tracy DiSabato-Aust's

The Well-Tended Perennial Garden

includes a list of clay-busters in the appendices.

Another option is to skip perennials and shrubs at first and experiment with annuals to see what works and what doesn't. Nasturtiums do better in lousy soil. For a more bodacious effect, there are sunflowers, tithonia and ornamental okra (

Hibiscus manihot

).