Tending a garden in December

By Don Davis
Published: December 2, 2008

There is still some gardening to do at the end of the year. Plants outdoors and indoors will benefit from some attention in December.

Seed and plant catalogs for next year have begun to arrive. Now is the time to open them up, and look for new and interesting items. It is not too early to think about your 2009 garden and what you will be planting.

For fresh vegetables, you could plant onion and garlic this month. The onions to plant are onion sets, which are tiny bulbs less than an inch wide. They will provide green onions for your meals in March and April, before they go to seed in May. To grow onion bulbs like you see in the grocery store, you plant sets, seeds or seedlings in March.

To grow garlic, you separate garlic bulbs into individual cloves and plant them 5 inches apart. Each clove produces a new bulb that is ready to harvest at the end of June. Fall-planted garlic grows bigger than spring-planted garlic.

The weather trend has been a dry one, so be sure to check on anything you planted this fall and make sure it has adequate moisture. One more watering may be needed by new shrubbery, trees and flowers before winter sets in. Give water to potted plants first, and make sure everything is mulched to conserve water.

Lawns still show extensive dead spots caused by the summer drought, and there is a long time to wait before warm temperatures will stimulate growth of any new blades of grass. A dose of nitrogen fertilizer before Dec. 15 could be good for root growth, but only if your lawn is still green. Grass turning yellowish due to cold conditions does not need fertilizer.

Your houseplants could need watering more often in winter than in summer, as relative humidity is lower due to home heating systems. Their leaves curl, wilt or turn yellow when the soil is too dry.
Other ways to tell if houseplants need water include feeling the soil at a 1 inch depth with your finger and picking up the plant. Houseplant soil is primarily sphagnum peat moss, a brown material that is heavy when wet and light when dry.

Hardy shrubs may be pruned now. This includes summer bloomers such as glossy abelia, butterfly bush and Japanese spirea. It also includes shrubbery grown mainly for colorful foliage such as juniper, burning bush and Japanese barberry.

Some trimming is necessary if you want greenery for holiday decoration. Among the better plants to cut a few twigs from are nandina, boxwood, holly and southern magnolia. The native American holly trees are particularly full of berries this year.

English boxwoods growing in partial to full sun require thinning on an annual basis. This involves clipping out small branches and creating holes in the canopy where air and light can penetrate.