What to do in the garden before the first frost arrives

Jeana Myers is thinking about getting her garden in Raleigh, N.C., ready for the first frost, even though it's still likely weeks away.

Work in the garden doesn't end just because those long days of summer are over.

Ms. Myers' peach, plum, and other fruit trees have stopped bearing fruit, and the tomatoes are ripening more slowly as the days get shorter and the temperatures cooler.

By mid-October, she'll begin to pull the green tomatoes off the vines, to eat or to let ripen. "If a freeze hits them, they're done," says Myers, a soil scientist for the North Carolina Department of Agriculture.

As the season ends for tomatoes, squash, and other summer vegetables, it's prime time for leafy green vegetables like spinach and arugula. "We can really grow vegetables year-round," Myers says. "Our challenge is that it's going to get really hot again." The green leafy vegetables don't like those warmer temperatures.

Historically, the first frost arrives in her area around Oct. 15. Some northern parts of the country already have been hit with frost advisories.

Most places still have a month or so of growing season left, says Charlie Nardozzi, senior horticulturist for the National Gardening Association.

Many gardeners will cover their plants to try to protect them from the cold and extend the growing season. Floating row covers, made of a cheesecloth-type material, let in light, air and water. "They protect the plant like a blanket," Mr. Nardozzi said.

Some people lay the row cover directly over the plants. Others build a frame. You also can use metal hoops and create a tunnel for the plants, Nardozzi says.

The covers provide a few extra degrees of protection when the temperature drops below freezing.

Myers puts bales of hay around special plants. "They have a lot of insulating value," she says. She'll also use a kelp spray, which she said improves the plant's resistance to cell damage under cold conditions.

Some plants do better than others as the weather turns cold.

"All the rooting vegetables like turnips and beets, they'll be fine," says Christopher Gunter, a vegetable production specialist and assistant professor at North Carolina State University. He said the soil has a "buffering heat" that will keep these vegetables warm even during a mild frost.

Besides trying to coax a few more ripe tomatoes out of your plants, fall is also a good time for garden cleanup.

"A lot of people are sort of tired of their garden," says Susan Barton, an extension specialist at the University of Delaware. "Once it stops producing they just want to forget about it. While you can do that, you allow all of those fungal spores to overwinter, and insects, too."

That can mean trouble for your garden come spring.

Annual plants should be pulled and composted — provided they are disease free.

Once the plants are out, compost or manure can be spread on the beds and worked into the soil. Any kind of organic matter will do, Nardozzi said.

"Use your leaves wisely," Ms. Barton says. "Leaves are a wonderful compost."

Preparing garden beds now gives the organic material time until spring to decompose and fertilize the soil. But do it before it gets too cold, Gunter says, to give the micro-organisms a chance to start breaking down the material.

To prevent erosion during the winter, Nardozzi recommends planting winter rye or winter wheat seed.

At the community gardens in Portland, Ore., growers are encouraged to clean up their plots and then plant a cover crop like alfalfa or legumes, says botanical specialist Dan Franek. "It shows us their plot is still active." Legumes also are an excellent source of nitrogen for the soil.

Fall also is a good time to aerate and fertilize the lawn.

New trees and shrubs can be planted — there's still time for the roots to get established before the soil gets too cold. Nardozzi recommends putting a tree wrap or guard around young trees so mice or voles don't do damage during the winter.

And tropical plants can be dug up and brought inside. First, though, prune them back, pull off any dead leaves and check for insects, Barton says. "Sometimes it's a matter of washing off the plant with a hard stream of water."

But what about those unripe vegetables and herbs?

Some herbs, like rosemary, are perennials and come back in the spring. Annuals, like basil, won't survive the first frost. Basil leaves can be pulled and dried. Or, you can make pesto and freeze it to last through the winter.

Tomatoes that are beginning to show color — even a spot of pink — likely will ripen in time if pulled and brought inside. Put them on a window sill in a warm, well-ventilated area, Gunter suggests.

Individual tomatoes that are starting to ripen also can be wrapped in a piece of newspaper and stored in a basement for a couple of weeks, Barton says. Make sure they're not touching one another, or they may rot.

And for those tomatoes that are entirely green?

There's always fried green tomatoes, a classic Southern dish.

Editor’s note: If you’d like to read more about this topic, check out this Monitor blog post by Judy Lowe, which includes tips on detecting the first frost and how to overwinter plants.

For more on gardening, see the Monitor’s main gardening page, which offers articles on many gardening topics. Also, check out our blog archive and our RSS feed. You may want to visit Gardening With the Monitor on Flickr. Take part in the discussions and get answers to your gardening questions. If you join the group (it’s free), you can upload your garden photos and enter our next contest. We’ll be looking for photographs of fruits. So find your best shots of summer’s blueberries, peaches, plums, etc., and get out your camera to take some stunning shots of early fall apples. Post them before Sept. 30, 2009, and you could be the next winner.