April 8, 2013

Tips for extending the growing season

By AMY IVY, Cornell Cooperative Extension

---- — North Country gardeners are always looking for ways to add a few more weeks to the growing season. 

While you should be able to get a decent crop of most vegetables without having to provide extra protection, a little bit of effort can result in a much larger yield with a longer period of harvest. 

It’s important to understand the needs of each crop you plan to grow. Cool-season crops are those that can take a light frost and grow well under cooler conditions. They include spinach, lettuce, parsley, onions, leeks and peas. Warm-season crops will be killed if frosted and need temperatures above 70 degrees to thrive. This group includes tomatoes, peppers, beans, squash, melons, cucumbers and basil.

Although warm-season crops may not die during cool weather, they won’t put on much growth until they have those warmer temperatures. The cool-season crops are the easiest to work with in our climate as you try to extend your season.

Traditionally, gardeners make their plans around the local date of the last chance of frost. If you want to gamble and set out frost-sensitive plants before that date, you need to have frost protection at hand to help them survive when cold weather is predicted. But that date is getting harder and harder to predict as our weather seesaws from warm spells to cold snaps. I used to say that May 20 was a safe guess for the latest chance of frost in the Champlain Valley, and early June in the higher elevations of Dannemora and Lake Placid. You might try pushing that back a week or two now, but be ready for anything.

Rowcover is the generic term for a lightweight fabric that can be either laid right over the crops or held up on hoops above the foliage. The fabric resembles dryer sheets and is porous enough to let rain, sunlight and air circulate. It comes in many widths and lengths, although you may have to use mail order to find the larger sizes. 

I like rowcover because it’s so porous that heat and humidity don’t build up underneath. But because it’s porous and lightweight, it offers little, if any, frost protection. Think of rowcover as a way to warm up the daytime growing conditions a bit and especially as a way to protect your crops from wind. Young, tender leaves have a tough time in windy conditions. Simply blocking the wind can really help young plants thrive.

Most crops do best when the cover is supported on low hoops. You can use flexible PVC pipe or sturdy wire to form hoops about 2 feet high over your crop rows. If you use raised beds that are framed in wood, you can drill holes right into the wood to anchor the wire, or sink the ends of the wire or pipe along the inside edge of the frame to provide some support. Set the hoops 2 feet to 3 feet apart then lay the rowcover over the top, leaving plenty of extra along the sides and ends for anchoring down.

If your garden is in a windy location, fasten twine or heavy string over the rowcover, between the hoops to help hold down the fabric. The wooden sides of raised beds are ideal for adding hooks to fasten down these anchoring ropes.

To learn more practical gardening tips, don’t miss our biannual Spring Garden Day on Saturday, April 20, at Clinton Community College. Registration is due soon, and classes are filling up. Contact our office for more information.

Amy Ivy is executive director of Cornell Cooperative Extension, Clinton County. Office phone numbers: Clinton County, 561-7450; Essex County, 962-4810; Franklin County, 483-7403. Website: Email questions to