The Sweet Results of Fall Vegetable Gardening

WRITER | JULIE FORD

As the weather turns cooler, it’s time to wrap up another successful season of vegetable gardening, or is it? Traditionally, this involves harvesting and preserving the remainder of the vegetables by early September and preparing the space for a long winter’s nap. In addition to the typical harvest activities, why not try saving the seeds from this year’s bounty or extending the growing season into winter?

When favorite flowers go to seed or while crafting a homegrown jack-o’-lantern, you can collect the seeds and dry them on newspaper. After the seeds are completely dry (very important to avoid spoilage), store them in airtight glass jars and place them in the refrigerator for maximum temperature consistency. Depending on the seed type, stored seeds can last for years, but the goal here is storing them to plant in next year’s garden.

While fall’s cooler weather can damage some vegetables, others actually thrive. Frost damage occurs when the water in plant cells freezes, expands, and bursts the cell walls of cold-sensitive plants such as beans, melons, tomatoes, and peppers – requiring final harvesting in late summer. Vegetables such as peas and radicchio can handle a light frost, while broccoli, broccoli rabe, beets, carrots, leeks, lettuce, kale, and Swiss chard can withstand a hard frost. The backs of seed packets generally indicate the frost-tolerance of vegetable varieties.

To truly capitalize on extending the growing season with frost-tolerant varieties, count backward from the desired harvest date to know when to direct-sow, and add two weeks since the cooler weather can slow growth. For example, the Bolero variety of carrot from Johnny’s Seeds matures in 75 days, plus the additional two weeks equals 89 days. If the goal is to harvest November 22, the seeds should be sown by August 22.  Carrots and beets are excellent choices to harvest late due to their tendency to get sweeter as the nights get cooler. Since sugar water freezes at a lower temperature than water, the sugary cells of carrots and beets prevent the cell walls from bursting, and the slower growth facilitates the sweetening process.

For Linda Whitlock, Michigan State University Extension horticulture educator, Thanksgiving dinner always includes carrots freshly picked from her garden using a cold weather gardening tip from her father. “I mound up a ‘cold storage’ of 10- to 12-inches of leaves over the carrots and leave a little bit of the green showing,” explains Whitlock, adding that she harvests as late as January. Straw, wood mulch, or pine needles can be used instead of leaves to warm the soil and create a microclimate that extends the growing season.

For late fall and winter gardening, consider installing a cold frame – a bottomless box made with either untreated wood sides and a clear glass top, or an all-glass box (which requires southern exposure and a windbreak that does not shade the box). Cold frames create a microclimate that absorbs the sun’s energy and germinates seeds in temperatures as low as 50 degrees. Frost-tolerant vegetables can be grown in a cold frame in late fall and continue through winter with careful monitoring to be sure moisture is even, and that sunny spells don’t burn the plants.

To prepare the garden soil in fall for the following spring, Whitlock suggests leaving legumes in place, as they return nitrogen into the soil. Tomato and pepper plants should be removed due to their susceptibility to fungal issues and the likelihood of the spores overwintering. For this reason, any wooden stakes should be left outside over the winter to reduce spores. Whitlock suggests stripping all garden vegetation to bare soil if there were serious disease or insect issues; otherwise, covering the soil with leaves or planting a cover crop for “green manure” is best.

With a little know-how, fall gardening practices help to improve next year’s yield while extending the joys of gardening, especially when Thanksgiving dinner includes a serving of freshly picked homegrown vegetables. Just cook and serve – nature already added the sweetness.