As of Wednesday, February 25, 2015
A milder-than-usual winter has vegetable gardeners itching to get their hands in the soil. But that’s not a great idea.
“One of the biggest mistakes people make is to plant too early,” said Weston Miller, a horticulturist with Oregon State University’s Extension Service. “They get excited when it’s sunny for a few days, put plants in the ground and think they will grow. But the seeds either rot from damping off fungus or germinate very slowly. At the very least, they’ll be stressed for the rest of the season and never catch up.”
Wait at least until the end of February or first part of March in the North Willamette Valley, he advised, and then only plant cool-season vegetables like peas, arugula, mustard, radishes and turnips.
In April, he said, expand the palette to include carrots, beets, scallions, chives, parsley and cutting greens that are easy to grow from seed; or plant already-started transplants of kale, head lettuce, chard, leeks and onions.
An inexpensive soil thermometer helps keep planting time in perspective.
“Soil temperatures right now are in the 40s,” Miller said. “That’s too cold. Fifty degrees is a good benchmark for cool-season crops. And the soil should be 60 degrees or more for warm-weather plants like tomatoes, peppers and basil. In fact, for tomatoes it should ideally be 65 to 70.”
If you can’t resist the urge to plant, Miller recommended using some sort of protection from the chill like a floating row cover, individual glass or plastic cloches, or even milk jugs or soda bottles with the top cut out and turned upside down over plants. For directions on building a large, greenhouse-type cloche with PVC pipe and plastic, check out the OSU Extension guide on How to Build Your Own Raised Bed Cloche.
Whether the warm winter will mean soil warms earlier this year is a matter of conjecture, Miller said. There still could be a cold snap in the next month.
“Gardening depends on the weather, which is unpredictable,” he said. “But it pays to wait.”
You’ll find more information about vegetable gardening, including schedules for planting, in the comprehensive Extension publication called Growing Your Own.
Five Tips for a Successful Garden
• Prepare the soil. For existing garden beds: Add 5 to 10 pounds per 100 square feet of lime in the fall. Before planting, add a moderate amount of compost (¼ to 1 inch) and a balanced fertilizer (all three numbers on the bag are the same) according to package directions. Incorporate the materials into the top 8 to 12 inches with a digging fork or spade. Rake bed before planting seeds or transplants. For new garden beds: Remove sod or weeds to expose soil. Liberally add 4 to 6 inches of compost, agricultural lime and a balanced fertilizer and incorporate into the top 8 to 12 inches with a digging fork or spade. Prepare seed or transplant bed with rake.
• In addition to adding complete fertilizer to the soil, use a soluble fertilizer like fish emulsion for transplants, especially early in the season or if the plants are not thriving.
• Use transplants when possible. Crops that do best when seeded directly into the garden include carrots, parsnips, beets, radish, turnips, mustard and arugula. Most other crops can and should be transplanted to make the gardening process easier, particularly for weed control. Grow your own transplants or look for high-quality starts (not root bound, stunted, off-color) at the garden center for best results.
• Control weeds early in the growth cycle of your veggies.
• Monitor and control slugs and other insect pests often. Keep an eye out for slugs. Find them under debris and in the folds of plants and dispatch them by dropping into soapy water or cutting them in half with scissors. Look for aphids, imported cabbage butterfly larvae, and other pesky critters on the underside of the leaves. Squash them.
-Weston Miller, horticulturist, OSU Extension Service