Get started with cool season crops
March 1, 2013
By Denise Ruttan
Lettuce is a cool-season crop that can be planted in March in western Oregon.
Is this dry winter making you anxious to dig in the dirt again? There's some good news if you garden in western Oregon and are an optimist.
Cool-season plants can be directly seeded into the ground in March in the Willamette Valley and southern Oregon, said Bob Reynolds, the Master Gardener coordinator for the Oregon State University Extension Service in Jackson and Josephine counties.
Cool-season crops include peas, arugula, carrots, cabbage, cilantro, fava beans, kale, kohlrabi, spinach, chard, turnips and lettuce.
Reynolds said he's getting questions from the public already about when to start planting and how to tell when soil is ready.
"It depends on how experienced they are and how long they've lived here,” Reynolds said. “If they've lived here long, then they know a week of 60-degree days doesn't mean spring is here. You may be anxious, but you hold yourself back."
Reynolds recommends using a soil thermometer to check your soil temperature to decide whether to dig in. Soil rather than air temperature is the bellwether of whether to plant, he said. Seeds such as peas will germinate at an average soil temperature of about 50 degrees. Each species has different temperature requirements for germination. Generally, cool-season plants can survive air temperatures as cold as 28 degrees, Reynolds said.
Cover the new plantings with clear plastic to protect the soil from getting too saturated by rain.
Snow provides a nice incubator for new plants, acting as a blanket to keep the coldest air from penetrating, Reynolds said.
You can start hand weeding any time. Wait until plants have established themselves before fertilizing them.
As for gardeners in central and eastern Oregon, they're going to have to be patient. Direct seeding for cool-season crops is not possible until late April or May, said Amy Jo Detweiler, an Extension horticulturist in Redmond. Seedlings can be transplanted in May and June.
"We tell people that March is a good time to clean and sharpen your garden tools and take care of your houseplants," Detweiler said.
March is also a good time for high-desert gardeners to study seed catalogs and prepare seed tapes. Seed tapes are good for plants that require thinning, such as radishes. To make a seed tape, cut a 2- to 3- inch strip the length of a newspaper or use tissue paper strips, 2-3 inches wide and however long you need it, Detweiler said.
When it's time to plant, bury the seed tapes in the soil at the seed appropriate depth and the tissue paper or newspaper will break down into the soil, Detweiler said.