By Jan Birdsall, UC Master Gardener of Placer County
From The Curious Gardener, Winter 2021
This season instead of sugar plums dancing in their heads, gardeners tend to lean towards thoughts of their next gardening opportunity. Don’t discount planting in the late winter/early spring months, so that you and your family can enjoy colorful cool season vegetables, which have become very desirable in the last several years. There are several wonderful advantages to planting a vegetable garden during this time, including fewer insects to contend with, rainfall to help with watering, and various winter vegetables that offer more colorful produce to brighten anyone’s garden.
When planning your garden, explore unique varieties of purple or maroon kohlrabi, cabbage, cauliflower, lettuce, onions, turnips or ornamental kale (decorative but not edible). In addition, veined Swiss chard, beets, shallots and radishes add a splash of red. Many types of gourmet carrots and beets come in orange, purple, gold/yellow, white or, in the case of beets, candy stripped red and white. With a few splashes of green kale and lettuces, this completes a delightful palette of colors in your garden. Ask friends and neighbors about their experiences growing unique late winter or early spring gardens, including their insights and recommendations.
Many of these unique seeds and transplants may be available through your local nursery, reputable seed catalogs and/or online nurseries. In our area, we have a unique source of free non-GMO seeds at the Loomis Seed Library located at the Loomis Library. Some intriguing seeds listed are star kohlrabi (Kohlrabi ‘Azure Star’), rainbow carrots, (Daucus carota) and white globe turnips (Brassica campestris ‘Top White Globe’).
Late winter/early spring vegetables are considered cool season plants that thrive nicely in soil temperatures between 55° to 75° and in many cases handle some frost. Remember even if your soil temperature is above 55° plants do not grow when daylight hours fall below 10 hours a day. So do not plant too early without a supplemental light source. On the other side of the spectrum, warmer soil temperatures over 75° can cause these plants to “bolt”—basically going to flower and seed rapidly without investing energy in producing the vegetable, which usually becomes bitter to the taste. Ultimately, determining planting time for these vegetables is a balance.
Here in the foothills of Placer and Nevada counties, we are blessed with soil temperatures in this cool range or higher almost year-round (except December, January and some or all of February), especially if you use “cold frame” gardening or have a heated and lighted greenhouse. If you have raised beds, simply placing a used window (preferably safety glass) or framed transparent heavy mil plastic sheeting over your bed’s area will work. Make sure whatever you use, it can be easily propped up to provide circulation, watering, and the release of heat. Remember, in times of forecasted frost conditions, keeping your plants well-watered will protect them. Wet soil captures the radiant heat during the day and then releases it at night as it freezes. In addition, many cool season plants work well in containers so that you can place them in a protected sun-drenched southern location preferably near your back door.
The first step is determining the earliest dates you can plant your cool season vegetables in the calendar year. Luckily, there is a Placer County Master Gardeners chart for that! Refer to the second page chart, “Cool Season Vegetables.” As you see on the instructions to the left of this chart, it is calibrated for 1200' elevation. Follow the instructions to adjust the chart contents to your elevation. The results tell you approximately when to start seeds indoors, direct sow seeds in garden, plant transplants and harvest your produce. Don’t forget to refer to your seed package for specific information. Of course, be aware if it is unseasonable cold and adjust the planting time. If you are unsure, for under twenty dollars you can buy a soil temperature gauge and take readings in several areas where you plan to plant.
Here are some cool season vegetables tidbits and planting information:
Kale (Brassica oleracea) becomes sweeter when kissed by a frost so planting in late winter is a wonderful time to plant and enjoy this nutrition packed vegetable for you and your family. It can be planted from seed or transplant. There are many varieties but they can be grouped by type of leaf, curly or plain. Plant in moist soil about 12 inches apart. Water immediately and continue to do so after checking soil moisture every few days. You can harvest individual leaves when plant is approximately 8 to 10 inches high. If you want to harvest the whole plant, you can cut the stem 2 inches above the soil, and it will sprout new leaves in one to two weeks. Once it gets hot outside, kale will become bitter.
Likewise, lettuce (Lactuca sativa) also becomes extremely sensitive to high temperatures and will become bitter. It can be planted from seed or transplant, spacing them 4 to 6 inches apart. Most gardeners plant the leaf type, and some varieties harvest as soon as 30-45 days. Determine days to harvest from seed packets. Keep lettuce watered since it is composed mostly of water and needs to grow in soil that remains moist. When the plant is approximately 6 to 8 inches high, you can harvest the outside leaves, however unlike kale, head lettuce will not regrow once you cut off the plant.
Potatoes (Solanum tuberosum) are extremely appealing to young children because they are easy to sow, watch grow and harvest. Do not use potatoes from the market as they are usually treated with a growth stopping chemical. Instead use certified seed potatoes and plant them in early spring. Cut in “bud” sections, dry one day and plant the bud 3” deep and 6- 12 inches apart in well-drained mounds of soil but keep moist. Harvest at desirable size.
Finally, carrots (Daucus carota) have an incredible array of colors to choose from and come in varieties that grow very short to very long. Make sure your area of garden soil has been loosened deeply enough to accommodate the mature length of the carrots you choose to grow. Check seed packet instructions on length of carrot at maturity and number of days to harvest. When seedlings are approximately 2 inches tall, you may need to thin or pull out stems in order to give carrots room to grow to maturity. They need at least 2-4 inches between plants. Keep moist and water when the top inch of soil feels dry to your finger. Harvest when carrots are mature.
One of the thrilling parts of having a late winter/early spring garden is seeing the vegetables mature, and the color-filled garden in an otherwise dull winter landscape. Start planning now.
References
Ingram, Roger and Kelley Brian, Michele Fisch, et al. Bountiful Harvest Family Garden Guide Late Winter & Early Spring Planting. University of California Cooperative Extension Nutrition BEST. 2015. https:// ucanr.edu/sites/Nutrition_BEST/files/220881.pdf
Geisel, Pamela M and Carolyn L. Unruh. Vegetable Garden Basics. University of California Agriculture and Natural Resources. Publication 8059. 2002. https://anrcatalog.ucanr.edu/pdf/8059.pdf
Links update 12/7/2025