Like each of us, vegetables have their preferred seasons and they have many ways of showing us it’s either too cold or too hot for their ideal growing conditions. In USDA hardiness zones 3-8, early spring is an ideal time to sow vegetables that don’t like heat but it can be a challenging season to sow seeds. Cold soil, heavy rains, an occasional late frost, maybe even a dusting of snow are all factors of the spring season for those of us north of the Mason-Dixon line.
But gardeners are optimistic and eager if nothing else and so we sow.
Cold weather vegetables – peas, lettuces, greens, cabbage clan members – are also some of the most nutritious crops to grow and are made for immediate eating. I love growing heat-loving tomatoes, peppers, and squash but like any prima donna, they often require additional attention (work) after they have completed their performance on the garden stage. Cold weather vegetables can be harvested and prepared in less than 30 minutes.
There are a few tips for starting and growing cold weather vegetables:
- Most vegetables need full sun (6-8 hours) so observe your growing area to ensure it has enough sun each day.
- Create a soil with lots of organic matter (i.e., compost) because it will warm up quicker, drain better (from spring downpours) and offer a good foundation for plant growth. Raised beds are not necessary; simply create mounds to plant in.
- Mulch transplants with compost or straw to regulate moisture and soil temperature and protect from a late frost.
- Invest in a roll of reusable row cover to protect plants from a late or early frost.
- Plant early flowering herbs and flowers alongside the vegetables to help with pest management. Dill, cilantro, lemon balm, chervil, borage, and sweet alyssum will attract beneficial insects who will consume any undesirable insects who are interested in your early spring vegetables.
When To Plant Cold Weather Vegetables
The best time to plant in spring is dependent upon your zone, your weather, and the temperature of your soil. In general, wait until the soil is workable and outside temperatures rise above 40°F.
But soil temperatures are the more important factor and they should be at 50°F (10°C) for growth to happen. Soil thermometers are inexpensive but a digital meat thermometer with a long probe on it (often used when grilling) can be substituted. Be sure to insert at least 4-6 inches into the soil to get an accurate reading of the area where the roots of your seedlings will grow – typically called the root zone. When the soil temps are warm enough, transplant your vegetable starts after hardening off.
For a continuous harvest during spring and early summer, sow seed every two weeks until the heat arrives.
How to Sow Seed in the Spring
Sowing seed directly into the soil in unpredictable spring weather can be a frustrating experience. The combination of water-logged soil and spring showers can rot seed quickly. Incorporating several inches of compost into the top 6 inches of your bed will help with draining. Since most seeds are planted in the top ½ inch of the bed, the soil’s surface temperature is the more important factor.
Another option is to start seeds inside your home. Use a baking sheet to hold your 2 – 4 inch pots filled with compost or garden soil. Soilless sowing mixes can be purchased and they provide a sterile growing medium and are less likely to produce fungi or weeds. The goal is to provide a stable germination environment for the seeds and then move them ASAP to the growing bed so I have found screened compost to work fine.
What is Hardening Off?
Hardening off vegetable starts is an important step for seedlings that have been enjoying the warmth of indoors. They need to build up their hardiness, and I start by moving them outside, in the elements (no freezing temps) each day for a week. Toward the end of the week, I let them spend the night outside for a couple of days. It is important to keep track of the weather during this period; an overnight hard freeze may kill your otherwise hardy cool-season starts. But letting them spend the night outside at the end of their hardening off week is a good idea.
Once the seeds have germinated and seedlings have been hardened off and if outside temps are consistently above 40°F and your soil has warmed to 50°F then they are ready to go into the spring beds.
How to Protect Your Spring Seedlings
Each year the weather seems less predictable than the year before. I have had snow on May 4 and a hard frost on May 30th (which killed most of my newly planted tomato, pepper, and squash starts). Protecting seedlings is part of the early spring gardening game.
A glass cold frame can be purchased or created using recycled materials. Several years ago, I picked up two used patio doors left at the end of a driveway and one of them is now the glass cover on a raised bed I use for lettuce. Glass cold frames and the old-fashioned glass cloches do need to be monitored daily so that the humidity and heat can be managed.
Plastic 1-gallon milk containers that are “clear” (not solid white) can also be used as cloches. Cut off the bottom, remove the lid, and place the containers over individual seedlings. These work well but can be easily blown away.
Floating row cover is a lightweight white polyester fabric that can be floated on curved wires, creating a small tunnel. The row cover comes in different thicknesses that provide varying levels of protection against cold weather. Both light and water can filter through the material. Another benefit is that it keeps insects out when tucked into the beds. The material is reusable if handled carefully.
Gardening Extension: Autumn
Many gardeners forget the third season of growing: the autumn cold vegetable season. Counting back from your average first frost date, sow seeds, or seedlings in late summer. As nighttime temps begin to dip, use the tunnels or plastic cloches to protect your fall crop.
Cold Weather Vegetables for Spring & Fall
Sow seed lightly over a bed and keep moist for germination (7-14 days). Once seedlings appear, mulch lightly to keep moist. Harvest individual young leaves for salads or pull the entire plant when the rosette is mature (25-35 days). There are three types of spinach: savoy, which has dark, crinkled, and slightly curled leaves, flat-leaved, which has smooth broad leaves, and semi-savoy, which is a hybrid of the two. Spinach can also be started indoors and transplanted.
Lettuce loves cool weather and is easy to grow. Direct sow the tiny seeds four to six weeks before your average last frost date. There’s an abundance of varieties (romaine, butterhead, loose-leaf, and crisp-head) and I dedicate one bed to successive planting of lettuces. For a continuous harvest during spring, sow seed every two weeks until the heat arrives. Don’t bother sowing once temps hit the 80s; lettuce won’t germinate and some of your growing lettuce will bolt and turn bitter.
Keep moist during germination (7-14 days) and begin harvest at about 25 days by cutting small leaves. If you planted lettuce that grows into a head, allow it to form until you can’t wait any longer, and then harvest the entire plant.
Easy to grow and quick to harvest! Delicious in salads, as a quick snack or fried in butter, and layered onto a baguette with some fresh dill leaves!
Direct sow seeds and count the days – approximately 22-25 days for the small round types. There are many varieties so buy a variety and try out the subtle taste differences and varying sizes. Radishes are the perfect introduction to growing vegetables for the small hands of children.
Greens (Swiss chard, bok choy, mustard greens, tatsoi, & kale)
All of these greens are incredibly easy to grow and highly productive if regularly harvested. Kale seems to be the hardiest in my garden, often surviving through a snowy and frozen winter, looking a bit bedraggled in the spring but is alive.
Kale can be sown directly. I tried the Red Russian kale variety but am going back to the Lacinto variety this year.
Several years ago, I had an infestation of leaf miners in my garden beds which I discovered when I tried to grow Swiss chard and spinach leaves – members of the Chenopod family. Leaf miners are the larvae of several insects that burrow into the leaf tissues (mining), leaving behind a tunnel of destroyed leaf tissue as they eat. They are difficult to eliminate garden beds so I switched to greens that are from a different family.
Grow tatsoi much like you grow spinach – either direct seed or as starts. It is a bit pickier about drainage so if your soil is very wet, create 6-inch tall mounds and plant into the mounds. If tatsoi is exposed to extreme cold, it may bolt. Leaves can be harvested as early as 21 days from sowing seed. Tatsoi can be started indoors and transplanted.
Mustard greens must be only one generation removed from the weed category! They germinate quickly and grow like a weed. Younger leaves are mixed with lettuce for a delicious salad. Older leaves have a very sharp taste but work in a stir fry or mixed with kale in a saute.
Peas prefer to be direct sown and can be planted as early as February. They do require a trellis of some kind to climb up so have that in place when you sow. There are many varieties and maturity ranges from 70-90 days. Harvest the pods from the bottom as they mature first.