Early spring planting transitions the gardener from planning to active cultivation, maximizing the growing season. This period capitalizes on cool weather, favoring hardy, cold-tolerant plants. Establishing these plants before summer heat arrives leads to earlier harvests and longer bloom times. Success depends less on the calendar date and more on reading the actual conditions of the garden environment.
Understanding Early Spring Conditions
The determination of when to plant relies on factors beyond the average last frost date, which serves only as a general benchmark. Gardeners must use a soil thermometer to track ground temperature, as this is a more accurate indicator of readiness for seeds and roots. Most cool-season crops require the soil to be consistently above 40°F to 45°F for successful germination and initial growth. Planting in soil colder than this minimum risks slow or non-existent germination, leading to seed rot or weak seedlings.
Monitoring the workability of the soil is also important before planting. If the soil is too wet and forms a tight ball when squeezed, it is too saturated to be worked without damaging its structure through compaction. Waiting until the soil is damp but crumbles easily ensures that seeds and roots have the necessary aeration to establish themselves. Attention to soil temperature and moisture prepares the bed for robust early growth.
Direct-Sow Vegetables for the Chill
The earliest vegetables to plant are those that can be sown directly into the garden bed as seeds, thriving in lower temperatures and tolerating light frost. Spinach, for instance, is extremely cold-tolerant, capable of germinating in soil temperatures as low as 35°F. Radishes are also quick-maturing candidates, with seeds that germinate in soil around 40°F and produce a harvest in as little as three to four weeks.
Peas are an early spring crop, often sown as soon as the soil can be worked, requiring a minimum soil temperature of 40°F to begin germinating. Planting peas early allows them to mature before the summer heat causes them to stop producing. Carrots and beets can be direct-sown now, though they prefer a slightly warmer soil temperature of around 45°F to 50°F for a reliable start. Leaf lettuce varieties also enjoy this cool period, germinating reliably around 40°F, and can be harvested continuously by selecting outer leaves.
Cold-Tolerant Transplants and Sets
Certain cool-season crops are best planted not as seeds, but as small plants, sets, or tubers. Onion sets, which are small, immature bulbs, can be planted as soon as the ground is workable and are highly cold-tolerant, allowing them to size up before summer. Seed potatoes, which are small tubers, should be planted when the soil temperature reaches a consistent 45°F to establish roots before rapid growth begins.
Many brassicas, such as cabbage, broccoli, and cauliflower, perform best when planted as hardened-off seedlings. These transplants are started indoors to gain a head start, then gradually acclimated to outdoor temperatures over several days. Hardening-off prepares the young plants to withstand the fluctuating temperatures and stronger sun exposure of the early spring garden. Transplants should be placed in the ground when the soil temperature is around 60°F to 65°F to ensure strong root development.
Cool-Season Flowers and Ornamentals
The desire for color after a long winter can be met by planting specific flowers that tolerate or even require cool temperatures. These hardy annuals, often referred to as “cool flowers,” can withstand light frost and provide blooms weeks before traditional summer annuals. Pansies and their smaller relatives, violas, are excellent choices, as they flower continuously in the mild temperatures of early spring and fall.
Other cool-season ornamentals include snapdragons and calendula, which thrive in cooler soil and produce vibrant colors before the summer heat causes them to fade. Some flowers, like larkspur, benefit from being direct-sown in early spring, as their seeds require a period of cold to properly germinate. These additions provide immediate visual appeal and support the garden ecosystem early in the season.