March marks the transition from winter into the vigorous growing season for Louisiana gardens. This month is often considered the official kickoff for planting, as rising soil temperatures and increasing daylight hours encourage growth across the state. Gardeners must act with purpose in March, balancing the final planting of cool-season crops with the eager introduction of heat-loving vegetables and ornamentals. Successfully navigating the unpredictable weather of this transitional period determines the productivity of the garden through the long, humid summer.
Understanding Louisiana’s Planting Zones
Louisiana’s expansive geography means planting times vary significantly depending on the region, a difference largely defined by USDA Plant Hardiness Zones. Most of the state falls within Zones 8 and 9, which reflect the average annual minimum winter temperature. Southern Louisiana, primarily in Zone 9, experiences a much earlier spring, while the northern parishes in Zone 8 maintain cooler temperatures later into the season.
The most important factor influencing March planting is the last expected frost date. In the warmer, southern parts of Louisiana, the last frost often occurs in late January or early February, making mid-March safe for planting tender annuals. Conversely, gardeners in North Louisiana typically wait until the end of March or even early April to be completely past the risk of a late freeze. Monitoring local forecasts for the 10-day outlook is prudent before transplanting any vulnerable warm-season crops.
Warm-Season Vegetables and Herbs for March
March is the prime time for introducing heat-tolerant crops, especially in Southern and Central Louisiana, where frost danger has largely receded. The most temperature-sensitive plants, such as tomatoes, peppers, and eggplant, should be planted from purchased transplants rather than seeds. These transplants benefit from the warming soil, allowing them to produce a harvest before the most intense summer heat arrives.
Other warm-season vegetables are best started directly from seed. Direct sowing is recommended for cucurbits, including cucumbers, summer squash, zucchini, cantaloupe, and watermelon. These plants generally dislike root disturbance, so planting seeds directly into warm, rich soil ensures a quick and healthy establishment. Corn, snap beans, and Southern peas are also direct-sown in March to benefit from early spring moisture and milder temperatures.
Warm-season herbs, which are essential to many Louisiana dishes, can also be planted now. Basil thrives in the March warmth and can be planted from transplants once nighttime temperatures consistently remain above 50°F. Herbs like mint, lemon verbena, and rosemary can be added to the garden or containers, provided they are given well-drained soil to prevent root rot in high humidity.
Spring Flowers and Cool-Season Crops
March is the final window for planting remaining cool-season vegetables before summer heat causes them to bolt. Root crops like carrots and radishes can still be direct-sown, along with leafy greens such as collards, mustard, and Swiss chard. These crops must establish quickly to complete their growth cycle before daily high temperatures climb into the 80s.
The ornamental garden receives an injection of color in March with the planting of annuals and perennials. Many cool-season flowers, such as petunias, violas, and pansies, may already be established from a fall planting, but a second planting in mid-March can extend their bloom period into early summer. The heat-tolerant Supertunia Vista series, for example, is often planted now to provide continuous color.
Annuals like cosmos, sunflowers, and zinnias can be direct-sown into the garden beds to thrive as the weather warms. These resilient, warm-season bloomers quickly establish in the spring soil. Planting these now ensures a vibrant display that handles the high temperatures and sun exposure of the Louisiana summer.