May marks a significant transition in the Texas gardening calendar, shifting toward the intense heat of summer. This period is the final opportunity to establish warm-season crops and ornamentals that thrive under prolonged sun exposure and high temperatures. Success requires focusing on heat tolerance and quick establishment before the most severe summer weather arrives. Regional planning is essential due to the state’s vast climatic variations.
Understanding Texas Planting Zones
The size of Texas means that gardening is not uniform, encompassing USDA Hardiness Zones from 6b in the Panhandle to 10b along the Gulf Coast. May planting schedules must be customized based on these distinct regional climates.
The state is broadly categorized into three major regions for May planting. South Texas and the Gulf Coast (Zones 9-10) are already experiencing summer conditions, meaning only the most heat-tolerant plants should be started. Central Texas and the Hill Country (Zones 8-9) are in a rapid transition phase, requiring heat-loving plants to be established quickly. North Texas and the Panhandle (Zones 6-7) have a slightly longer window, allowing for the planting of warm-season vegetables that require a full summer to mature.
Heat-Tolerant Vegetables for May Sowing
May is the time for direct-sowing vegetables that require intense heat to germinate and produce a harvest. Southern peas (cowpeas or black-eyed peas) are excellent choices because they tolerate high temperatures and require less water than many legumes. Okra thrives in Texas summer heat, but daily harvesting is necessary to prevent the pods from becoming fibrous.
Plant sweet potato slips this month, as the tubers require the full hot season to develop before a fall harvest. For vine crops, direct-sow seeds for watermelons, cantaloupe, and pumpkins early in the month. Traditional tomatoes may stop setting fruit when night temperatures remain above 75 degrees Fahrenheit, but gardeners can plant heat-set varieties like ‘Solar Fire’ or ‘Heatwave’ now for continued production.
Peppers and eggplant are warm-season vegetables that thrive in May plantings, though transplants are best for a head start. Look for Asian eggplant varieties, which are resilient in high Texas heat. Malabar spinach, a heat-loving vine, can substitute for traditional spinach, which bolts quickly in warming temperatures.
Annuals and Perennials for Summer Color
May is the time to install heat-loving annuals and resilient perennials for continuous landscape color through the summer.
Annuals like Cora XDR Vinca (periwinkle) are recommended because they are bred for disease resistance and thrive in hot, humid conditions. Zinnias are prolific, drought-resistant bloomers that quickly establish and attract butterflies. Other dependable annual choices include portulaca and moss rose, which endure dry conditions and intense sun. For shade, plant caladiums, which provide colorful foliage in areas shielded from the afternoon sun.
Perennials like Lantana provide extended bloom time and attract hummingbirds and butterflies. The shrub-like perennial Pride of Barbados (Caesalpinia pulcherrima) handles high heat and produces vibrant red and orange flowers. Daylilies and Purple Coneflower (Echinacea) are low-maintenance perennials that establish well in May and tolerate a wide range of soil and sun conditions.
Strategies for Successful May Planting
The immediate challenge for May planting is mitigating heat stress on newly set roots and seedlings. Applying a thick layer of organic mulch, such as shredded bark or composted material, is essential. A layer two to three inches deep stabilizes soil temperature, keeps roots cooler, and reduces water evaporation from the soil surface.
Watering practices must adapt to the increasing heat, moving away from light, frequent sprinkles. New plantings require deep, infrequent watering in the early morning to encourage the development of deep root systems. Delivering water directly to the root zone with soaker hoses or drip irrigation minimizes water loss and prevents wet foliage, which can encourage fungal diseases.
Soil preparation is necessary to maximize water retention before the summer drought begins. Incorporating compost and other organic matter into the planting beds improves the soil’s structure, allowing it to act like a sponge. Well-nourished soil provides plants with the resilience needed to withstand the stress of high temperatures, ensuring a vigorous start for May plantings.