May Gardening Checklist for Central Texas


May is the month for Texans to continue enjoying spring flowers and begin harvesting ripe tomatoes. Warm season annuals are showing up at garden centers, there are summer vegetables to plant and hot weather perennials leap into full flower this month. With the official first day of summer still a few weeks away, enjoy the last half of spring, the bounty of your spring garden and begin to prepare your landscape for warmer temperatures. In fact, I have a blog with six tips on how to take care of plants in hot weather. You will find it here.

What to Plant in May in Texas?

Plant warm season annuals – angelonia, celosia, coreopsis, gaillardia, gomphrena, portulaca, purslane, vinca and zinnia. For shade to light shade plant begonia, caladium, coleus, impatiens and pentas.

In flower beds, sow seeds of cockscomb, gomphrena, sunflower and zinnias. Fill hanging pots and containers for summer color with bougainvillea, caladium, coleus, geranium, impatiens, tropical hibiscus, mandevilla, penta, sweet potato vine and vinca. What vines to plant for summer? Both coral vine and hyacinth bean are two good ones that attract pollinators.

Culinary herbs to plant for Texas warm weather are basil, lemon balm, Mexican mint marigold, mint, oregano and rosemary. Plant turf (sod, seed or sprigs) into soil that is amended with compost, raked and graded for drainage.

Plant groundcovers, trees and shrubs. Also, plant herbaceous perennials that perform well in summer’s heat  – artemisia, bulbine, butterfly weed, coreopsis, Esperanza, fall aster, firebush, guara, Gregg’s mistflower, perennial hibiscus, lantana, plumbago, rock rose, Mexican bush sage, skullcap, society garlic and yucca. Plant ornamental grasses for summer to fall interest. Keep in mind, that new plant material takes time to establish. As temperatures rise, keep new plantings mulched and monitor soil moisture through the summer.

Move plants that have been overwintered indoors to patios and porches. Refresh the growing media of plants that remain indoors all year.

What Vegetables can be planted in April in central Texas?

Planting vegetables at the optimal time yields the best results. Keep this in mind if you plant a little early or late for your zone. For example, April is one of the optimal planting times for eggplant, peppers and summer squash. If you do plant in May, a tip is to use shade cloth over plants for the first 2 to 3 weeks to aid establishment. When growing vegetables, it is almost always better to plant early during the optimal time rather than later. The planting calendar I use is one that I produced with the Master Gardener volunteers in my training program. Here is the link to this resource: Link

The planting times for vegetables by seed or *transplant in May for zone 8b central Texas: 

Week 1 – corn, cucumber, *eggplant, melon – cantaloupe/honeydew; okra, peas-Southern, *peppers, pumpkin, squash – summer/winter, summergreens – Malabar/amaranth; sweet potatoes – plant slips; watermelon

Week 2 – *eggplant, melon – cantaloupe/honeydew; okra, peas- southern; *peppers, pumpkin, squash – summer/winter; summer greens – Malabar/amaranth; sweet potato slips; watermelon

Week 3 – *eggplant, melon – cantaloupe/honeydew; okra, peas – southern, *peppers, pumpkin, squash – summer/winter; summer greens – Malabar/amaranth; sweet potato slips; watermelon

Week 4 – *eggplant, melon – cantaloupe/honeydew; okra, *peppers, pumpkin, squash summer/winter; summer greens – Malabar/amaranth; sweet potato slips; watermelon

Adjust planting times for your USDA zone or check with your county Extension office for planting dates specific to your area.

Pruning and deadheading

Cool to warm season annuals begin to fade in May with higher temperatures. Some annuals that are spent may need to be removed like borage, calendula, delphinium, foxglove, larkspur, pansies, poppies, snapdragons and violas. If reseeding is desired for larkspur or poppies, leave plants in place until seeds have matured.

For early spring flowering perennials like salvia, prune away faded blooms. This increases the next set of flowers. Leave spring bulb foliage in place until it yellows, then prune. This allows the bulb to be replenished for next year’s flowering of bulbs that rebloom.

If oakwilt disease occurs in trees in your area, avoid pruning from February through June.


If you’ve not fertilized your lawn, do that in early May. Lawns in central Texas may also be fertilized in July and September. If you test your soil to learn the existing levels of nutrients, you can precisely apply fertilizer the turf needs.

For spring apply a product that is a combination of quick and time-release nutrients. The product label has this information, as well as the product analysis. Nitrogen (N) is the first number listed in the ratio and is the element plants need in the largest quantity. Most fertilizers also include phosphorous (P) and potassium (K), listed on the package in that order. In Texas, most soils have high levels of phosphorous – the middle number – and need very little or none of that nutrient.

Perennials and shrubs will benefit from fertilization early in the month with compost or a slow-release fertilizer. Annual flowering plants require a more immediate source, so a water-soluble fertilizer at half strength every 2 to 3 weeks promotes blooming.

How do you get rid of weeds in the spring?

The weeds in flower beds and lawns in spring germinated in the fall and winter. They are now mature and setting seed. In lawns, the best thing to do is mow. It is too late to apply a preventive pre-emergent for cool season weeds. Mowing should produce good results and prevent some weeds from setting seed.

In flower beds, pull weeds or hoe and apply a 2 to 3 inch covering of mulch to prevent germination of warm season weed seeds. Apply mulch around trees that grow in the lawn to prevent mower and trimmer damage to the trunk. Mulch vegetable gardens to prevent weeds, preserve moisture and reduce disease.


To prepare for summer watering, do a test run of your irrigation system. While the system is running, check water pressure levels and look to see if spray heads are too far apart, resulting in poor water distribution and dry spots in the yard. Also watch for sunken sprinkler heads that do not pop up properly; for misaligned spray patterns that throw water onto streets, sidewalks or driveways; and broken or missing sprinkler heads. Inspect and repair water hoses and hose end sprinklers. Here is a handy helper for hose end irrigation. Find a Smart Hose Faucet Timer Here.

Insects and Disease

With warmer weather, the insect and disease season begins in earnest. The best way to control pests is to inspect plants frequently. If discovered early, insects and disease are easier to manage.

In the vegetable garden, watch for early blight on tomatoes. Remove infected foliage to prevent spread and improve airflow. Look for hornworm on tomatoes that can be picked off. An option is to spray plants with Bt – Bacillus thuringiensis, a natural caterpillar control that is safe for crops. Inspect the underside of leaves for eggs and pests like stink bug that gather on stems.

Check new tender foliage for aphids and leaf footed bugs. Squash vine borers can devastate a crop. Cover plants with netting or wrap stems at the soil to interrupt the life cycle of the adult moth.

In lawns, Take All Root Rot (TARR) can develop this time of year in St. Augustine lawns. It is difficult to manage but a light application of Canadian sphagnum peat moss may provide some control. Brown patch in lawns is more common in fall, but might show up in spring. It may require a fungicide to manage. Water lawns very early in the morning rather than evenings to avoid fungal disease.

Grasshoppers have emerged and are smaller in spring. Use a natural product like Nolo Bait. Read and carefully follow instructions for use. With high humidity, powdery mildew on ornamentals may develop. It may be controlled with a natural fungicide.

May is the time to manage crapemyrtle bark scale. This scale is a sucking insect that feeds on plant leaves and stems. Evidence that the pest is present is black sooty mold that grows on honeydew – the excretion of the scale. This mold may cover foliage, stems and branches. Although the plant is not killed, the tree is unattractive. A soil drench insecticide in April or early May can be applied to manage this scale. For additional information go to this link:  CRAPEMYRTLE BARK SCALE

Roses that are exhibiting unusual growth may have rose rosette disease (RRD). This virus has been identified in central Texas. Infected plants exhibit elongated, concentrated growth that is twisted, reddish in color and has excessive thorns. RRD is transmitted by the eriophyid mite. Although research is ongoing, RRD has no known cure. Scientists and rose experts recommend to bag and throw away infected roses and all the roots. For additional information go to this link:  ROSE ROSETTE  

Manage fire ants with the ‘Texas Two-Step” method. For a schedule and current products to use, go to this link: FIREANTS  

You may also like