The official start of summer is near and now is the time to ensure your garden is ready before those sky-high Texas temperatures arrive.

“It may seem like a challenge to keep your garden beautiful in the summer, but with a little planning ahead, you can keep it producing and colorful,” said Larry Stein, Ph.D., Texas A&M AgriLife Extension Service horticulture specialist at Uvalde and professor in the Texas A&M College of Agriculture and Life Sciences Department of Horticultural Sciences.

A white plastic bucket filled with freshly picked okra
Gardeners who want to enjoy their own okra should plant them now. (Laura McKenzie/Texas A&M AgriLife)

As tempting as it may be to remove flowers as soon as they are no longer blooming, Stein said to allow foliage of spring-flowering bulbs to mature and yellow before removing. He also said gardeners need to “like ugly a little bit longer,” be patient with their wildflowers and make sure the seed heads are brown and mature before shredding.

Stein said gardeners should also critically examine their landscapes during the height of summer development. Think of your yard as an extra room of your house that you want to be able to enjoy with friends and family. Make notes of how you think it can be better arranged, plants that need replacement and overgrown plants that need removal.

Use mulch to protect moisture

During the summer, soil moisture becomes extremely important and essential for good plant production. Because continual watering is oftentimes costly and time-consuming, it pays to conserve the moisture around plants. This is best done by mulching.

“A good mulch will retain valuable moisture needed for plant growth and improve overall gardening success,” Stein said. “Mulches are usually applied 2 to 6 inches deep, depending on the material used. In general, the coarser the material, the deeper the mulch. For example, a 2-inch layer of cottonseed hulls will have about the same mulching effect as 6 inches of oat straw or 4 inches of coastal Bermuda hay.”

You can purchase mulch or make it using organic materials on hand or readily available in your region. AgriLife Extension offers an easy guide to mulching.

Top garden tips for May

Stein offered the following tips for gardeners this month.

A trio of ripe peaches on tree branches.
Make sure to keep an eye on early-maturing peaches and berries so you can pick them before birds get to them. (Michael Miller/Texas A&M AgriLife)
  • It is not too late to sow the seeds of sunflower, zinnia, morning glory, portulaca, marigolds, cosmos, periwinkles and gourd seeds directly into the soil. Achimenes, cannas, dahlias and other summer-flowering bulbs can also be planted in May.
  • Pinch back the terminal growth on newly planted annual and perennial plants. This will result in shorter, more compact, well-branched plants with more flowers. 
  • It’s time to plant caladium tubers, impatiens, coleus, begonias and pentas in shady areas.
  • Replace or replenish mulch materials in flower beds and shrub borders to conserve moisture and reduce weed growth. 
  • Take cuttings of your favorite chrysanthemums and root them in a mixture of sand and peat moss. Cover the cutting box with plastic and place it in a shaded area for five or six days to prevent wilting. 
  • Prune climbing roses as they complete their spring bloom season. Remove dead or weak wood as needed. 
  • Check for insects and diseases. Destroy badly infested plants. Spider mites can be especially troublesome at this time. Select a chemical or organic control or use insecticidal soap. 
  • Harvest your vegetables promptly so they do not get too big. Eating quality is much better if you harvest when the produce is small. Some refer to picking them small as “baby vegetables.” Harvest your onions as the tops fall over. Ideally, tie the spent tops together and hang them in a dry, cool place.
  • Be on the lookout for the ripening of early maturing peaches and blackberries; if you are not vigilant, birds will often get them before you know they are ripe.
  • Side-dress your tomatoes, peppers and even eggplant with fertilizer as they set fruit to encourage additional growth and more fruit set.
  • If you are a fan, it is prime time to plant okra, but remember it needs full sun and plenty of space between plants, about 2 feet.
  • Now is also prime time to bud and/or graft trees. Go to the Aggie Horticulture YouTube channel for how-to videos.

Give mystic spires blue salvia and Bougainvillea a try for summer

Stein suggests gardeners add Texas Superstar mystic spires blue salvia to their yard and/or experiment with a container of Bougainvillea this summer.

Mystic blue spires salvia plant with purple-blue clusters of flowers and green leaves.
Texas Superstar mystic spires blue salvia will bloom all summer with the proper care. (Texas Superstar)

“Improved mystic spires blue salvia was one of the best Texas Superstars we have ever released,” he said. “It blooms prolifically all summer with an occasional removal of spent flowers needed and comes back with elegance each spring.”

Mystic spires blue salvia is a compact form of another popular salvia called indigo spires. Though shorter than indigo spires, mystic spires flower even more frequently during the growing season. It produces masses of blue flowers that work nicely with other annuals and perennials. This Texas Superstar was improved years ago to shed dead petals to keep a cleaner look in the garden. Now all mystic spires blue salvia sold are this improved variety.

The perennial averages 18-30 inches tall and can be grown in containers, but it is typically used in bedding and perennial borders. It is also popular as a cut flower. It adapts to most Texas soils but needs good drainage. It is also tolerant of heat and both low and high humidity and is not typically bothered by pests, disease or deer.  

Another plant to consider adding to your garden – especially in a container – is Bougainvillea.  A container allows you to move the plant as needed and can add to the stress it needs to bloom. These plants flower best under stress – which is accomplished by keeping them slightly on the dry side and allowing the plant to become root-bound.

The tropical vine has sparse leaves and small, plain flowers. What gives this plant its colorful punch is its bracts which can be anywhere from yellow to orange to green to pink to purple to magenta. A bract is a modified or specialized leaf, and the Bougainvillea has triple bracts surrounding its flower.

“Bougainvillea is a plant that prefers hot and dry conditions,” he said. “Full sun and a rest period without too much watering are usually necessary before a burst of new blooms.”

Stein said any well-drained potting soil mix is suitable for growing Bougainvillea. They are rarely bothered by insects and a few aphids can be treated with the appropriate pesticide.

These plants do best in large clay containers if grown outdoors or in large hanging baskets. Hanging Bougainvillea are typically sold in 10-inch baskets but will do better in a 12-inch basket. Place the containers in full sun, or at least a half-day of full sun.

If a Bougainvillea is not blooming, it probably needs more sun or fertilizer. The vines are heavy feeders and ideally need almost constant feeding with a half-strength water-soluble fertilizer.

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