Cool spring beckons gardening season

Published on Thursday, 1 May 2014 00:27 - Written by Keith Hansen, Keeping It Green

It seems like our spring is similar to this time last year — very cool. Overnight temperatures in the 40s and mild daytime temperatures will help keep blooms brighter and longer. But the cool weather also slows down the rate of growth of all kinds of plants that thrive during the warm summer season.


Garden centers are overflowing with new and fresh plants for the garden. Early May is a great time for setting out new annuals to take the place of winter color. And the number types and varieties of colorful perennials available for adding color and interest to the garden increases every year.

This cool spring has prolonged the display of cool-season plants, but it’s getting time to replace pansies with heat-loving plants. Sow seeds of sunflower, zinnia, celosia, cockscomb, morning glory, portulaca, marigold, cosmos, periwinkles, gomphrena, cleome (spiderflower) and gourds directly into the flower bed.

Some other annuals to try in your garden this summer include wishbone flower (Torenia), fanflower (Scaevola), summer snapdragons (Angelonia), floss flower (Ageratum), or heliotrope for a nice blue color. Think about using some tropical flowering and colorful foliage plants, such as copper plant, mandevilla, allamanda (golden trumpet), or sweetpotato vine (give them plenty of room to spread).

For shady spots, use these color plants: New Guinea impatiens, annual salvia, coleus, caladiums and begonias. Flowering tobacco (Nicotiana), and pentas are great fragrant annuals for partial shade.

Be sure your garden, flowers and shrubs have a layer of mulch over the soil surface to reduce weed growth and to conserve water. Pine needles, pine bark, hardwood chipper mulch and shredded leaves are examples of mulching materials.


Once tomatoes and peppers begin to set fruit, lightly apply nitrogen fertilizer (called side dressing) every couple of weeks. This supplemental feeding keeps the plants vigorous and growing, allowing them to set and mature the maximum amount of fruit. Mulch around tomatoes to maintain even soil moisture. This will help to reduce blossom end rot problems.

Cool-season vegetables like lettuce and spinach will begin bolting (flowering) and quickly go down in quality. Harvest them soon and replant empty spots with warm-season vegetables like okra, sweet potatoes, pumpkins or watermelons.

Onions will be ready to harvest after their necks soften and the leaves fall over. Stop watering when that happens. Pull the bulbs, and let them dry in a shady, airy location. Once the tops have dried, clip the roots and tops, leaving about 1 inch above the bulb. Onions that put up a flower stalk will have a hollow center and will not keep very long, so eat them first.


May is an ideal time to plant a new lawn, or repair spots that died over winter. St. Augustine, Bermuda, zoysia and centipede can all be established quickly with the warmer spring temperatures, yet it is not so hot that watering becomes a great chore.

Many plants, including our turfgrasses, grow best in warm to hot temperatures. They have been slow this year in the transition from their winter dormancy to full growth. Pushing them with fertilizer is not the answer. Once it consistently stays warm, grass growth will get into full gear. That is the best time to make your first application of fertilizer, and since centipede and zoysia grasses are typically slower to get going in spring, we recommend waiting until May to feed these lawns.

For longer lasting results, and to avoid promoting lush, disease-prone turf, use a fertilizer with a high percentage of the nitrogen in a slow release form. The benefit to the lawn far outweighs the few cents more it may cost. In the absence of a soil test, use a 3- to-1-to-2 or 4-to-1-to-2 ratio fertilizer.


As the growing season progresses, plant pests seem to proliferate. Aphids (often called plant lice) are common pests on many types of plants, both vegetable and ornamental. While a couple of aphids are no big deal, they multiply faster than rabbits, and can quickly cause deformed and stunted new growth. Blast them off with a strong stream of water, or use an insecticidal soap or pyrethrin as low toxicity options.


The Smith County Master Gardeners will continue the First Tuesday in the Gardens series next Tuesday, May 6, with a program on attracting hummingbirds and butterflies. This free program will be conducted during the noon hour in the IDEA Garden, located in the southeast corner of the Tyler Rose Garden. Seating is limited, so bring a lawn chair if you have one.

The East Texas Garden Lecture Series also continues this month with a program on learning how to install a drip irrigation system for your landscape, garden and/or potted plants. This morning session starts off in the Tyler Rose Garden Center at 9 a.m. where Brad McCullough, manager of Ewing Irrigation, will talk about the principles and practices involved in using this water-saving technique, and then head out into the garden where you can see firsthand how it is done. Cost is $15, and registration opens at 8:30 a.m.

A reminder that the annual Home Garden Tour, sponsored by Smith County Master Gardeners, is June 7. Four fabulous home gardens will be open for one day only for your viewing inspiration and enjoyment. For more information, go to and look under “Coming Events.”

Keith Hansen is Smith County horticulturist with the Texas A&M AgriLife Extension Service. His web page is His blog is