Gardening Tips for May


Tyler Rose Garden coming into full bloom.

Tyler Rose Garden coming into full bloom.

The saying is, “If you don’t like the weather in Texas, wait a minute and it will change.” After hitting the upper 80’s, it’s predicted to be in the upper 30’s tonight. Of course, weather, including temperature, humidity, rainfall, wind, etc., affects plants in many ways. Eventually spring will give way to our typical Texas summer with endless hot days and warm nights.

Many plants, including our turfgrasses, grow best in warm to hot temperatures. They have been slow in the transition from their winter dormancy to full growth. Pushing them with fertilizer is not the answer. Once it stays consistently 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.

A reminder that the annual Home Garden Tour, also sponsored by Smith County Master Gardeners, is June 1. For tickets and other information, go to and look under “Coming Events”. Click here for a tour flyer.

Scene in the Heritage Rose Garden in the Tyler Rose Garden

Scene in the Heritage Rose Garden in the Tyler Rose Garden

The Tyler Rose Garden is in glorious color now and well worth a trip to see. Besides the main rose garden display and the IDEA Garden, be sure to also visit the Heritage Garden in the southwest corner – I’ve never seen it so pretty as it is right now! Another newly renovated small garden to look for is the Sunshine Garden on the south end of the main rose garden display area.

The Vegetable Garden. 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 which put up a flower stalk will have a hollow center and will not keep very long, so eat them first.

Flowers. 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.

Close up of Torenia or wishbone flower. Look closely and you'll see the wishbone inside.

Close up of Torenia or wishbone flower. Look closely and you’ll see the wishbone inside.

Some other annuals to try in your garden this summer include wishbone flower (Torenia), fanflower (Scaevola), summer snapdragons (Angelonia), floss flower (Ageratum), or heliotrope. 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).

Colorful caladiums brighten shady spots, especially when planted in large drifts.

Colorful caladiums brighten shady spots, especially when planted in large drifts.

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.

Pests. Nip weeds in the bud by controlling them early in their development. Young weeds are easily hoed or pulled out of a garden or flower bed. Realize that the act of hoeing also stirs up the soil and brings more weed seeds to the surface. Now is the time to apply a layer of mulch, such as straw, leaves, bark or wood chips, etc. to the surface of the soil. This layer blocks out sunlight that triggers weed germination. Your plants will also appreciate the mulch because it greatly reduces water evaporation from the soil.

Check azaleas for lace bugs. These are small, slow moving, black insects with clear, lacy wings that feed on the underside of the leaves, leaving shiny black specks of droppings. Damage to the leaves, which look stippled or bleached, is usually worse on stressed azaleas and those receiving more hot, direct sun. Monitor new growth for current insect activity, since the older leaves will not turn back green.

Aphids (sometimes 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 regularly with a strong stream of water – or use an insecticidal soap or pyrethrin as low toxicity options.

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