June Gardening Guidelines

by Keith C. Hansen, Extension Horticulturist, Smith Co. – Tyler, Texas

School’s out, it’s getting hotter and summer time activities are getting into full swing. June brings both the opportunity to plant summer color, and the routine garden maintenance of mowing and weeding. This spring’s plentiful rainfall has hopefully helped our lawns, trees and gardens to begin to recover from last year’s extreme stress. Take advantage of the longer days by doing gardening tasks in the morning or evening when it is more pleasant to be outside. To keep the lawn and garden looking great, here are a few tips for this June.


Hotter weather means grass will be growing faster. Keep up with the mowing so you don’t have to bag the clippings. That may mean mowing every 5 or 6 days instead of every 7 to 10 days. Letting the clippings fall back into the lawn recycles nutrients but does not promote thatch. Keep the mower blade sharpened. Mowing frequently at the correct height will promote a healthy, thick turf that is resistant to weeds.

For St. Augustine or Bermuda lawns making poor growth thus far this year, make a second application of fertilizer. For best results, use a fertilizer with a high percentage of slow- release nitrogen so the grass won’t grow quite so rapidly. Be careful to not apply too much fertilizer.

Warning! A wet, rainy June and lushly growing grass from high rates of nitrogen can lead to grey leaf spot, a fungal disease of St. Augustine grass. Symptoms include grey lesions outlined in black on the leaf blades. Severe infestations result in a “melting away” appearance, with the leaves collapsing, quickly decaying, exposing the soil underneath. Areas staying wet, in the shade, in low spots, frequently watered, infrequently mowed and recently fertilized are the most prone to grey leaf spot.

Centipede lawns fertilized earlier this year do not need to be fertilized at this time. Wait until fall for the next application.

As spring rains slack off and give way to drier days, apply supplemental water as needed. The rule of thumb is to water enough to wet the soil 5 to 6 inches deep. Do not water too frequently. Shallow, frequent watering promotes a shallow root system that is more susceptible to the stress of summer heat and winter cold.


The best way to conserve moisture in the landscape is by mulching. Pine bark, pine needles, cypress bark, composted grass clippings and shredded leaves are among the materials suitable for a mulch. A three to four inch layer over the root zone retains moisture, keeps the soil cooler and helps prevent weed seeds from germinating under your shrubs, trees and flowers.

As you check your shrubs, ground covers and flower beds, watch for seedling trees, such as oak, hickory and pecan. They are more easily pulled when young, and an old pair of pliers will help you get the grip needed close to the ground to pull up root and all. They are also more easily extracted when the soil is moist.


June is a great month for setting out colorful summer annuals. For large areas, try directly seeding zinnias, cosmos, gomphrena or portulaca. There are several others you can set out now as transplants including marigold, salvia, gaillardia, petunias, purslane, verbena, dusty miller, lantana, ageratum, amaranthus, gomphrena (globe amaranth or batchlor’s buttons), celosia, Texas bluebells (or lisianthus), cockscomb, and firebush. Plant copper plants now in a sunny spot for a beautiful display this fall.

Color for shady areas include caladiums, coleus, impatiens and bedding begonias. Try nicotiana and coleus in partial shade, or for full sun the two Texas SuperStars (TM) SunColeus varieties ‘Burgundy Sun’ and ‘Plum Parfait’.

Many nurseries now have a great supply of perennials to brighten the summer garden. Look for perennial hibiscus, canna, daylilies (select soon for the color you want), yarrow, summer phlox, salvia, perennial lantana, montbretia, Rudbeckia ‘Goldstrum’ and purple coneflower.

Plant mums now for fall bloom. Pinch back established mums, along with other fall bloomers like Mexican mint marigold, Mexican bush sage (Salvia leucantha) and autumn asters to encourage compactness and more flowers.

Water transplants before you plant and then again afterwards. The soil should be well- prepared with additions of organic matter, and well-drained. Apply a diluted solution of water-soluble fertilizer at planting and then regularly once plants begin to put on new growth. Remove faded blooms to encourage new growth and repeat bloom. A layer of mulch will conserve water and prevent weeds.

Summer tropical plants, though they are not freeze hardy, are perfectly at home in our East Texas heat and humidity. Plant them in the ground for quick growth or plant in pots or tubs so you can overwinter them indoors. Some of the best include tropical hibiscus, penta, oleander (semi-hardy), bougainvillea, mandevilla vine (spectacular!), agapanthus, trailing lantanas, allamanda vine and plumbago. These sun and heat lovers will quickly brighten up your yard and give a great display all summer and fall.


Be sure to mulch your roses to conserve moisture and keep down summer weeds. Continue a routine spray program to control blackspot, and watch for insects and mites. Remove flowers as they fade and feed regularly to encourage new blooms.


Apply a four to six inch layer of pine needles or other mulch to conserve water around these shallow-rooted shrubs. Feed them very lightly with a complete fertilizer to encourage production of new growth. Watch out for spider mites and lace bugs which feed on the underside of leaves. Their piercing and sucking causes the leaves to look stippled and bleached or bronzed.


One of the most common tomato disorders is blossom end rot. This is not a disease but a physiological problem caused by a lack of calcium and fluctuating soil moisture. Keep the soil evenly moist, mulch to conserve moisture and lime the soil before planting the next crop to provide calcium. Blossom end rot usually only affects the first tomatoes to ripen.

Spider mites can occur on tomatoes, roses, junipers, marigolds and other ornamentals now that the weather is hot and dry. Look for stippled leaves, and under severe infestations, fine webbing. Spider mites can be detected by taking suspicious leaves and rapping them over a white sheet of paper. Any dots which move are probably mites. Light infestations can be reduced by frequently syringing leaves with a sharp stream of water or using insecticidal soap. For more severe problems, use an approved miticide.

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