By Nell Reed

Oklahoma Count Extension Master Gardener

The following list of tasks is taken from the OSU Extension Publication, HLA-6408—Landscape Maintenance Schedule, with additional information added. This maintenance schedule is a checklist which emphasizes prevention rather than remediation. Some of the topics mentioned below have individual fact sheets available at


Many perennial flowers will benefit from deadheading so their energy will be spent producing flowers rather than seeds.

Tropical plants such as hibiscus and mandevillas are available in nurseries now and do well in heat and humidity.

To keep your annuals blooming all summer, fertilize regularly. Petunias and calibrachoa will bloom all summer if given regular fertilization. Water soluble fertilizers work well for this purpose.

Once the outside temperature goes up, plants in pots should be watered daily if needed.

If you haven’t already mulched your flowerbeds, do it now. Mulching prevents weeds and keeps your plants cool.

Heat tolerant annuals include cuphea, lantana, pentas, periwinkle and zinnias. Periwinkles don’t like wet feet.

Annuals that like shade include caladiums, dragon wing begonias, impatiens, and torenia. Wax leaf begonia and coleus can do sun or shade White caladiums will brighten a shady area.


Fertilize warm-season grasses using one pound of actual nitrogen per 1,000 square feet.

Dollar-spot disease of lawns can first become visible in mid-May. Make sure fertilizer applications have been adequate before applying a fungicide. (EPP-7658)

Seeding of warm season grasses should be completed by the end of June to reduce winter kill losses. (HLA-6419)

Brown patch disease of cool-season grasses can be a problem. (HL-6420)

Continue to water deeply as needed. Apply at least one inch of water each time. Meet water requirements for TURF. (HLA-6420)

Post-emergent control of crabgrass and summer annual grasses is best performed on young crabgrass plants. (HLA-6421)


Vigorous, unwanted limbs should be removed or shortened on new trees. Watch for forks in the main trunk and remove the least desirable leader as soon as it is noticed. (HLA-6415)

Pine needle disease treatments are needed again in mid-June. (EPP-7618)


Softwood cuttings from new growth of many shrubs will root if propagated in a moist shady spot.

Shrubs that bloom in the spring may be pruned after they finish flowering, if needed. No pruning should be done after mid-June. Only prune if there is a reason.

If you haven’t fertilized your spring-blooming shrubs, you should do so now. One application a year is enough.


Remain alert for insect damage. Spider mites will cause the foliage of most plants to become pale and speckled; juniper foliage turns a pale yellowish color. Shake a branch over white paper and watch for tiny specks that crawl. Spider mites and aphids can be sprayed off with a hard blast of water. Be sure to spray the undersides of the leaves.

Watch for first generation fall webworm. (EPP-7306)

Continue to inspect for bagworms on juniper and arborvitae. They can often be removed by picking them off.

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