Lawn and Turf
· Remove excessive thatch from warm-season lawns. Dethatching, if necessary, should precede crabgrass control treatment. (HLA-6604)
· Broadleaf weeds can easily be controlled in cool-season lawns at this time with post-emergent broadleaf herbicides.
· Preemergent crabgrass control chemicals can still be applied to cool- and warm-season turfgrasses. Heed label cautions when using any weed killers near or in the root zone of desirable plantings.
· March is the second-best time of the year to seed cool-season turfgrass; however, fall is the best time to plant. (HLA-6419)
· Cool-season lawns such as bluegrass, fescue, and ryegrass may be fertilized now with the first application of the season. Usually, four applications of fertilizer are required per year, in March, May, October, and November. (HLA-6420)
· Begin mowing cool-season grasses at 1½ to 3½ inches high. (HLA-6420)
Flowers & Vegetables
· Cultivate annual flower and vegetable planting beds to destroy winter weeds.
· Apply mulch to control weeds in beds. Landscape fabric barrier can reduce the amount of mulch but can dry out and prevent water penetration. Thus, organic litter makes the best mulch.
· Avoid excessive walking and working in the garden when foliage and soils are wet.
· Start warm-season vegetable transplants indoors.
· Divide and replant overcrowded, summer and fall blooming perennials. Mow or cut back old liriope and other ornamental grasses before new growth begins.
· Your cool-season vegetables like broccoli, cabbage, carrot, lettuce, onion, peas, spinach, turnips etc. should be planted by the middle of March.
· Watch for cutworms that girdle newly planted vegetables during the first few weeks of establishment. Cabbage looper and cabbageworm insects should be monitored and controlled in the garden. (EPP-7313)
Trees & Shrubs
· Prune spring flowering plants, if needed, immediately following their bloom period.
· Plant evergreen shrubs, balled and burlapped, and bare root trees and shrubs.
· Anthracnose control on sycamore, maple, and oak should begin at bud swell. (EPP-7634).
· Diplodia Pine Tip blight control on pines begins at bud swell.
· Dormant oil can still be applied to control mites, galls, overwintering aphids, etc. (EPP-7306)
· The first generation of Nantucket Pine Tip Moth appears at this time. Begin pesticide applications in late March. (EPP-7306)
· Control Eastern tent caterpillars as soon as the critters appear.
· Continue to plant strawberries, asparagus, and other small fruit crops this month.
· Start your routine fruit tree spray schedule prior to bud break. (EPP-7319).
Remove winter mulch from strawberries in early March. (HLA-6214)
Fruit and Nut
· Don’t spray insecticides during fruit tree bloom or pollination may be affected. Disease sprays can continue according to schedule and label directions. (EPP-7319)
· Fire blight bacterial disease can be controlled at this time. Plant disease-resistant varieties to avoid diseases.
· Continue spray schedules for disease prone fruit and pine trees.
Tree and Shrub
· Proper watering of newly planted trees and shrubs often means the difference between success and replacement.
· Control of powdery mildew disease can be done with early detection and regular treatment. Many new plant cultivars are resistant. (EPP-7617)
· Leaf spot diseases can cause premature death of foliage and reduce plant vigor.
· Warm-season grass lawns can be established beginning late April from sprigs, plugs or sod. (HLA-6419)
· Fertilizer programs can begin for warm-season grasses in April. The following recommendations are to achieve optimum performance and appearance of commonly grown species in Oklahoma.
- Zoysiagrass: 3 lbs N/1,000 sq. ft./year
- Bahiagrass: 3 lbs N/1,000 sq. ft./year
- Buffalograss: 2 - 3 lbs N/1,000 sq. ft./year
- Buffalograss/grama mixes: 3 lbs N/1,000 sq. ft./year
- Bermudagrass: 4-6 lbs N/1,000 sq. ft./year
- Centipedegrass: 2 lbs N/1,000 sq. ft./year
- St. Augustinegrass: 3-6 lbs N/1,000 sq. ft./year
When using quick release forms of fertilizer, use one pound of actual nitrogen per 1,000 sq. ft. per application; water in nitrate fertilizers. (HLA-6420)
· Mowing of warm-season lawns can begin now (HLA-6420). Cutting height for bermudagrass and zoysiagrass should be 1 to 1½ inches high, and buffalograss 1½ to 3 inches high.
· Damage from Spring Dead Spot Disease (SDS) becomes visible in bermudagrass (HLA-7665). Perform practices that promote grass recovery. Do not spray fungicides at this time for SDS control.
· Grub damage can be visible in lawns at this time. Check for the presence of grubs before ever applying any insecticide treatments. Apply appropriate soil insecticide if white grubs are a problem. Water product into soil. (EPP-7306)
· Wait a little longer for it to warm up before planting cucurbit crops and okra.
· Plant vegetable crops in successive plantings to ensure a steady supply of produce rather than harvesting all at once.
· Cover cucurbit crops with a floating row cover to keep out insect pests. Remove during bloom time.
· Watch for cutworm damage and add flea beetle scouting to your list of activities in the vegetable garden.
Garden Planting Guide for Warm-Season Vegetables
Vegetable Time to Plant* Days to Harvest Method of Planting
Bean, Lima April 15-30 90-120 Seed
Beans, Gr. or Wax April 10-30 50-60 Seed
Beans, Pole April 10-30 60-90 Seed
Cantaloupe May 1-20 80-100 Seed or Plants
Cucumber April 10-30 or later 50-70 Seed or Plants
Eggplant April 10-30 80-90 Plants
Okra April 10-30 or later 60-70 Seed
Pepper April 10-30 or later 90-110 Plants
Pumpkin April 10-30 90-120 Seed
Southern Pea May 1-June 10 85-100 Seed
Squash, Summer April 10-30 or later 40-60 Seed or Plants
Squash, Winter May 15-June 15 110-125 Seed or Plants
Sweet Corn Mar. 25-April 30 80-100 Seed
Sweet Potato May 1-June 10 100-120 Plants
Tomato April 10-30 70-90 Plants
Watermelon May 1-20 90-120 Seed
*These dates indicate planting times from southeast to northwest Oklahoma. Specific climate and weather may influence planting dates. For Cool-Season Vegetables, the soil temperature at the depth where the seeds are planted should be at least 40oF.
· Most bedding plants, summer flowering bulbs, and annual flower seeds can be planted after danger of frost. This happens around mid-April in most of Oklahoma. Hold off mulching these crops until spring rains subside and soil temperatures warm up. Warm-season annuals should not be planted until soil temperatures are in the low to mid 60s.
· Harden off transplants outside in partial protection from sun and wind prior to planting.
· Let spring flowering bulb foliage remain as long as possible before removing it.
Landscape - General
· Hummingbirds arrive in Oklahoma in early April. Get your feeders ready using 1-part sugar to 4-parts water. Do not use red food coloring.
· Keep the bird feeder filled during the summer and help control insects at the same time.
· Lace bugs, aphids, spider mites, bagworms, etc. can start popping up in the landscape and garden later this month. Keep a close eye on all plants and use mechanical, cultural, and biological control options first.
· Be alert for both insect pests and predators. Some pests can be hand picked without using a pesticide. Do not spray if predators such as lady beetles are present. Spray only when there are too few predators to be effective.
Trees and Shrubs
· Prune and feed azaleas immediately after blooming.
· Insect Alert: (EPP-7306)
* Bagworms on juniper and arborvitae. (Late May)
* Elm leaf beetles and larvae on elms. (Late May)
* Mimosa webworms on mimosa and honeylocust.
* Lace bugs on sycamore, pyracantha, and azalea.
· Soak new transplants and newly planted trees unless rainfall is abundant.
· Pine needle disease treatments are needed in mid-May.
· Cool-season lawns can be fertilized again. If you did not fertilize cool-season grasses in March and April, do so now.
· Warm-season lawns may be fertilized again in May. (HLA-6420)
· Seeding of warm-season grasses such as bermudagrass, buffalograss, zoysiagrass and centipedegrass is best performed in mid-May through the end of June. The soil temperatures are warm enough for germination and adequate growing season is present to promote winter hardiness.
· Dollar spot disease of lawns can first become visible in mid-May. Make certain fertilizer applications have been adequate before ever applying a fungicide. (EPP-7658)
· Nutsedge plants become visible during this month. Post-emergent treatments are best applied for the first time this month. Make certain warm-season grasses have completed green-up.
· The second application of pre-emergent annual grass herbicides can be applied in late-May or early June, depending upon timing of first application. Check label for details.
· Vegetative establishment of warm-season grasses can continue. (HLA-6419)
· Annual bedding plants can be set out for summer color.
· Plant summer bulbs such as cannas, dahlias, elephant ear, caladiums, and gladiolus.
· Shake a leaf over white paper to look for spider mites. If the tiny specks begin to crawl, mites are present.
· Clean out water garden and prepare for season. Divide and repot water garden plants.
· Begin feeding fish when water temperatures are over 50°F.
Fruits and Vegetables
· Plant watermelon, cantaloupe, cucumber, eggplant, okra, sweet potatoes, etc.
· Fruit spray programs should be faithfully continued during the next several weeks.
Late May is the best time to control borers in the orchard. Check for label recommendations and controls.