March Gardening Tips
Oklahoma Cooperative Extension Service, Division of Agricultural Sciences and Natural Resources
Department of Horticulture & Landscape Architecture, Oklahoma State University
David Hillock, Consumer Horticulturist
Lawn and Turf
- Remove excessive thatch from warm-season lawns. Dethatching, if necessary, should precede crabgrass control treatment. (HLA-6604)
- 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 and 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.
- Prune roses just before growth starts and begin a regular disease spray program as the foliage appears on susceptible varieties. (HLA-6403 & EPP-7607)
- 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 and 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).
Cutting Back Ornamental Grasses
Ornamental grasses should be cut back in late winter before new growth emerges. It can also be done in fall, but the seed heads provide nice winter interest, and some birds will also feed on the seed. To make the job easier, tie up the stalks with string. Depending on the size and density of the grass, the following tools might be used: house scissors, shears or hand pruners, and electric hedge trimmers (for very large clumps). For smaller grasses, trim to about 2 to 3 inches from the ground; for larger grasses cut 6 to 8 inches from the ground. One exception is with the species Nassella (Stipa) tenuissima, Mexican Feather Grass, it does not respond well to heavy pruning and prefers to only be cut back by 1/3 to 1/2 its height.