Which grass do you have?
Bermuda is fine-bladed, spreads aggressively, loves full sun and hates shade. St. Augustine is wide-bladed and coarse, the most shade-tolerant of the three, and the most prone to fungus and chinch bugs. Zoysia is in between: dense, soft, slower-growing, decent in part shade. Most of what follows applies to all three; where it differs we say so.
February 15 – March 15: spring pre-emergent
The most important date on the calendar. A pre-emergent herbicide applied before soil temperatures reach 55° stops crabgrass, grassburs and other summer weeds from germinating. Apply when the redbuds bloom, water it in with half an inch, and do not aerate or dethatch afterward (it breaks the barrier). Skip it on a lawn you plan to seed or sod within a few months.
April: first feeding
Fertilize after the lawn has been mowed twice and is fully green, usually mid-April. Feeding a dormant lawn in March feeds the weeds. Use a slow-release fertilizer with a 3-1-2 or 4-1-2 ratio (something like 21-7-14 or 19-5-9); an organic like corn gluten meal works too and doubles as a mild pre-emergent. If you saw grubs last year, this is also the month to apply a preventative grub product.
May – August: mow high, water deep
Mowing heights: St. Augustine 3–3½ inches, Zoysia 2 inches, Bermuda 1–1½ inches. Never remove more than a third of the blade at a time. Water about an inch a week in two deep sessions before sunrise (see the watering guide). A light feeding in early June is fine; nothing in July and August. Watch for chinch bugs in St. Augustine (dry patches next to concrete that do not green up), grubs in July (turf lifts like carpet), and gray leaf spot after wet weeks.
September 1 – 15: fall pre-emergent and the big feeding
A second pre-emergent in early September stops henbit, chickweed, dandelions and poa annua — the weeds that carpet lawns in February. Fertilize at the same time; the September feeding builds the root reserves the lawn uses to green up next spring. Finish all feeding by October 1 so growth hardens off before frost.
October – November: brown patch season
Cool nights and warm days bring brown patch to St. Augustine and Zoysia: circular yellow-to-brown patches that spread outward. Cut back on watering, water only in the early morning, and treat with a lawn fungicide at the first sign. Mow leaves into the lawn rather than raking — they are free fertilizer — but do not let a thick mat sit on the grass.
December – February: leave it alone
Dormant, tan grass is healthy grass. Water once every two or three weeks if there is no rain, more before a hard freeze. Do not fertilize, do not scalp until late February or early March, and keep foot traffic off frozen turf.
Thin lawn? Fix the cause first
Grass thins for three reasons: shade (St. Augustine needs 4–5 hours of sun, Bermuda needs 8), compaction (aerate in late spring), and disease or insects. Sod patches and fertilizer will not fix a shade problem — a shade-tolerant groundcover from the Plant Finder will.
Written by the Nursery Professionals at Landscape Source Nursery, 167 Ole West Lane, Rockwall. Questions? Call (469) 698-0037 or send us a note.