Analysis Lawn grass naturally goes to seed. In cool-season grass lawns, seed head production is prompted by days in excess of 12 hours long, which occurs around the middle of May. Seed head production is heaviest when daytime temperatures are between 65° and 75°F, the weather is dry and the soil low in nitrogen. Some grass varieties produce more seed heads than others. Seed heads are most likely to be perennial ryegrass, Kentucky bluegrass, or tall fescue. Rough bluegrass and annual bluegrass, two common lawn weeds, produce seed heads in the spring. Warm-season grasses may also produce seed heads, but do so in the summer, and their seed heads are not difficult to mow. Unless they are allowed to ripen for about 4 months, seeds will not sprout, either in the lawn or in a mulch or compost made from clippings. Seed head production weakens grass by diverting energy to making seed.
One of the most common lawn care questions we receive each year is about a strange wheat like weed growing in lawns. Good news, it’s not a weed, but rather a seed head! A seed head is a normal part of the grass life cycle that occurs each spring in our area. All grasses produce seed heads at some point throughout the growing season, it’s the plants way to reproduce and ensure survival.
Problem Info Seed heads appear in the lawn in the spring. They are tough and hard to mow, and the lawn may appear white after mowing because of the shredded stems. Lawn grass naturally goes to seed. Seed heads are most likely to be perennial ryegrass, Kentucky bluegrass, or tall fescue. In cool-season grass lawns, seed head production is prompted by days in excess of 12 hours long, which occurs around the middle of May. Warm-season grasses may also produce seed heads, but do so in the summer, and their seed heads are not difficult to mow.
Seed head production requires energy from the grass plant, potentially causing a temporary lightening in color. The turf looks stemmy due to seed stalks, and short-term thinning of the turf stand. All these temporary issues eventually correct themselves as the plants grow and enter the next step in the grass life cycle. The best way to ensure a speedy recovery is by enhancing growth through regular watering and fertilization.
Solution Advice If grass is taller than usual, mow it at regular intervals, slowly lowering the mowing height until it is about 3 inches high. Do not mow lower in an attempt to halt seed head production, but you may mow more frequently to maintain the appearance of the lawn. Use a sharp mower to avoid shredding the stems. Reduce seed head production next year by fertilizing and watering regularly from early May through June. Nitrogen fertilizer and ample water encourage vegetative growth instead of seed head production.
Control: Mulch your garden to prevent purslane or use a preemergence herbicide in the spring. Pull plants by hand or spot-treat with a nonselective postemergence herbicide.
Type: Broadleaf perennial
Where It Grows: Sunny or partly shaded lawn, landscape, or garden areas
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Size: To 6 inches tall and 2 feet wide
Size: To 8 inches tall and 2 feet wide
Size: 4 inches tall, several feet wide
Type: Annual grass relative