With the gentle rain and cool temperatures, most lawns will need to be mowed every five to seven days.

However, one plant popping up this year in great quantities needs to be mowed almost daily. Orchardgrass is a long-lived perennial bunch grass that has become a weed in many home lawns. Grown mostly for feeding cattle, it does quite well in the urban environment. If you have spindly open clumps of sod that seem to grow overnight, here is what you need to know about orchardgrass.

Orchardgrass is a cool-season grass that begins to grow in early March. It grows best at a combination of 72 degrees during the day and 54 degrees at night. Flowering date depends on the variety, temperature and length of day, but it usually flowers and sets seed in May. Orchardgrass is less tolerant of heat and drought than tall fescue. It greatly slows growth when temperatures reach 82 degrees. It is tolerant of shade and can thrive in various soil conditions.

Orchardgrass is a problem in home lawns because of its coarse texture and rapid growth rate. It grows above the rest of the lawn and is unsightly. It is introduced into home lawns by overseeding, a practice that is highly recommended for our area. Unfortunately, many of the cheaper seed packages are contaminated with orchardgrass seed. It appears on the label as “other crop.” “Other crop” refers to any species that is intentionally grown for some purpose.

That would include turfgrasses (those species other than the one you are buying) and forage grasses, which are both perennial grasses that usually cannot be selectively controlled in a lawn. Orchardgrass falls into this category. Seed labels are required by law to show the percentage (by weight) of “other crop” in the bag. However, unless a species constitutes 5 percent or more, the label doesn’t have to list each species by name.

How much “other crop” is too much? That is a difficult question to answer, but the tolerance is very low. It depends on what the “other crop” actually is and the quality expectations of the buyer. In practice, “other crop” may refer to something relatively harmless, like a small amount of perennial ryegrass in a bag of tall fescue, or it may refer to something bad, like rough bluegrass or orchardgrass. The homeowner really has no easy way of knowing what the “other crop” is. If it is something bad, less than half of 1 percent can ruin a bag of seed. For example, if a bag of tall fescue seed contained 0.5 percent percent orchardgrass, the buyer would end up “planting” 12 to 16 orchardgrass seeds per square foot.

And once planted, there is nothing a homeowner can do. There are no herbicides labeled for selective control of orchardgrass. It will naturally have to die out, or be choked out with an aggressive overseeding program with clean seed. Until then, homeowners are left with mowing and patiently waiting for the invaders to slowly disappear.