Q: I’m seeing crabgrass in my lawn again this year. I’ve tried several crabgrass killers in the past, but nothing seems to work. Help! Also, why does crabgrass always seem to grow better in hot weather than my grass?

• Robert in Boardman

A: Crabgrass is a bane for many homeowners. This annual grass is originally from Eurasia but is now found worldwide.

There are two types of crabgrass common in Ohio, large crabgrass and smooth crabgrass. Both types are spread by seed and crabgrass is a prolific seed producer. It can produce up to 100,000 seeds per plant. No wonder it’s found everywhere.

You may not need herbicides to manage crabgrass. A healthy lawn is an effective way to control crabgrass and other lawn weeds. Help keep your lawn healthy by mowing high, a minimum of 2.5 inches. Cutting at 3 inches and just above this time of year will really help your own lawn outcompete the crabgrass. A higher cut will help the lawn grow stronger and denser, which discourages weeds.

Don’t fertilize the lawn in summer. Summer fertilizing feeds the crabgrass and other lawn weeds more than the turf grass. The best time to fertilize a lawn is in the fall. When you water the lawn, water it deeply and avoid frequent, light watering.

As for herbicide controls, there are two types available, a pre-emergent type and post-emergent. Both types require correct timing to be effective.

A pre-emergent is used in the spring and must be applied before the seeds begin to germinate. It has no effect if applied after germination, and if applied too early, the chemical will not last for the entire season.

Crabgrass germination starts when the top part of the soil warms to constant 55 to 60 degrees. How can you know when the soil has reached this temperature range? Watch the blooms on forsythia — they begin to fade when the soil reaches these temperatures. No forsythia nearby? Michigan State has a website to help plan your application at http://gddtracker.msu.edu.

Be aware that a crabgrass pre-emergent also prevents turfgrass seeds from developing. Do not reseed your lawn when using a pre-emergent!

Post-emergent herbicides work on plants. Crabgrass post-emergents work best when the plants are small. Usually by mid-July, the crabgrass is too large for effective control. Post-emergent control is not considered as effective as pre-emergent. If you use either one, read and follow the directions on the product label.

You are right, Robert, crabgrass does outcompete turf grass in the hot part of summer. Most turf grasses in Ohio lawns are cool seasons grasses. They grow best when the temperature range is 60 to 75 degrees. Crabgrass is a warm season plant, growing best when temperatures are 80 to 90 degrees. The reason has to do with the differences in how the plants photosynthesize.

Your turf grass should recover and crabgrass growth will slow down when cooler temperatures arrive. The first freeze will kill the crabgrass.

It’s hard to have a completely crabgrass-free lawn. It’s all right to have some crabgrass in the lawn. When you see it growing, just pull it. Congratulations — you have then removed 100,000 crabgrass seeds from your lawn.

For more information on crabgrass, visit http://go.osu.edu/crabgrass.

Sprague is an Ohio State University Mahoning County Extension Master Gardener volunteer. Call Sprague and others in the clinic at 330-533-5538 to submit your questions. Regular clinic hours are 10 a.m. to noon Thursdays or visit go.osu. edu/virtualclinic.