Lawn Thatching/Dethatching

What is thatch? Below the green blades of grass and above the soil surface, is a layer of mixed debris of dead grass, grass clippings, surface roots, blades of grass that grow horizontally instead of vertically (lazy grass) and then leaves, sticks, tree nuts and half eaten sandwiches. Like a carpet or rug debris can settle into it and needs to be cleaned out.

Having a thin thatch layer helps hold in moisture in the soil, keeping the lawn from quickly drying out in the summer and allows water, air, and fertilizer to pass through into the soil. The thatch does decompose and help feed healthy microbes in the soil making good soil to grow better grass. Less watering and fertilizer can be used since results will be seen quickly.

Too much thatch slows down water, fertilizer and air passing through to the soil. Water will run off the grass to the surrounding yard carrying fertilizer that doesn’t work into the soil, which more fertilizer is needed to see results which are slow to see. Once watered the thatch becomes a sponge, leaving the lawn to feel always wet and rot the grass blades. Grass roots being to grow towards the thatch to get water, air and fertilizer that gets trapped in it. Shallow roots dry out during the summer faster, leading to the lawn drying out quickly needing more water.

Lawn disease and fungus happens more often in thick thatch layers. Creating discolored grass color, spots on the grass blades, dead grass patches or dead thinning grass throughout the lawn. Insects like to populate in and under the thatch, which spread out the yard. Some insect activity is fine and normal, but having ant hills through the yard then are dug out by insect eating animals, that are always happy to be surprised (skunks for example).

Signs of thatch buildup? Look at the grass, can you see the soil below? Do the blades of grass standup or do some grow along the ground and look like a fresh game of pickup sticks?  Walk on the grass does it feel soft and squishy? Take a knee and drag your fingers through the grass like a claw, do you have any debris or pale dead grass come out or random long blades of grass like a bad haircut? Or do you have signs of lawn disease, fungus or insect problems? If you see any of this, your lawn needs to be thatched.

When to thatch? If you have an insect problem or a fungus/disease issue, maybe dead patches or dead thinning throughout the lawn. Remove the dead grass before treating. (If you don’t have a thatch layer, just fungus/disease or insect problem, no need to thatch). Problems like these happen throughout the growing season, treat as needed.

Normally thatching is done in the spring or fall. Reasons as to why vary depending on the region you live in and grass type. Spring Thatching lifts up grass that has laid down during the colder dormant months or snow and ice on top of the grass blades, also get any leaves, sticks, tree nuts and other debris that blew on to the lawn out and not damage mower blades. If you use a dethatcher your lawn will have stripes for a nice clean look. Fall Thatching lifts up any grass blades that grew horizontally during the growing season, remove any clippings that didn’t break down and get leaves out that can prevent grass from growing and making a small bald spot in the lawn. Also, using a dethatcher will stripe your lawn, making your lawn look good until a blanket of snow, ice or heavy rain flattens out the grass during winter. These were the reasons I heard growing up, may vary by region and grass type.

Thatching Equipment. Some types of thatching equipment ranging from inexpensive up to expensive. Starting with hand rakes, different shapes, sizes and build material. Great for small areas and/or hard to reach spaces. Steady pressure until your arms get tired. You can pick up the debris as you go.

Purpose built thatching rakes are another hand tool with thin vertical blades that you push and pull through the lawn. Faster than a hand rake… (a little), same as hand rakes when your arms get tired you slow down and still have to pick up the debris as you go.

Spring thatching mower blade, an aftermarket mower blade with one spring tine at each end of the blade. Usually for 21-inch rotary mowers. Ground pressure is set by the mower deck height. Can help pick up debris into the bag of the mower. I haven’t seen these blades in stores around me for anything other than a 21-inch mower. Good for small to medium yards or if you have tight gates or pathways to get to your lawn.

 Small cored electric dethatcher/verticutter (ex. sun joe) non-commercial machine depending on how many extension cords you have you could cover a lot of ground with these machines. Like the more common gas-powered power rake dethatchers, also you can switch drums from a spring tine drum or a verticutter drum easily, and are cheaper to own and easier to store in sheds or garages. Quicker and more towards a professional level of results. You have to pick up debris after.

 Tine rake dethatcher attachments for lawn mowers, can either be front mounted or tow behind. Can be used on small to large yards, you do need a self-propelled/ride-on mower, tractor or UTV/ATV. Spring tines are pushed or dragged through the lawn. Great for helping maintain a healthy thatch layer, multiple and alternating passes over the lawn would need to be done to remove as much thatch as a power rake dethatcher. Can pick up the debris as you go, if it’s a front mounted rake.

Gas powered dethatcher/power rake/lawn comber most noticeable and common of all thatching equipment. Gas powered, unlike the sun joe cored electric unit. Various widths sold and even a tow behind extra wide units, these machines can have spring tine drums, flail blade drum or a verticutter (fixed blade) drum. Size and drum style vary depending on availability in your area. Good on any size yard, can easily adjust drum height to lightly rake through the grass or go into the surface of the topsoil, just be careful these machines can remove most grass or weak rooted grass leaving you with almost no lawn. Depending on the health and look of your lawn could be what you need to start getting a better lawn. You after to pick up debris after.

Another type of equipment are rotary brooms. Sizes vary from narrow trimmer attachments or mounts, walk behind models, machine mounted and tow behind models. Stiff bristles pulled out debris out. Height adjustment can be done of ground pressure, smaller units may come with wheel kits depending on manufacturer. Size of the yard varies by the size of the broom. These can also be used for other tasks besides thatching throughout the year.

How to Thatch:  Mow your lawn low, at least two and a half inches (2.5”), make it easier to get the thatch and debris out, no matter which tools or equipment you use and bag the clippings. Rake out any tight areas that you can’t reach with bigger equipment, then thatch the lawn. Next depends on how much thatch is pulled out of the lawn which determines if you (need/or should) thatch again in a different direction. One pass with the equipment may have been all you needed to do on the other hand a lot of thatch is now on top of the lawn and you can’t go over the lawn until the thatch is picked up off the lawn to see if you need to remove more thatch. Picking up the thatch, can be done by raking into piles and moving the piles, use your lawnmower to bag the thatch or use a lawn vacuum. After all of that, one more time over the lawn with either your lawnmower with the bag on or a lawn vacuum to pickup any leftover thatch and trim up any long grass that was hiding in the lawn.