A lawn that feels spongy underfoot, where water seems to run off instead of soaking in, may be carrying too much thatch. The UF/IFAS thatch guide says too much water or fertilizer and wrong mowing make grass build a thick, spongy mat called thatch, and that it causes serious problems in Florida lawns. If it has to come out, UF/IFAS points to a vertical mower, with watering afterward. A spongy lawn can wait for a planned visit; it is not a rush job.
Runoff has other causes too, such as compacted soil or water running off high spots, so get the cause confirmed before anyone dethatches. Tampa Landscaping Pros calls back within one business day.
What thick thatch looks like in a Tampa lawn
A spongy mat between the soil and the grass blades
UF/IFAS describes thatch as a thick, spongy mat that the grass itself builds. A spongy feel underfoot alone does not prove thatch. Our crew pulls a small plug to measure the thatch and tells you whether it needs removing.
Water that runs off instead of soaking in
The Washington State University (WSU) Extension home lawn guide links dry spots that stay brown to dry, water-repellent thatch, or to runoff from high spots. That guide is general, not written for Florida, so treat it as a clue to check and not a Tampa diagnosis. If your lawn sheds water after rain or after the sprinklers run, thatch is one cause on the list, and the others are below.
Tampa gets 49.48 inches of rain a year, and 30.24 inches of it, about 61%, falls from June through September, according to NOAA's normals for Tampa International Airport. The question to put to any crew is whether your lawn is soaking that rain in or shedding it.
Grasses with a thatch habit
UF/IFAS describes zoysiagrass, planted as sod or plugs, as slow growing with a tendency to build thatch. For St. Augustinegrass, planted as sod or plugs, UF/IFAS names chinch bugs as the hardest pest, and it lists thatch build-up as one cause of infestations. If you are not sure what grass you have, say so when you call and the crew can look at it on site.
What builds thatch, and what only looks like it
Too much water
UF/IFAS lists too much water among the causes of thatch. Tampa already limits lawn watering. Under the City of Tampa water use restrictions, customers may water lawns once a week, on a day set by the last digit of the house number: 0-1 Monday, 2-3 Tuesday, 4-5 Wednesday, 6-7 Thursday and 8-9 Friday. Watering is allowed only from midnight to 4 a.m. or 8 p.m. to 11:59 p.m. on your day. The regional order runs until March 31, 2027, and it covers homes on private wells too. Breaking the rules can bring fines up to $500 and a mandatory court appearance.
UF/IFAS FAWN says 1/2 to 3/4 inch of water a week is generally the most a home lawn or landscape needs in the hottest part of the year, so treat it as the most to give, not a weekly target. It also says that after 0.3 inch of rain in 24 hours, or 1 inch in 3 days, irrigation may not be needed that day. Florida law requires every automatic lawn sprinkler system to have working technology that stops it when there is enough moisture, so a timer that runs through a storm is worth a look.
Too much fertilizer
In Tampa, lawn and landscape fertilizer with nitrogen or phosphorus may not be applied from June 1 to September 30. There is also no fertilizer within 10 feet of water. UF/IFAS links too much nitrogen to chinch bugs, and too much fertilizer to thatch. Anyone who applies commercial fertilizer to a Florida yard for pay must hold the state limited urban landscape fertilizer certification, so ask to see it.
Wrong mowing
UF/IFAS names wrong mowing as a thatch cause, and mowing too short as a chinch bug cause. UF/IFAS also says never to cut more than a third of the blade at once. For bahiagrass, UF/IFAS gives a mowing height of 3 to 4 inches. Ask the crew what height suits your grass before the next cut.
Compacted soil that looks like thatch
UF/IFAS says compacted soil usually comes from heavy foot or vehicle traffic and is common around newly built homes. It also says that if you struggle to push a tool more than a few inches into the soil, the root zone is likely compacted, which leads to shallow roots and poor drainage. In Tampa and Hillsborough County, UF/IFAS Extension says urban development often leaves compacted, nutrient-poor sandy soil. North and Central Florida soils are typically very sandy and do not hold water or nutrients well. Our page on compacted lawn soil covers that test and its fixes.
Chinch bugs living in the thatch
UF/IFAS calls thatch a perfect habitat for chinch bugs. Chinch bug damage shows as yellow to brown patches, and heavily infested St. Augustinegrass turns yellow first, then quickly dark brown. UF/IFAS advises non-chemical steps first, such as less thatch and less fertilizer, and treating only with a suitable pesticide while rotating products each season. If you see brown patches as well as a spongy lawn, read about chinch bug damage in St. Augustine lawns.
Cost
What to do about a spongy lawn, and what it costs
Checks you can do yourself
- Walk the lawn and note where it feels spongy, and whether those spots also shed water.
- Push a tool into the soil. If it will not go in more than a few inches, suspect compaction before thatch.
- Check which day your sprinkler timer runs against the Tampa day for your house number, and that it only runs in the allowed windows.
- Look at the rain sensor on the system. Bob Vila's 2024 sprinkler guide lists $10 to $100 for one, as a national range.
- Write down the date of the last fertilizer, and the mowing height you use.
What to leave alone
- Do not water extra to get water to soak in. Outside your day and the allowed hours, Tampa can fine you.
- Do not feed the lawn between June 1 and September 30 to make it look better. The ban covers nitrogen and phosphorus.
- Do not blow or rake the thatch and clippings into the street. Grass clippings, fertilizer and yard waste may not be blown or placed into the street in Tampa.
- Do not spray anything on a guess. Anyone applying pesticide to lawns for hire must hold their own FDACS certification or work under a licensed Lawn and Ornamental operator. Ask who will apply any weed or pest treatment and which state licence they hold.
The fix UF/IFAS describes
UF/IFAS says that if thatch must be removed, use a vertical mower and water afterward. It names sand topdressing as the best biological control and core aeration as a way to help prevent thatch. Its general lawn disease advice also lists aerating to cut compaction. Ask the crew what will change in the watering, fertilizing and mowing so the mat does not build again. Ask for a written start date and finish date with the quote. Watering after the work still falls on your Tampa day, because hand watering of lawns follows the designated day too.
When the lawn is too far gone to fix
UF/IFAS Extension Hillsborough County says to replace a lawn when 30% or more of it is weeds, bare spots or damage. Never lay sod over existing weeds and grass; remove or kill them first. UF/IFAS says to water new sod lightly but often for the first 2 to 3 weeks and to wait 3 to 4 weeks before the first mow. In Tampa, new sod still may not be watered between 4 a.m. and 8 p.m.; the city points to the UF/IFAS 30-day establishment schedule, then normal watering days apply. These are national ranges from 2026 cost guides for the replacement route:
| Item | National range |
|---|---|
| Sod installed, average | $1.65 per square foot |
| St. Augustine sod installed | $0.98 to $1.79 per square foot |
| Removing weeds and old grass, disposal included | $0.88 to $1.84 per square foot |
| Professional sod install on a 1,000-square-foot yard, old grass removal not included | $1,000 to $2,200 |
| Lawn soil test | $35 to $100 |
What moves the price when a lawn is replaced: how many square feet are involved, whether old grass has to come out, how much tilling and grading the ground needs, and the grass you choose. Ask for a written, itemized price after the crew walks your Tampa yard and measures it. See our guide to Tampa landscaping cost for the wider picture. Tampa Landscaping Pros pulls the City permit when the job needs one.
Questions about thick thatch in a lawn
Should I water more to soak a spongy Tampa lawn?
No. Tampa lawns may be watered once a week, on the day set by your house number, and only from midnight to 4 a.m. or 8 p.m. to 11:59 p.m. UF/IFAS lists too much water as a thatch cause, and breaking the watering rules can bring fines up to $500.
Why is my lawn spongy and why does water run off?
Thatch is one possible reason, and WSU Extension links dry spots to water-repellent thatch or runoff from high spots. If water runs off, compacted soil is another possible cause: UF/IFAS says a tool that will not go more than a few inches into the soil points to it, and compaction leads to poor drainage.
Do I need dethatching?
Our crew pulls a small plug to measure the thatch and tells you whether it needs removing. If it does, UF/IFAS says to use a vertical mower and to water afterward.
Can I fertilize a spongy lawn in the summer?
Not with nitrogen or phosphorus in Tampa. Those products may not be applied from June 1 to September 30, and UF/IFAS lists too much fertilizer as a thatch cause.
Does thatch bring chinch bugs?
UF/IFAS calls thatch a perfect habitat for chinch bugs and also lists thatch build-up as a cause. It advises less thatch and less fertilizer before any pesticide.
How much does dethatching cost in Tampa?
Ask for a written, itemized price after the crew walks your Tampa yard and measures it. If the lawn has to be replaced instead, the national sod figures above give the range.
Cost
Get a written price for a spongy lawn
Call us or use the form. We call you back within one business day. The crew comes out and measures, and Tampa Landscaping Pros gives you a written price before any work starts.