Skip Richter, based in Houston, is a popular speaker for garden clubs, Master Gardener programs, and other gardening events across Texas. He has...Full Bio


Soil remediation is still a priority in 2019

My apologies up front to longtime Lemmonheads who probably know all this. Especially those who have been consistent with compost top-dressing and soil remediation since Hurricane Harvey.

For the past two months, I’ve been hearing from many people with soil conditions so bad from Harvey and the rains of late 2018 that they don’t know what’s going on or where to begin in lawn care. Sadly, some have just recently returned to their homes and need serious soil remediation.

If you fall into those categories, or if your grass is not responding to the first stages of my fertilization schedule, I’m going to dive deep here into everything about soil remediation.

The information that follows is for the true do-it-yourselfer. If that’s not you, two companies I endorse that will do it for you are listed at the bottom of the page.

First, when was the last time you core-aerated and compost top-dressed your lawn?

  • If it’s never been done, try to have it done twice a year for the next 2-3 years.
  • If you’re dealing with super hardpan or clay soil, do it twice a year for the next 2-3 years as well.
  • If it’s only been done once in the past 3-5 years, try to get two more in over the next 18 months.
  • If your lawn is healthy, do it once every 2-3 years for maintenance.
  • If things are fairly decent and you just want to do once a year, consistency is good theme.

And let’s clarify when to do it. Spring is the optimum time, but an aeration and soil amendment can be done at any time of the year along the Gulf Coast.

During April and May, homeowners’ thoughts always turn to the quality of their lawns. A beautiful lawn is measured in terms of color, density and uniformity. Soil conditions, fertilization, and watering are the factors that affect lawn quality. And the condition of your lawn's soil and your fertilization schedule have the greatest impact. If you’re a GardenLine regular, you know how well my Lawn Fertilization Schedule works with decent soil.

But, if you're following my schedule, and the lawn hasn't responded, that’s an indicator of really bad soil. Your grass may be just unable to take up the nutrients provided in the spring fertilization. Is the soil beneath your grass hard and lumpy? Does water run off after the grass has been irrigated? Does it always seem "thirsty," wilting by the next day? Is it not as green as it should be? Is your lawn full of weeds? If so, your lawn is a prime candidate for core aeration and compost top-dressing.

So, what is core aeration?

It’s a process performed with a special machine that pulls out plugs of soil. This opens up the soil structure, allowing air, water and fertilizer to penetrate more deeply, reaching the grass roots. Core aeration also makes the soil more friable or crumbly, a condition allowing roots to spread more easily, as opposed to staying stagnant. Friable soil also helps earthworms, nature's core aerators, to more easily tunnel through the lawn, moving more nutrients and water. Plus, the castings they leave behind are excellent fertilizers.

I am a big proponent of compost top-dressing after a core aeration. However, compost can seem costly to some people, and spreading it around, although extremely beneficial to the soil, can be onerous and time-consuming. So I also recommend just about any soil amendment - from gypsum and expanded shale, to humates, dried molasses and products like Azomite that bring trace minerals and micro nutrients to the soil. They’re sort of like a B12 shot to humans. And almost all soil amendments can be put out with broadcast spreaders.

When it comes to compost, I always prefer to use finely screened leaf mold. Most animal manure-based composts are not as spreadable, especially for a DIYer. Companies that professionally spread compost use tools not available for rent at retail – yet. So, if you are going to do it yourself, you’ll need to distribute tiny piles of compost with a leaf rake.

Whether you perform the core aeration yourself or hire a company for the job, be sure the machine being used has tines that are of appropriate length and spacing. Soil scientists and turfgrass experts recommend tines that are a minimum of 4 inches long, spaced at 2-3 inches. If the tines are farther apart, multiple passes over the area will be required. If you do it yourself, make sure to mark off sprinkler heads. Running over them will damage both the heads and the machine's tines.

The cores extracted can be left to degrade naturally, or be broken up a day or two later by simply mowing over them. Or, you can rake them up to toss into a compost pile. Or just throw them away.

Finally, be sure to water the lawn thoroughly after the process, to help move both soil and amendments into the holes.

You may be asking why you can’t just poke holes in the lawn using golf shoes or those spike attachments you see advertised in Sky Mall magazines. Or, for that matter, with a pitch fork. Well, just sticking sharp objects into the soil doesn’t remove a core. That only pushes soil aside to create a hole and actually compacts the soil even more. So wearing spikes on your shoes while mowing or walking on the grass is not a good technique. Bermuda grass can be walked on with golfer shoe-type spikes, but it’s not as beneficial as a genuine core aeration. And if you have a lumpy yard, just going over it with a heavy roller also only further compacts the soil.

You can rent core aeration machines from retail stores. You might consider getting a couple of neighbors to go in on one with you, because …

  1. It’s a big, unwieldy piece of equipment that takes two people to load and unload from a truck.
  2. Splitting the rental fees among 2-5 people is super cost-effective.

When I lived in Cypress, Neighbor Steve and I would split the cost with two others, and it cost us about $20 each. You can aerate an area in about a quarter of the time it takes to mow it. So, theoretically, you could probably do about eight lawns in eight hours.

By the way, a core aeration and top-dressing or soil amendment really has no effect on my fertilization schedules, whenever you do it. In a perfect world, I would wait a week or two before doing a fertilization. But if you fertilized and did an aeration right after, it’s fine. Once you do a soil remediation and pick back up on any fertilization schedule, your lawn will show results in as few as 30 days.

As I mentioned above, Green Pro and Year Round Lawn Care are two companies I endorse that provide aeration and compost top-dressing services if you'd prefer not to do it yourself.

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