Growing a Beautiful Lawn on a Clay Soil
For some people, having a thick, green lawn is something that just happens. This is few and far between as most people are going to have to do a little bit of work to get the same results. Seriously, we have some customers that their grass just grows, and grows, and grows, all summer long , with minimal weeds. Doesn’t matter if it has been a dry summer with minimal rain or wet and mild. It just grows like a sod farm. If this is you, congratulations, you have officially made me jealous. This is like hitting the jackpot in terms of turf. How does this happen though? Well it all starts with the…
I’ll try and keep this as straight forward as possible when it comes to soil textures as that could be a completely different topic with tons of technical mumbo-jumbo. Soils come in all different shapes and sizes but there are 3 main textures: Sand, Silt, and Clay. There are actually more types but I’ll be using Sand and Clay in my examples as these are on the opposite ends of the spectrum. I should also note that your soil will be a combination of these, it’s pretty rare to have a 100% clay, sand or silt soil.
Classified as having very small particles, clay soils have a very high CEC (Cation Exchange Capacity). This simply means they have a better capacity to hold nutrients. They also hold water extremely well, suffer from being easily compacted and typically take longer to warm up in spring time. When these are dry they feel like concrete, they are extremely hard and will typically crack.
Classified as having the largest particles of any soil type, Sandy soils are sometimes called hungry as they will typically require greater amounts of nutrients and H20 due to leaching and runoff. Leaching simply means they don’t hold nutrients well, when it rains those nutrients are more prone to washing through the soil. Compared to clay, these soils are a dream to actually work with as they are much lighter.
How do you know what type of soil you have? Chances are if you have done ANY digging, you will know if you have clay. A heavy % clay soil is AWEFUL to plant in. Absolutely horrible. If it’s too dry you’ll feel like your trying to break through concrete. If it’s too wet, it will just create a sticky mess, best to wait it out and let it dry a bit. If your still not sure if you have a heavy clay soil, do the ribbon test. Basically, take a moistened bit of soil and rub it between your thumb and pointer. (kinda like your doing a the money gesture) The idea is to create a ribbon. The longer the ribbon, the more clay you have. Anything over 2″ would be considered clayey.
The good news
There is some light at the end of the tunnel. If your willing to put the work in, clay soils can actually be an awesome soil to grow plants and grass in. The biggest benefit to having clay is its capacity to hold and amazing amount of nutrients and water. While you can use many of these tips for your landscape and garden, the rest of this article will be aimed toward the turf.
Organic matter, Mother Earths great equalizer
Unless you plan to completely overhaul your soil/yard, you need to start thinking about how you can incorporate more organic matter into your soil. Organic matter can be compost, lawn clippings, leaves, or even organic fertilizer. Simply put, its almost anything carbon based the will biotically deteriorate/degrade over time. Biotically meaning the soil organisms will break it down. Maybe not so simple I guess. Basically they will amend your soil over time and act as a medium to increase your drainage while keeping its water and nutrient hold capacity.
Amending an EXISTING lawn
Here are a few things you can do for your existing turf to increase its organic matter:
Leave your grass clippings
I recommend that EVERYONE does this, no matter what kind of soil you have
Mulch your leaves
Instead of bagging you leaves, mulch em’. Every week during the fall season, mow the lawn and mulch those leaves. Sometimes you may need to mow a couple times throughout the week if theres some heavy tree cover. Please note there are times when there’s just too many leaves and you will HAVE to bag them as to not suffocate your lawn.
Use an Organic Fertilizer
I am certainly not a 100% organic or go home kind of guy, but they definitely can help with a heavy soil. They will promote activity of those soil organisms and increase the amount of organic matter in your soil just like leaves or grass clippings. Remember, an Organic Fertilizer could be anything from Bone Meal to Milorganite. (This is what we use) It should also be noted that an Organic Fertilizer will be lower in actual nutrients and slower releasing meaning you’ll likely have to put in on multiple times throughout the growing season.
Topdress your lawn with a nice compost/topsoil mix
A VERY good way to start amending your soil is to add a very thin layer (around ¼”) of compost or 50/50 mix on top of your lawn. There are actual machines that can do this, but if your lawn is smaller, grab a wheelbarrow and start spreading! Around here we have a supplier that has a very very nice 50% topsoil, 50% compost mix that works great.
Aerate your lawn
I love aeration. The idea behind amending the soil is to get those amendments deeper into rootzone of the soil over time. Just doing the things I listed above will absolutely help, but adding aeration will drastically increase the depth and time it takes for those amendments to get into the rootzone. It will also help relieve compaction that clay has such a hard time with. Aeration does a lot for your lawn, read more about it HERE.
Putting it all together
Here is what I would recommend doing for someone willing to put in some work to amend their existing turf. It does take a long time to completely amend your soil. This is not a one time thing but a complete change of routine for your lawn. Doing this year after year will help your clay soil drastically and give you a much stronger and healthier lawn.
- Start using an organic fertilizer throughout the season. We use Milorganite and apply it 5 times throughout the year.
- During the summer, start mowing tall (it will help with keeping your soil cooler along with many other benefits) and keep the lawn clippings on the lawn.
- Make sure you water your lawn and keep it from drying out. A bone dry clay soil is going to be rock hard and not allow water/nutrients to get into the rootzone
- When the temperature start to get cooler but before the leaves start dropping, start by aerating your lawn, followed by an over-seeding of appropriate seed type and apply an organic fertilizer. Afterwords spread a thin layer (¼”) of compost or 50/50 mix on top of your lawn.
- During the fall start mulching your leaves. Remember, you may need to bag some of your leaves to prevent your lawn from becoming suffocated. If your new seed is starting to pop up, be extra careful not to damage it.
Remember, this is something you need to be doing EVERY year. You simply CANNOT expect to do this one year and have an outstanding lawn the next. Yes, you will start to see improvements during that first year but that’s not what we are after. What we are after is a long term change in the actual soil and that takes time. Follow these steps and after a couple years your WILL have a much healthier, thicker, greener lawn.
One thing I should probably go through is what you should absolutely not be doing:
- Add sand to clay
But wait, wouldn’t adding the opposite of clay create an awesome soil? No, It won’t. You will however create a VERY nice concrete like soil. Seriously, don’t do it.
- Smother your lawn with leaves
Mulching them is great. Mulching too many at once is not. If you have a thick layer of Bur Oak leaves that’s 6″ deep. Don’t even try to mulch them. Instead you should be mulching it more often as to not allow for them to pile up. Or bag some of them. Trees such as the Silver Maple typically have leaves that can, quite literally, be turned into dust. Even large amounts are great for mulching.
- Add wood chips to the lawn
Not sure why anyone would actually try this, but don’t. Wood chips actually pull nitrogen out of the surrounding soil when they decompose. Ever notice that grass grown on top of an old tree that was chipped out will start nice and green but quickly fade to lime green? It’s the wood chips underneath that grass.
- Allow your clay soil to dry out
Once they become dry they will be extremely hard. This means water and nutrients will literally not percolate down into the soil. Keep them moist throughout the heat and you won’t have any issues.
- Mow your lawn short
The higher you cut your grass, the more shade it will provide to the soil. That means it will stay cooler and require less water. Remember dry soil= rock hard soil.