Improve Heavy Clay Soil

Turn your clay soil into the best garden soil you have ever used.

0:00 Start
1:40 clay soil myths
5:20 Measuring the amount of clay
6:40 Solving a clay problem

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Improve Heavy Clay Soil
Myths about clay soil, using gypsum to break up clay, adding organic matter - which method is best?

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[ronallens]

U don't have to guess if have clay soil when you try to dig in it is when the shovel bends and you spend an hour using a pick to dig a small hole

[nicholasbenedetto]

I live in Chicago. I had 18 inches of clay topsoil, with yellow clay underneath. We had the sewer drainpipe collapse. They dug a trench 30 ft long x2 feet wide. So, I had a lot of that yellow clay to deal with.
I used gypsum. Let it sit and percolate for 3 months. Had to pulverize it with a sledgehammer. Then I added sawdust, sand and compost, all in equal amounts. Used it in raised beds, adding 3" of compost and 1/2"sand, and 1/2" peat moss for 2 years. That's how long it took to make it decent.
The vegetable garden was turned every spring for as long as I can remember. When I got my shot at it, I double dug it and added a mix of compost 3/4to 1/4 sand about 3". That year the plants were enormous and my mom freaked out.
So, the best way to improve any soil is, COMPOST.

[TheSolarpunkFarmer]

Yes, adding organic matter is the way! Another easy and effective way to do this is to grow a cover crop. For clay soil you'll want to pick really tough plants with strong root systems like sorghum sudangrass, okra, cowpea, sunn hemp, sunflower, safflower, flax, etc. and grow them in a diverse planting of 8 or more species. In general you tailor your mix to your soil texture and conditions (i.e. low nitrogen availability, lack of structure, the presence of hardpan, etc.). Cover crops pump organic carbon straight from the atmosphere down into the soil in the form of photosynthates, and feed the soil microbes that actually improve the soil in the process. At the end of the season, you'll also have tons of mulch to cut down and feed to the soil, further increasing organic matter levels. I've seen cover crops turn rock hard dirt into dark, friable soil crawling with worms in a single season. They're even more powerful if you combine them with soil amendments like compost and manure. It may take a whole season but it's worth the wait. Plus you can interplant them with tougher veggies that do well in unhealthy soil such as beans, potatoes, and sunchokes.

[vnrkain]

My soil definitely contains clay and my only treatment/amendment has been to continuously add compost and dig it in. The in my present garden is a little over three years old, is now easily dug and turned over and is loaded with worms and all sorts of bug life. Works for me. Cheers all.

[GARDENER]

The one time I had a heavy clay soil, I added 15tonnes of sharp sand & the same amount of organic matter, then rotovated it all in.
The difference was significant both in yield & structure.
This was way back in the 1990s but I still bought your book recently.

[FatherFish]

I have been teaching these same principles for aquariums. Aquarium substrate needs to be soil with a sand cap to prevent leeching into the water. This simple system works miracles in an aquarium. It is a joy listening to you Robert.

[kathrynmettelka]

Thank you for reinforcing my belief that when in doubt, add compost. In Texas 8b, I'm growing on a thin layer of top soil over mostly limestone. You can see the yards and yards of rock wherever roads have been cut through the hills. So I keep adding compost. The plants like it.

[lizhorton]

Great advice. I’ve been gardening for 30 yrs. and I continue to learn. I thought adding sand was bad but I can see the value. However I agree that incorporating organic matter over time is ideal.

[JadeNut]

Great video. I'm currently double digging my garden beds, removing the top 6 inches of heavy clay, then using a fork to aerate the bottom layer of clay before mixing it with mushroom compost, worm casting, and bark mulch to prevent further clodding. I also added live earth worms, red wigglers, and rotting plant matter (mainly vegetables) to further enrich the soil. I'm looking forward to next planting season! Thanks again!

[RRaucina]

Kellogs outdoor potting soil looks great but it is stunting and killing whatever I grow in it. My heavy clayey native garden soil, with sand, composted native brush chippings and lots of manure makes plants thrive. I am done with any "Soil" in bags.
ON EDIT - 2024. Earthgrow steer manure is looking better and my veggie plants are thriving on it. Bought a pallet from Lowes to let it age a year. Used to top a newly seeded lawn - amazing growth and color.

[christiefrenchie]

My local garden center believed that sand would turn my clay soil harder to work; then another source repeated it. I use lots of peat, but have sort-term results. I have a truck load of sand now and will try that. My perennial garden was once a woodsy bog. Raising the garden beds higher is my priority right now.

[kodysherrer]

Charcoal is amazing for our little microbe friends, id definitely look into it for that reason alone.

[redstarrmedia]

I dugout my whole front by hand and sifted it also breaking up the clay clumps just added some compost hopefully I get some good crops out of it as it was back breaking but the earthy smell was relaxing

[jenmiller]

He gets to the solution at 10 mins in. Add organics, compost, manure

[jbc]

I live in Georgia, and have established 2 yards in red clay soil that have been scalped for new construction. Red clay soil is very hard when dry. The following is what has worked for me and is mostly in line with what is stated in the video.
Work in composted pine bark(organic matter). 1 part compost to 2-3 parts soil. Even this amount of organic matter seems to disappear in the soil in a matter of a few years. Work in a thin layer of pine bark nuggets also. These will break down over time and it seems to keep the soil softer longer. Plant your plants. Finally put a mulch that will break down (wood chips, pine straw, pine bark nuggets, finely chopped leaves, etc). The mulch is the key to lasting soil improvement in Georgia red clay. The only disagreement I have for Georgia is the thickness of the mulch. Pine bark or wood chips thicker than 2-3 inches have caused disease problems for myself and others. You could go thicker with straw, probably thinner with finely chopped leaves, but get it thick enough and I suspect you would get the same problem. I am always hoping to find a easier way, but over time for Georgia red clay under your shrubs organic amendments then mulch seems to be the answer.
Additional I'd recommend pinestraw for perennials that sprout from the ground like daffodils.

[StayDownComeUp]

I live in Texas and I want to turn my new property into a big family farm and market garden. The clay is real here. I don't want to amend and plant right away but I want to start improving a large portion over the next year or two. I want to do a till once and never again type of deal.


Everything I watch contradicts the last thing I watched and I have no clue what I'm going to do now lol.

[pearlruth]

Adding sand really helped to loosen that 5-inch layer of topsoil. This summer, I am adding "dehydrated cowmanure". When the June draught hit, my soil retained the water from my soaker-hoses.

[sherrymason]

Thank you. I was told gypsum also but I was worried about it and salt. So I thought I'd add the remnants of the leaves that's almost powder after it rains. My mom adds black topsoil and miracle grow soil to it and plants her flowers. I was even going to buy regular soil to add but wasn't sure if it was wise. In some spots of the land the soil is almost like concrete. Packed hard. The little area I wanted to work isn't completely clay but if I squeeze it I could use it for making pots or bricks. I'm glad I found you on the Google page.

[Optimistforreal]

Thank you, my favorite myth buster! Everybody is talking about clay or sand. My soil is almost pure silt, and a really tiny bit of clay. The garden and neighbourhood is scratch new and I was in need of some more soil to elevate the ground to normal ground level at some places, so I bought some sandy garden soil and mixed in on some spots (only superficially because it is rockhard down there). I tried to grow some plants this year but they remain small and they're having a hard time (probably because the roots cannot penetrate the compacted silt layer) What would your advise be to improve silt soil structure? Till once (minimum depth?), then add mulching every year? Till a few years? Growing green crops and mixing that in into the soil? Just once? Only growing them and cutting them above soil level then mulch? What would be ideal and what would be best I can without spending more money?

[juliknapp]

This is the BEST info I have heard I have been searching info. None of it seemed valid
Thank u!