Starting a Raised Garden this Year - Leaf Compost Only??

by Tom
(Northwest Ohio)

I am starting a "Raised Garden" for the first time this year about 4' x 12'... I have plenty of composted leaves, some from 4-5 years ago.. I collect leaves each year from 2 acres of lawn each year with a leaf vacuum attached to a lawn tractor. The mower chops the leaves then the vacuum chops them and blows into a hopper... I then dump them in a pile.. Each year I move to another location to dump..Some are well composted and look like black earth...

Question: Can I use 100% of the black composted leaves for the raised garden and not aid anything else?? The soil here is hard clay and not good for digging.. Is there anything else I need to add if I use 100% black 2 + years old composted leaves???


The Compost Gardener Answer

This is such a great question Tom and it's one a lot of people have.

Here are two pictures of my front garden. The first is partway through sheet composting my lawn. There are newspapers down in order to eliminate the lawn. This was done Fall 2009. In the spring I planted into the soil below this mulch and by fall 2010 I had what you see in the second picture. It did need a winter to breakdown and kill the lawn. I think, were I to do it again I would peel the sod off the lawn and then begin.

Some popular gardening books treat soil as more a problem than a resource. In fact in Mel Bartholemew's All New Square Foot Gardening book he recommends taking soil right out of the equation and substituting peat moss and compost. I love his book for the information on plant spacing and organizing but this removal of soil is something I believe is wrong.

This doesn't mean you can't have success planting in straight compost. One of the people on a forum I participate in says it this way:

  • I "CAN" grow buffalo grass on top of very "weak" compost or mulch.

  • I "HAVE" grown buffalo grass sod on top of a concrete slab. 

  • You "SHOULD" grow buffalo grass directly on top of "SOIL".

Plants grow best in soil. Your soil, being clay will give you challenges but it also offers advantages. Clay soils are generally high in nutrients. Their problems lie in the soil structure. Organic matter is the key to improving your soil structure.

What I would do is wait for that magic moment when you can
work clay soil. That is when it is neither too wet or too dry. You should be able to squeeze a handful into a ball and have that ball stay a ball. When you poke the ball of soil, it should break apart.

I'm assuming the raised bed you are planning in on the ground and that the surface vegetation has already been removed. Use a fork to do a little loosening of the soil where you are putting your raised bed. You don't want to turn it, just put the fork in and wiggle it back and forth. You can add soil to the bed area from around the bed to define your pathways and build up the raised bed a bit. Then add your composted leaves. Let the worms be the ones who dig the leaves into the soil.

A raised bed should be just soil covered with 3 to 4 inches of compost/mulch. The compost is on top of the soil. The mulch, if used goes on top of the compost.

When you plant, plant into soil after you push the compost aside. If you get weeds cut the plants off flush with the ground. This material will be fully colonized by microbes and will break down adding to your compost mulch layer. Eventually it will be brought down into the soil improving it.

You may not have a brilliant garden in year one but it is worth the effort to improve your soil. By year 3 you'll be laughing.

If you still have the layer of lawn or other plants on top of your planned raised bed it depends on how fast you want your garden to grow. Given it is Spring I would skim off the sod. Pile the sod up root side up. In a year or so you can use it to add to your beds. The other solution - the lasagna method is best started in he fall with a kind of sheet composting.

Work with the soil you have rather than bringing in new soil. When I was growing up my parents were big buyers of topsoil. Every few years they bought a load of topsoil and spread it over everything. This soil always had a weird smell and to be honest we never had a half decent garden. My grandparents made compost and spread it every year. Their garden fed them and was great.

Hope this helps. Feel free to get clarification by making a comment. Good luck and happy soil building.


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