Compost Mix for My Square Foot Gardens?

First off... I've never been a gardener, but I want to start in the spring of 2021. To that end I have been reading and planning.

I've been reading this book called "Square Foot Gardening" written by Mel Bartholomew. It appealed to me because not only has the method enjoyed widespread success, but because it seems simple and logical. He is an engineer that took up gardening as a hobby when he retired, and wanted to follow a logical approach that appealed to me.

My question is this:

I built these raised beds that I'm going to plant in and I need to fill them up. In Mel's book he recommends equal parts of: Compost, vermiculite and peat moss. However I have this pile of compost that I got delivered from a local landscape company that I want to mostly use. It's good looking stuff and based on the areas of my cabin yard that I have filled in with it, it appears to be very fertile. Here's the problem... It has all kinds of weeds in it.

We want to have a mostly organic garden, so how can I kill the weeds (Basically sterilize the compost after I put it into the frames.) without using chemicals?

My first thought is to take some black plastic and cover the frames after I fill them up and hopefully the black plastic will cause the beds to heat up so much that the heat will kill any seeds.

Any suggestions?

Pics of said gardening area for people who like pictures...



The compost is in the background next to the pile of crusher run.

Black Kow is what I started my raised bed with.

I considered cow manure.

Did you fill the whole bed with Black Kow?

Did you mix it with other stuff?

just black kow, I did turn over the ground level before I filled it.

Just use the compost you have and get another truck load if you need it. Definitely want to add something like vermiculite to keep it from getting compressed over time. If you don’t want to use an herbicide, you can shade out the weeds with a tarp or mulch/wood chips. You can also add in some lime and fertilizer when you lay it down to get mixed in and watered in well.

Throw your veggie scraps, wood ashes, egg shells, coffee grounds, etc in there when you’re done with them and you’ll keep it pretty fertile.

You have shallow beds, you must have a strong back. Most Co-Op’s sell bulk potting soil. You can haul it on a tarped trailer or pickup bed. Fill your beds and add a few miracle grow bags. Keep composting and add soil every year. I would tarp your existing soil and add it to the beds over the years, happy gardening and good luck with the organic approach.

Yeah... We have been contributing to a compost pile for over a year now. All our scraps, coffee grounds, etc... have gone in there so we're getting a pretty good sized pile now.

In The Square Foot Gardening Book, Mel recommends a mix called "Mel's Mix" that is 1/3 Peat Moss, 1/3 Vermiculite, and 1/3 Compost and he doesn't end up fertilizing at all. He and his followers have been getting great results using that for years.

So I guess I'm off to the store to get peat moss, vermiculite, and probably manure too, as well as some black plastic.

Gin trash. We put a good bit of gin trash in our little garden spot and it seemed to suppress the weeds somehow. If it were me, i would go get a pickup truck load of gin trash. Hoe out your beds. Lay landscape cloth down. Fill up and round over with the gin trash. Plant veggies and watch them grow.

Ill tell you something i saw a hippie gardner doing. He put a thick layer of hay over his garden and planted directly in the hay. I asked him how hw kept the grass out of it. He said grass wouldnt grow in it because the hay was too thick. You do have to add more hay occasionally as the lower layers break down.

I have had raised beds for years and the general mix Mel recommend is fairly common in raised bed gardening. Truly, the mixture needed depends on where you live. The primary objective is to keep the soil from compacting so your crops can grow...spread their roots so to speak. Till that bottom to try and kill any weeds and grasses growing and lay garden cloth to inhibit any further growth. You will need some additional additives besides your compost and I have found potting soil works great as well as the bagged raised bed soil. One thing I did was put red wigglers (worms) to help keep the soil from compacting.

I am pretty much organic and even with raised beds still pull weeds occasionally. My beds are considerably taller than yours, thus not as many weeds. I have one short bed about the height of yours and have more problems with weeds in it. Even so, you have less problems than in ground gardens do. The black plastic over them is a good idea to help.

If you add fresh manure, make a tea and water with it. Fresh manure is hot and can burn your garden. It needs to lay out for a time to mellow. Know several who swear by gin trash too but I have never used it personally. I redress my beds annually with about the top three or four inches of soil. By the time things settle and you pick crops, you tend to lose a few inches each year.

Also, remember to rotate your crops so the same plants are not in the same beds annually. Lastly, ants tend to be a problem with raised beds, so pay attention to that. Wishing you great success. There are a few threads around showing my beds. Fortunately, I have had great success and hope you do too. One last thing...your pics look a bit on the shady side, so be aware of how much and where your sun shines and plant accordingly.

Pile all those leaves in the beds, add your compost and till away. Add some lime in also. Sow Crimson clover on it for green manure in the spring. You can grow carrots through the winter. You can come back and put newspaper around your plants and cover with compost or soil to suppress weeds.

Thanks for the advice and well thought out response.

I think I am fortunate in that the dump truck load of compost that I bought and have now put in the beds appears to be really good soil. It also appears, based on my observation, to already have a healthy population of earth worms in it as well.

I went to Lowes and bought a bale of peat moss and 2 bags of manure to amend each 4'x8' bed. (4 bales and 8 bags total.) I still need to find a good source of vermiculite on Friday and then I'm going to get them all mixed up and ready to plant some stuff as early as February. I'm probably going

In all honesty, I almost feel like I have bit off a little more than I can chew with 4 - 4'x8' beds. I drew up some plans of each bed:

One bed is going to be entirely herbs
One bed is going to be entirely salad stuff.
The other two beds will be all kinds vegetables.

When you start planning the thing out, using the Square Foot Garden recommended plant spacing, it's kind of daunting when you realize that you can grow 16 carrots in one square foot. I probably should have started with just one or two of the beds, but it is what it is, and it will be a fun learning experience.

Thanks for the advice.

If the weeds start to get out of hand I may try the newspaper trick. Not sure about the clover though... In a raised bed.

Thanks for the advice. I need to research the Gin Trash more. This is the first I have heard of it.

You will do fine, I am sure. Once things start growing, you will find that space fills fast. Best of luck with it and if I can answer any questions, just pm me.

One last thing, I do not care for the straw/hay business in my beds. That stuff sprouts!

Landscape cloth gin trash and litter should do it

I bought a Compost Tumbler years ago and that sucker works like a charm. I will open it in the summer and steam is rolling out of it.