Can I or can't I use 100% compost in my raised beds?

[tedln]

garden5,

Yes, it may have been damping off. I planted cucumber and summer squash in the 100% compost just to see if it would support plants. I planted them really late in the summer when the day light hours were a lot shorter. The cucumbers germinated and grew 8 or 10 inches before dieing. One plant even put out a few blooms before dieing. Less than 50% of the squash even germinated. The ones that did germinate grew a couple of inches before dieing. I haven't decided if the compost simply wouldn't support them in the 100% strength or if the plants I chose were simply not appropriate for the late season in which they were planted. I'm thinking about putting a wheel barrow of compost in a pile in one corner of my garden this spring and planting some stuff in the compost pile just to see what they will do.

Ted

[Jbest]

On the right are Butterbush squash and on the left are potatoes. All are growing in 100% compost. The potatoes exceeded 4' high before harvest. John
[img]https://www.jbest123.com/wp-content/uploads/2009/09/P7200899-560x420.jpg[/img]

[tedln]

Hi jbest. I love your journal. I also appreciate your thoughtful approach to gardening. I was aware that you are growing in 100% compost. I think your compost is more chemically and nutritionally balanced than my purchased compost. Given time and the possible addition of some micro nutrients my compost and those like mine will eventually be as balanced as yours.

Ted

[Ofer]

I once did an experiment for a big nursery for new varieties of lawn.

I used to have a big plot so we had 10 sq/m of 4 varieties X 2

All of it was grown on just compost! My lecturer from Uni was the organizer of that. true I was surprised too. But it is actually great.

If the compost is not new- no problem.

[gixxerific]

If I can afford it I will be getting about 4 yards of compost for my garden, yard, flower beds. So I hope it is good to use a lot of it because that is what I will be doing. The compost should be good if the Mo Botanical Garden are cool with it than I am too.

This shall get me going to where I can be at least mostly self sufficient with my own compost. I don't see any reason all compost would be bad, what is good soil but degraded vegetation and what is compost, the same so.........

Of course if you want to be more fungal a good leaf mold would do better than a greener compost.

[Joyfirst]

I grew things in raised beds made mostly with compost(square foot gardening recommneded) and things grew nicely. Next year I added composted horse manure and it grew even better. I thought it would be just large leaves and not much fruit, but it was both. My community garden neighbours actually asked me what do I put in my soil!

[Halfway]

Hi jbest. I love your journal. I also appreciate your thoughtful approach to gardening. I was aware that you are growing in 100% compost. I think your compost is more chemically and nutritionally balanced than my purchased compost. Given time and the possible addition of some micro nutrients my compost and those like mine will eventually be as balanced as yours.

Ted

I believe Mel suggests using multiple composts from dealer sources to achieve a balance. This makes sense if the compost is made of one or only a couple different ingredients such as horse manure and sawdust.

Yard waste and kitchen scraps gathered and composted throughout the year would naturally provide a much more balanced compost.

I will be supplementing the beds with potting mix this year as I do not have enough compost ready. It will look to be around 15% compost, 25% vermiculite, 25% peat, and 35% potting soil.

[gixxerific]

Variety is definitely good, and remember all that variety eventually becomes more or less compost. So the more the better.

Compost on!

[jal_ut]

The seeds would germinate fine, but the plants would slowly wither and die.

This is a classic case of the soil being too HOT. In other words too many available nutrients in the mix. (this is also the reason you have to water straight compost beds so much) If you can take a mix like that and add it as an amendment to real topsoiil at a rate of about one part compost to 5 parts soil, then you have something that will grow plants.

[jal_ut]

On the right are Butterbush squash and on the left are potatoes. All are growing in 100% compost.

What is under your beds? Do you have any idea how deep your plants roots go?

https://www.soilandhealth.org/01aglibrary/010137veg.roots/010137toc.html
Every gardener should look at this page.

[jal_ut]

BTW this is what squash grown in real soil looks like.

[img]https://donce.lofthouse.com/jamaica/crookneck_plant.jpg[/img]

[Jbest]

BTW this is what squash grown in real soil looks like.

[img]https://donce.lofthouse.com/jamaica/crookneck_plant.jpg[/img]

Sorry jal_ut but it makes a difference on the weather, how long the squash were growing and what type of squash. In the photo below the bed is 10" deep, 40" wide and 14' long and the 100% compost produced 29 squash averaging 1 1/2# each. Also our weather last summer was the worst growing weather I can remember, cold and few sun days. John
[img]https://www.jbest123.com/wp-content/uploads/2009/09/P9040001-560x690.jpg[/img]

[jal_ut]

John,

My reason for giving you the link to a paper on plant roots was so that you could see that the roots of squash can go as deep as 6--7 feet and as far as 12 feet or more lateraly in all directions.

The point is that you may say you are growing in 100% compost but truth be known, that little bit of compost is only a drop in the bucket of what area your squash roots will gain water and nutrients from.

Unless you have a bottom on those beds to keep the roots from going further? Basically, what you have done is provide a good mulch on top of the ground your beds sit on. Your plants will get a good share of their nutrition and water from the area below and beyond your compost.

Does this make any sense, or will you still say you are growing in 100% compost?

[Jbest]

John,

My reason for giving you the link to a paper on plant roots was so that you could see that the roots of squash can go as deep as 6--7 feet and as far as 12 feet or more lateraly in all directions.

The point is that you may say you are growing in 100% compost but truth be known, that little bit of compost is only a drop in the bucket of what area your squash roots will gain water and nutrients from.

Unless you have a bottom on those beds to keep the roots from going further? Basically, what you have done is provide a good mulch on top of the ground your beds sit on. Your plants will get a good share of their nutrition and water from the area below and beyond your compost.

Does this make any sense, or will you still say you are growing in 100% compost?

How would you explain the success that people have with the SFG style of gardening. Some of which are on concrete driveways or with bottoms and elevated on legs for the patio? Most of them use a soilless mix or straight compost and they have very attractive harvests. Or potatoes grown in bags of commercial potting soil and other container gardens. John

[tedln]

My raised beds had about 10" of compost/soil mix in them last summer. In two 8'X4' beds, I planted my yellow crook neck squash plants along the edges with my tomatoes in the center of the beds. I harvested more than one hundred lbs of squash during the season. Some of the vines were so long, I tied a rope to the outer ends and lifted them to the upper rungs of my tomato cages just to keep the squash off the ground.

At the end of the season, I pulled all the squash vines and tossed them on my compost piles. I found all of the vines were very shallow rooted with none of them extending more than eight inches into the soil. I guess they may have the ability to extend very deep and spread wide, but if they are receiving all the moisture and nutrients they need in the prepared soil, they simply don't extend very far.

They may also have realized that the natural "soil" under the raised beds is very rocky, hard, and nutrient poor.

Ted

[tedln]

The seeds would germinate fine, but the plants would slowly wither and die.

This is a classic case of the soil being too HOT. In other words too many available nutrients in the mix. (this is also the reason you have to water straight compost beds so much) If you can take a mix like that and add it as an amendment to real topsoiil at a rate of about one part compost to 5 parts soil, then you have something that will grow plants.

Interesting thought! While I was thinking along the lines of insufficient nutrients, you believe the opposite. I do remember once reading a thread in a compost forum that said a high wood content in compost will severely reduce the available nitrogen while the wood is decomposing. Since my purchased compost was primarily saw dust with horse manure and horse urine, I kinda lean to the insufficient nutrient side. I will know better this spring when I plant my spring garden and see how the new plants do in the compost.

Ted

[jal_ut]

It is easy to make a test. Take some real soil, some sand, and some compost. Get 4 4 inch pots. In one put soil, in one put sand, in one put compost, and in the fourth use a mix of one part of each soil, sand and compost. Now plant 2 bean seeds in each pot. Water and put them in a sunny windowsill. Water as needed, and see how each mix works to grow the plants. Then decide for yourselves.

[farmerlon]

On the right are Butterbush squash and on the left are potatoes. All are growing in 100% compost.

What is under your beds? Do you have any idea how deep your plants roots go?

https://www.soilandhealth.org/01aglibrary/010137veg.roots/010137toc.html
Every gardener should look at this page.

Thanks for sharing that link ... that looks like some thoughtful and useful information!