How much is too much compost

[soccer-fan5]

Putting in a raised garden which is 38 cubic feet of space. Wasn't sure of the dirt to compost ratio or if it's a good mix. This is what I bought and I can exchange if needed.

"Pro Top Soil" cheap topsoil (says it has some compost in it) 7.5 cubic feet
"Miracle Grow" garden soil. 12 cubic feet

"ECO" organic compost. 6 cubic feet
"Super Soil" enriched planting compost. 4 cubic feet
mushroom compost. 3 cubic feet

sheep & peat mix 3 cubic feet

"Miracle Grow" potting mix 1 1/4 cubic feet

I was reading about mixes and using different products. Does this sound like a good mix. should I add sand or more potting mix or vermiculite?

Thanks

[ReptileAddiction]

Well IMHO I do not think you can add too much compost. There is a guy on youtube (growingyourgreens) who has a very very productive garden and he fills all his beds with pure compost.

Your mix looks pretty good. I personally would add more potting soil because raised beds are kind of very large containers. The fluffier mix that potting soil has works better for me. You could also just add a bag of perlite or vermiculite and call it good! That would help loosen it up and get some air in it.

[cynthia_h]

I would return the "topsoil." It *may* be an OK product, but sometimes the stuff in bags called "topsoil" is just construction slag, or close to it. Bleah. Nothing that would encourage a plant to extend its tender roots, anyway.

Depending on how deep your raised beds are, you'll want to have larger pore spaces than even many good topsoils provide. Native soils may contain more clay than will drain well in a raised bed; this is why some raised-bed "experts" encourage us to put perlite, vermiculite, or similar breathe-ability products into the planting mix.

ReptileAddiction's advice sounds good to me: perlite, vermiculite, potting soil, or more compost. Any of them will be nice. *Some* clay is good b/c clay contains minerals (aka "micro-nutrients"); my only caution is due to slow drainage in container gardening, and a raised bed--depending on its depth--can be considered simply a large container.

I'm intrigued, though: what is "sheep and peat mix"? Is this one product? If so, what does it contain? Sheep are so incredibly useful to humankind.

Cynthia H.
Sunset Zone 17, USDA Zone 9

[Northernfox]

I really recommend Watching the growing your greens videos on soil. There video I think is here

http://www.youtube.com/watch?v=FH_N92mv ... ata_player

[soccer-fan5]

Thanks for all the suggestions and video's. just moved into a new place in the fall and am sad to see my ground garden go from my last place. Everything grew outstanding there. Wish I could have brought the soil with me. Ill get a couple more items vermiculite, worm castinings and look for the rock dust.
Here is the sheep and peat info.
http://m.homedepot.com/p/Perma-1-5-cu-f ... /100422342

[cynthia_h]

Thank you. "A blend of composted sheep manure, forest products, spagnum [sic] peat moss & gypsum" (description here). It could be terrific! But...

I found only one review, and that person gave the product one star out of five possible stars, saying that s/he screened wood chips and lots of rocks out of the product, and that "the company must compost it on a gravel pit." Too bad; please let us know how the batch you purchased works out. ::fingers crossed for you::

Cynthia

[ReptileAddiction]

That is too bad.

The rock dust in my experience is very hard to find. The big box stores do not carry it and most specialized nurseries do not either. I have only ever found it online.

[Susan W]

We all have a slightly different approach for the dirt aka planting mix. As I have mentioned elsewhere, do my Whatever Mix. This for raised beds, freshening the beds, containers and freshening same. Richness varies for goal.

I use top soil as my base, about 50%. I look for the cheap, and have a couple of brands I will use, but do check, and they are regional. The ones I get have dirt, forest product and sand. I have got a cheaper one that was basically clods of dirt. Then I just add the whatever that may include bagged manure, cotton, compost etc. Worm stuff, home compost, mushroom stuff great additions. The cheaper bagged manure has dirt and sand, both needed. I just can't go adding perlite and vermiculite when the sand is more natural.

For the containers I try to mix a batch in a cart, and start with 1 bag top soil, add this and that, and mix. For the ground just start dumping bags and work it together.

Hope this helps!

[Gary350]

Compost has almost no food value for plants it is just an additive. No more than 50% compost in soil. Compost is great for root growth it makes life easy for the root system. If your thinking of buying compost Peat Moss works great it is the best value for your dollar. Notice I did not say bucks. This is the USA we use dollars not bucks. Add some 15/15/15 fertilizer.

[ReptileAddiction]

I highly disagree Gary. Compost does actually have a lot of nutrients in it. All that good material you throw in there that is full of nutrients, where do you think that goes? Yes some of it does run off with water but quite a bit stays. Furthermore do you think plants in nature get fertilized? I think not. They get nutrients (not all but a lot) from decomposing plant matter. Which is what compost is.

Compost contains a full spectrum of essential plant nutrients.

That is from the Washington State University
http://whatcom.wsu.edu/ag/compost/funda ... nefits.htm

I also highly disagree with the no more than 50% compost. Like I said before there is a guy on youtube (growingyourgreens) who has a hugely productive garden per square foot without using any fertilizer besides compost and that sort of thing. He also fills his waist high raised beds with pure compost.

Please do a google search on some of the things you just claimed. I do not want this to get out of hand so I will stop here but please know that I could go on and on disproving every thing you just said and it is plainly not true.

[mattie g]

I use about 1/3 native soil, 1/3 potting mix, and the rest a combination of compost and topsoil for my 12-gallon tomato pots. During the season I fertilize with compost tea. Seems to work just fine to me.

I honestly think there's less to it than some people make out, especially for those of us growing a garden simply as a hobby and to have some good stuff to eat during the growing months. I suppose you could experiment, but for me it's a trial-and-error type deal. I've found what works for me and my garden, and until my plants tell me otherwise, I'm going to stick to what has worked.

[hendi_alex]

My original raised beds were filled almost 100% with partially composted material and recycled potting soil. Have always had great luck growing most anything in them, even when the depth was only 5-6 inches and sitting on a concrete pad. A couple of years ago I raised the sides to a little over 9 inches. Each year the beds continue to be topped off with one year partial composted material and used potting soil. Results are always very good. Organic fertilizer is used to supplement the nutrients, and if a plant is showing signs of deficiency, will use slow release chemical fertilizer such as Osmocote.

[gixxerific]

Compost has almost no food value for plants it is just an additive.

I don't even know what to say??????

[hendi_alex]

"I don't even know what to say?????? "

Just like raising our children. We have a whole host of right and wrong ideas, but for the most part, the children grow up just fine.

Thankfully, there is not a single right way to go about gardening, and there are few things that must be known with certainty in order to have a satisfactory gardening experience.

[imafan26]

I only add a couple of inches of compost on top of the garden bed at home whenever I plant. I consider compost as an amendment to help build soil structure and encourage soil organisms.

I have planted in almost pure compost. Unless you are also adding fertilizer or fertilizing weekly, the plants will be relatively healthy but not very big from the relative lack of nitrogen. Compost that is not quite finished will compete with the plants for nutrients. Once this type of soil is thoroughly wet, it holds on to water for a very long time. My compost test at a pH of 7.8. I cannot grow acid loving plants in this. Tomatoes that volunteer get to be about 2 ft long and die.

I have clay soils. Too much compost added to it just results in the soil holding on to water for too long and wet clay soil is very difficult to work. It does help with the tilth and cracking and needs less frequent watering. The problem is getting the soil to dry out in the rainy season before the plants die from waterlogging.

Organic matter compacts. It makes the soil denser over time, so I also add cinder or perlite to the soil once in a while to improve aeration. Perlite and cinder don't break down easily, they are essentially rock, so they will not pack down. Sand would also work, but it is also very heavy and the small particle size means I would have to add a lot more. Gypsum also helps to loosen heavy clay soil, but it does take awhile to work and should only be used if the problem is with sodic soil otherwise it can cause more harm than good in the long run. I had my soil tested, it is heavy clay but not sodic.