Potting soil from compost??

I have a source of very cheap compost, and was wondering if I could mix it with anything to make some good quality, but cheap potting soil for large pots and raised beds. The compost originates from wood mulch and shrimp hulls mixed together, and does'nt stink so I think it is well composted?? I can get finely ground pine bark for free, could I mix the two togther?? Should I add anything else??

Thanks!!

All potting soil is sterile and done so to prevent the organisms of soil in interfering with root and infant plant growth. So I don't think that compost would be a good additive to potting soil mixtures until the plant has been added.

This message was edited Feb 7, 2007 3:59 PM

Steve, are you confusing potting soil with seed starting mix?
Most of the general purpose potting soil sold around here is a mixture of compost, peat moss (or more recently coco coir) and perlite. What do they sell in your area?

seastrike, you may want to do a germination test on a sample of the wood mulch/shrimp hull compost you are considering before investing in it, or hauling it to your garden. The germination test is usually done with radish seeds, which sprout quickly. Moisten a sample of the compost and put it in a pan. Place 100 radish seeds on it. Moisten two paper towels and put in a separate pan. Place 100 radish seeds between the two paper towels. Check to see how many have germinated in each pan. You may need to mist them keep them moist until they sprout. If fewer seeds sprout in the compost than on the paper towel, the compost will not be a healthy one to use. If the same number of seeds sprout, then you can use it. I would add a calcium source and innoculate it with beneficial mycorhizae.

The pine bark needs to be well composted before you plant in it.

I often confuse myself with my knowledge. I have thought that potting soil was sterile. Sorry about the innaccuracies.

Well now you made me look! LOL! Some of the bags of potting soil at our garden centers are labeled "sterile", but not all. I guess it depends on its intended purpose. All of the packaged seed starting mixes were labeled as such. Many of the container plant mixes (new name for potting soil?) indicated that they were "rich in probiotics". So there you have it - clear as the mud we play in!

We have a very passive compost pile -- mostly just a big pile of leaves. I use it all the time, without any additives, to plant in. Even if it isn't thoroughly composted. I guess I wouldn't use it for very delicate tiny plants. Maybe. But I've never had any problem at all. I know it isn't supposed to work -- PH isn't supposed to be right, and it is still breaking down -- but it does. And I think the irregular natue of it helps the root system. (I don't use it for indoor plants, because of little critters that might live in it.)

Some how I have confused you GM that I know what I am talking about. Please forgive the deception. I am a simple gardener who because I ask questions sometimes have the answer. Many times it is not the correct one. LOL

happy - I have no reservations with homemade compost because if you make it yourself, you know what went into it. I'm a little leary of "cheap or free" compost made available by someone else (unless you know them really well and know they are good gardeners). We have a sad history of toxic industry wastes being offered to farmers and gardeners as fertilizers. Mind you, I'm not saying that all industry waste is a problem, shrimp hulls could be a good compost component, it's just that I'd prefer to check it out first. Seastrike may have a terrific resource available to him or he could have a problematic waste product. We don't have enough information. Perhaps I'm just overprotective of my soil.

Seastrike : Adding the ground pine bark, you might think twice about that step.
The pine bark hasn't broken down yet and it's attempts to do so, will rob your soil mix of any nitrogen in it's attempts to break down.
Weez bakes her starting soil in roasting bags until the core temp reaches 180*F and stays there for 30 mins.
Hopes this helps................................Dennis aka "the ol'tom cat"................

I switched to bark based soil mixes for containers (especially large ones) and the plants are thrilled. Fertilizer takes care of any nitrogen that might be lost. I would use the compost for the raised beds but not containers or pots.

Seastrike, take a look at this thread if you haven't seen it already.


http://davesgarden.com/forums/t/527353/

Claypa,

What bark based potting soil do you use? What's the brand name? Where do you get it? What sizes does it come it? Do you add anything the soil when planting?

Thanks lots!

Marilyn

I make the mixes on that thread link above, with bark 'fines', peat and turface, some lime maybe and that's about it.
Set aside some time, and read that thread. Better bring a sandwich, it's kind of long. :)

Where do you get the turface? I tried to locate it, but could only find it in massive quantities for developers.

Agway ordered it for me.

I mix compost in my potted plant soil frequently and my plants seem to like it.

And it certainly a good idea to mix compost into the soil for a raised bed.

Wow thanks for all the responses!! The compost availaible is made by the county, at their landfill. I've seen how they make it so its definatly not toxic, maybee full of weeds though. They quite simply mix wood mulch and shrimp hulls, and turn it untill its not hot anymore..They then sell it to the citizens for $25 a ton, but they will only let you get one ton at a time. The reground bark I can get is anywhere from 2 weeks to 6months old. We have a problem with the older stuff catching on fire, so I imagine its at least halfway composted. The reground bark eventually goes to potting soil manufacters, so I know its good for something. Its not a big deal for me to a couple pickup loads for free, I just need to know how to use it. I have alot I want to do in my yard pretty soon, but not a large bank account!!

Claypa, and Joepyeweed,

How much of the bark 'fines', peat and turface, some lime and compost so you use? What's the quanity of each please?

Turface is new new to me. I've never heard of it. Can I order it online from Agway and have it sent to me? What's the purpose of turface in potted plants?

Can you use store bought bagged compost?

Thanks!

Marilyn



















This message was edited Feb 7, 2007 6:32 PM

Marilynbeth, please read the thread on that link I posted at 3:28, because that's just what I do when I have to repot something. If you skip ahead you can find the ratios. There's no one right way, the same plant can grow in different conditions... ....The turface holds air where the roots are.

Seastrike, that sound great, I'd definitely jump at that chance and use it for something... !

Claypa,

Thanks, I'll do that when I have alot more time to read it. And, thanks for posting it.

Marilyn