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confused about compost....help!

Posted by kawaiineko_gardener 5a (jesusbeloved29@yahoo.com) on
Thu, Mar 22, 12 at 2:12

I'll make this as short as possible; apologize if it's a long post. Mainly compost questions; yet to get straight answer.

Long story short I make my own soil mix (2-3 cubic feet pine bark mulch, 5 gallons perlite, 5 gallons spaghnum peat, 2 c lime, and 2 c fertilizer (osmocote).

Last season when I made soil mix, used wrong type of fertilizer (wasn't suitable for container gardening). Didn't realize this till after soil mix had been made. Had to remake soil mix, didn't have time or money to add correct fertilizer to mix.

Tried to compensate by fertilizing on top of soil w/liquid fertilizer; this made things 10 times worse...stressed out plants and aphids which decimated my harvest. I really don't want to botch my soil mix again this year by over fertilizing.

People keep suggesting adding compost to my mix, my questions about this are....

1. Will compost cause soil too become too compact heavy and/or water log plants.

2.Don't have space to make compost; even if I did, wouldn't be ready in time. Read threads and commercial compost is basically sewage? Is it safe to use?

3.As stated above, I don't want to botch my soil mix by adding too much fertilizer. Since my soil mix already has fertilizer will it be overkill mixing compost in too?

4.If I add compost to my soil mix, should I reduce an amount of one of the ingredients in my soil mix and replace it with the equivalent amount of (that is if I reduce the peat from 5 gallons to 3 gallons, would I use 2 gallons of compost). OR, would I keep the measurements of existing soil mix (one listed above) exactly the same and add compost to the mix? If so, how much per batch? One batch makes 30 gallons of mix.


Follow-Up Postings:

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RE: confused about compost....help!

kawaii, is this question about container gardening or raised bed gardening?


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RE: confused about compost....help!

1. Compost, organic matter, can hold too much water. Commercial potting mixes made of peat moss, coir, or finely ground bark have perlite or vermiculite added to aid with drainage for that reason. What is the one thing most all swamps, bogs, fens have in abundance?
2. Commercial compost is not "basically" sewage. Just what it is depends on what the inputs are. Some makers of commercial compost use the same materials you would at home while others do include treated sewage, biosolids.
3. Maybe. While many people think of compost as just a soil amendment compost can have many plant nutrients in it and you can, easily, over fertilize if you use other sources of nutrients, "fertilizers".
4. Commercial potting mixes are made of peat moss, coir, finely ground bark, or a combination of these with some perlite or vermiculite added for drainage. These mixes are mostly organic matter. Some people have used the compost they make as potting soil for years with no problems, although drainage can be an issue because organic matter does hold moisture really well.
Insect pests can be an indication of nutrient problems plants have, ie. Aphids are drawn to lush, green growth indicative of excess levels of Nitrogen.
Why the lime in that mix? What kind of lime? Since it can take several months for lime to react to neutralize the free Hydrogen ions, that may well be a waste of money unless you male this mix several months in advance of planting season.


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RE: confused about compost....help!

I'd agree with Kimmsr that not ALL commercial compost is sewage. Look at the label. But, I will say that each brand is mostly waste from a single source. Cow compost is manure and bedding for example. That's why Mel Bartholomew (square foot gardener) recommends using 5 different brands. Each one brings different goodies to the party so to speak. I also believe homemade is best. I'd add some. I'd also add mineral soil in your mix, right from your yard. It brings in elements missing from a mix such as you describe. I wouldn't delete anything, just add to your mix and make a little more.


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RE: confused about compost....help!

I've grown tomatoes in containers with as much as 1/3 compost mixed with potting soil (even last year's recycled potting soil). It blends in nicely and will really boost your plants because of the microbes - which are not in a bag of fertilizer.

Curious what was 'wrong' with your fertilizer last year. Unless you used something really odd, it's hard to imagine how that could go wrong. Plants are fairly forgiving.


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RE: confused about compost....help!

The lime is just normal pelleted, dolomite lime. It's not fast asking. I'm just using lime because it's what the my soil mix instructs to add when you go to mix up the batch.

I'm not saying there is sewage in the compost, I'm just based on the threads I read, some ppl think that sewage IS in it. I don't know if there is or isn't, as I've never used compost, either homemade or commercial.

It's not really about raised bed gardening, it's about the type of soil to put in the raised bed.

The thing I'm confused about is, somebody suggested adding compost to the soil less mix I listed above.

However somebody said if there is fertilizer and compost in the mix, it could be over kill in regards to fertilizing.
People say constantly if you add compost to your soil mix, you don't need to add any other fertilizer (like a dry fertilizer, like Osmocote, etc.). Is this true?

The 'fertilizer' I use is a dry, pelleted fertilizer specifically designed for container gardening. It's a 19-12-6.

I really don't know what amount of compost to add to my existing soil mix, as I've never used compost in any shape or form in my mix.


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RE: confused about compost....help!

You don't need to add any compost to the soilless mix because that mix is all organic matter. Compost is also organic matter, it is just more broken down and older. Compost and organic matter are only important when you are gardening in the ground with sand clay or silt and little to no organic matter. Compost is bad for container gardening. I don't know why compost is good for the ground and bad for containers, but I think it may be too rich.


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RE: confused about compost....help!

Okay now I'm more confused....

NOTE: 'They' are people on this forum who do gardening primarily with either raised beds and/or some form of container gardening.

Compost is bad for containers. But I'm not using a traditional container; I'm using a raised bed, which is similar to a container, except that it has no bottom.

It's also placed directly on the dirt. People say since it's sitting on the ground, that the ground acts as drainage.

It was told to me, if you're using a soil mix for raised, beds go more organic, and don't rely on synthetic fertilizers for your primary method of fertilizing.

People who use 'Mel's mix' say that relying on compost alone for the fertilizing of their 'soil' doesn't provide enough fertility, and to amend with fertilizer (like Osmocote etc.)

The only reason I bring Mel's Mix into account is because aren't the SFG beds similar to raised beds, just on a much smaller scale? Basically a miniature version of raised beds?

I'm using the SFG boxes as a basis for comparison with the
raised beds, since the two seem to be similar in the concept with the design. When I say similar, I mean similar in the design of the beds themselves, AM NOT referring to similarities in 'mel's mix' and whatever mix you'd use for raised beds.


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RE: confused about compost....help!

If you are using raised beds, then compost is fine. I put in my raised beds all the time.

But, you don't need to have compost since the mix is made of organic matter. Don't buy compost. It is mostly bark and awful stuff. I only like homemade compost. If you want to bother to make home made compost. That is your choice.

I do use Osmocote, but not a lot of it. I compost so I don't need a lot of Osmocote. But, you can get by with no Osmocote, if you want. Just see how it goes. I find a little bit of Osmocote gives a little boost, but it is not mandatory.

It is up to you, there are no hard and fast rules about using compost or not or using Osmocote or not. The only real rule is do not garden in barren soil without adding organic matter.


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RE: confused about compost....help!

Tropical is right, there are few hard and fast rules.

Compost does have some fertilizer value, on the order of .5-.5 -.5 or 1-1-1 if it's good stuff. That may sound low, but it's typical to add an inch or more to a garden bed and till it in prior to planting. That's a lot more than you would use if it was fertilizer.

When deciding what to do for any situation, the main thing is how your plants grow. Soil and plant needs vary so much that there is no way to make one hard and fast set of rules for what to add to soil. Organic matter, though, like compost, almost never hurts.

Don't get wrapped around the axle from reading tons of advice. Just do it. :-D Observe and adjust.


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RE: confused about compost....help!

The only way you can really know whether your soil has enough nutrients and whether they are balanced is to have a good, reliable soil test done. You cannot guess about this. Adding any kind of fertilizer to any soil without the guidance of a good, reliable soil test is like taking your money and throwing it away.


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