The GW "Container Gardening" forum has some current threads on this very topic that are very informative. Check it out. Hope that helps.

Your soil choice is probably going to have more influence on whether you're successful or frustrated in your efforts, and how wide your margin for grower error is than any other single variable, so choose well.

You'll find tools that will help you decide what's most foolproof and easiest for you at the link below. You'll even find some recipes that provide good starting points.

Al

This post was edited by tapla on Sun, Mar 2, 14 at 22:38

Thanks!

You are going to be growing things in containers so you want a soilless mix, potting soil,not garden soil or topsoil. Often the potting soil is sold in bags by the gallon so you would need enough to fill 75 gallons.

Making your own container media isn't difficult, and it usually ends up being less than half the cost of commercially prepared soils. Also, if you learn the importance of the air:water relationship in container media and how water behaves in same, you'll be able to avoid the water retention issues inherent in soils based on fine particulates like peat, compost, coir, composted forest products, sand, topsoil, et al.

Al

Thanks for the heads up guys. It's all so confusing and a bit overwhelming. I was hoping someone would say, okay, you need this many gallons of this, this many of that etc to fill 75 gallons but I can totally understand why it's a bit more vague than that.

I have had excellent results from Eliot Coleman's book, The New Organic Grower, second Edition.

I use his Soil Block mix (NB not the mini block mix) for my potted plants. Most commercial potting mixes do not contain nutrients, soil or compost. Coleman writes (pg 138) ""Although most modern growing mediums no longer include any real soil, I have found both soil and compost to be important for plant growth in a mix. Together they replace the "loam" of the successful old-time potting mixtures."" This mix will provide lots of nutrients, particularly the trace elements, so vital to a healthy crop.

Yes, it is more work, but it is truly worth it.

Here is a link that might be useful: Lively Dirt - the Garden Blog

Thanks!

Providing nutrition for containerized plants is monkey easy, so it makes absolutely no sense to sacrifice structure so you can crow about a soil that feeds the plant. Container soils are about structure, not nutrition. Growing in the garden is more than a half a world apart from conventional container culture, which is MUCH closer to hydroponics than growing in the garden.

Everyone can make up their own minds, of course, but it is soo counterproductive to start adding 'things' like topsoil, sand, and other fine particulates that destroy aeration and increase water retention.

No soil is a good soil for conventional container growing if it can't be watered to beyond the point of complete saturation w/o having to worry about a significant fraction of the soil remaining wet so long it rots roots or compromises root function. A healthy plant isn't possible unless the root system is healthy, and a healthy root system is far more difficult to achieve in soggy soils made of fine particulates.

Al

This post was edited by tapla on Wed, Mar 5, 14 at 8:24

Coleman is a master scientist when it comes to growing things. Al, have you studied what he has written... from forty years of experience?

Coleman is not as knowledgeable as Tapla when it comes to container gardening. Al is The Expert, so leave behind your notions of Coleman if you want to learn how to do it right. Tapla has the best soil-less container mix recipes.

If Coleman would like to join us, I'd be happy to parse our ideas about how to get the most out of container media - how to give our plants the best opportunity to realize their genetic potential. I guarantee it won't be in a soil that retains a lot of perched water, like all soils made of fine particulates do. How can you build a case around soils that kill roots when they're flooded and essentially devoid of the O2 that plants need to absorb water and nutrients, let alone the chemical complications anaerobic conditions present?

If you build a soil with the idea in mind that it must provide a favorable air:water ratio for the life of the planting and take on your shoulders the airy burden of providing the nutrition your planting needs, you're on the right track. Stick with the peat, compost, coir, sand, topsoil ..... mixes and you'll be fighting against the limiting effects of the soil for the life of the planting.

Al

Al, you seem to assuming there is a large percentage of soil in Coleman's mix. Not so. You really need to get his book from the library and at least give him a fair hearing. I would love to have him on this site, but I can tell you he is far too busy harvesting, planting, etc.. His mix contains 30 qts. peat, 20 qts. perlite, 20 qts. compost and only 10 qts good soil... plus his fertilizer recommendations. Coleman advocates this as his Soil Block mix, but it has worked very well for my pots.

I needn't assume anything. The percentage of 'soil' in the mix you described isn't as important as the o/a % of fine ingredients. At a glance, just by knowing what's in it and how much of what, you can tell the soil is extremely water retentive. Everything in the mix is fine, with the POSSIBLE exception of the perlite - we don't really know what might be used as far as the size of the perlite goes, but it really isn't important. Even if we assume the perlite is coarse, the soil still doesn't meet the threshold volume for enough coarse ingredients to ensure the fine ingredients won't unfavorably limit aeration. Imagine that you have 6 parts of fine stuff and 2 parts of coarse material (that's how it shakes out, and the 2 parts of coarse is generous). Let's start with the 2 parts of coarse material and call it marbles so we can easily envision all the valuable air spaces between the particles. Now add your 6 parts of fine material. What happens? ALL the large air spaces are filled with fine particles that turn to mud when they get wet.

There are physical laws that can't be ignored because someone wants to grow in compost and topsoil. In order for the perlite to be of any use insofar as an aid to aeration or drainage, it would need to be somewhere around 75-80% of the o/a mix, and the perlite particles would need to be somewhat uniform in size and larger than about .100". Even if his mix was half perlite, the fine particles would simply surround the perlite negating any possibility it would measurably increase aeration or drainage, or reduce the ht of the perched water table. The only + perlite offers in the soil you described is it takes up space that might otherwise be filled with the remaining ingredients, which would be saturated to PWT ht at container capacity - it marginally helps reduce the water retention of an extremely water-retentive mix. Container capacity is the state of water retention after a medium has been saturated and has just stopped draining.

Now, consider a soil that is 75% chunky pine bark and 12% each of peat and perlite. >87% of the mix is chunky, so the 12% peat can't fill all the air spaces between the particles. This means that practically NO water is held between soil particles, almost all water is held on the surface of particles or inside soil particles. That means the soil remains well aerated from top to bottom and the perched water table, if there is one, is insignificant in ht.

Soils like that allow you to flush the soil at will w/o having to worry about root rot or impaired root function, and they allow you to put in place an effective fertilizer program - one that puts the grower in complete control of nutrition and leaves no doubt about how much of what (nutritionally) is available at any given time.

That's the difference between a soil you'll have to fight and one that works FOR you.

Al

This post was edited by tapla on Tue, Mar 4, 14 at 14:44

Al, where can I look at your ideal soil-less mix pls?

"Ideal" isn't a word I would choose. What I push is a concept that has proven to make growing in containers easier and more productive for a lot of growers, and it can be implemented at less than half the price of commercially prepared media based on fine material (peat, compost, composted forest products, sand .....). There are recipes near the end of the thread, if you follow this link, that provide good starting points; but gaining an understanding of the information you'll find there, rather than just following the simple and basic recipes, probably represents the largest step forward a container gardener can make at any given time - that whole give a man a fish/ teach a man to fish thing. The more thoroughly you understand the concept, the more latitude you'll have in implementing it. Still, many are successful just following the basic recipes.

The link is to a thread I started in 2005. The conversation has been ongoing since then, and there have been almost 2,700 posts to it. On another gardening site, the same thread has received over 49,000 views. The info in it has helped a very large number of growers turn their growing experience around. Hopefully you'll find some of the same value others have.

Best luck.

Al

This post was edited by tapla on Tue, Mar 11, 14 at 21:28