To go all geeky (as an ex-chemist) it is a multi-variable question. The kind of pot, the kind of soil, the kind of watering, and the kind of climate affect it all.

Personally, if Smart Pot told me I could try heavier I'd at least try one pot with the old time soil based mixture: 1/3 garden loam, 1/3 compost, 1/3 sand. And then try the more exotic (in the sense of being trucked in) solutions after that.

Of course, I'm running drip irrigation right now, and enjoying the flexibility that gives me in tuning the watering schedule for my few tomatoes, eggplants, and peppers.

I'd suggest you go over to the Container Gardening forum here with this question. Much more container users there. While there you might want to read about the 5-1-1- mix many of them recommend.

Personally I discourage anyone from using ANY soil-based mix in containers because it compacts and drains poorly and that leads to slow root development and root rot. Most any of the peat-based soil-less mixes work far better in my Smart Pots.

Dave

Here is a link that might be useful: Container Gardening forum

I guess I'd be interested in hearing from anyone who tried the traditional mix and had trouble with it. It might be early but it seems to be working for me, with well draining black nursery pots and drip irrigation.

(Image: my mix)

Size on 3/24

size on 4/25

johns.....what kinds of tomatoes are those?

QUESTION:
what makes those pots "SMART" ? Do they have computer chips built in ? :)

What makes the pots "Smart" is the manufacturer's marketing team. They can call their product whatever they want, and decided to market it as "Smart Pot."

Other manufacturers of similar products have other names for their products.

And here is the manufacturer's web page, which explains what its alleged advantages are over traditional containers and why the manufacturers think that using its product is smarter.

Here is a link that might be useful: Smart Pot manufacturer's page

This post was edited by DHLCAL on Tue, Apr 29, 14 at 4:41

I got it. It is just a fabric bag.

So it drains from the wall and can also get air from there. I have bought some grocery store shopping bags. I did not know they are smart. @ 89 cents each, it sound good and smart BUY> hehe

Super sweet 100, Reisentraube, and Early Girl.

I guess I'd be interested in hearing from anyone who tried the traditional mix and had trouble with it.

John, there are many discussions about the problems associated with what you call "traditional" mix. over on the Container Gardening forum if you want to read through them. Check out the ones about declining porosity, nutrient deficiency issues, water movement and retention, etc.

While your mix can be effective in large garden beds assuming there is an adequate soil micro herd for the compost to supply nutrients, the lack of those bacteria and microbes and the confines of a container can create problems when using it in them.

Over the years I have tried many different mixes in my containers of various sizes and the overall plant health, root development, and plant production (in my climate) is by far the best when I use a soil-less mix in conjunction with drip irrigation and fertigation.

JMO

Dave

Here's the thing Dave, many university agricultural extension services still cite the traditional mix as an option.

I understand the soil-less mixes. I made them when I was in high school. When I was student labor at an arboretum I ran the box mixer and made yards and yards of it. It has many strengths, including uniformity and light weight.

I guess I just (like those extension offices) am not ready to say "never" to the the old time mix (which really did come first).

There is a good line in this University of Vermont article:

"In some ways, compost is like snowflakes, no two batches of compost are exactly alike."

But then, as we see on these forums a lot of energy is spent because few bags of bark are alike.

Here is a link that might be useful: POTTING MIXES FOR ORGANIC GROWERS

Here is a University of Florida document which lists the soil based option.

(Perhaps the confusion is that attempts to use straight soil put the soil based mixtures in a bad light - but no one would suggest pure peat for tomatoes either. The "mix" is the key.)

Here is a link that might be useful: Homemade Potting Mix

I understand what you are saying John. I have been in the nursery business for over 50 years now and I know how things have changed over those decades. Sadly I also know how very outdated much of that info one can read online is.

Add to that the need they feel they have to try to cover all points within a brief page length (so some will read it) and one finds all sorts of issues hidden between the lines.

In the article you linked for example they skim lightly over the issues of "free of pathogens and seed-free", of "density and disease concerns", "hold nutrients well", etc. assuming the reader will know how to prevent all those issues - issues that kill more container plants than all other issues combined and so easily avoided by simply using a bagged already sterile mix.

They make no mention of the size of containers and even imply these "mixes" will work in any container. They don't discuss how one is supposed to evaluate "density" or recognize what is good or bad density. They don't address HOW one is supposed to retain nutrients when daily watering is often needed.

I could go on but but as I mentioned above all this is discussed and debated in infinite detail on the Container Gardening forum as it is only indirectly related to Growing Tomatoes.

Bottom line - the choice of what to use is yours. I have tried them all over many years and IMO container mixes that incorporate coarse sand (except for succulents), top soil in any of its various forms, much less garden soil and even compost pose far more problems for plants grown in containers than any potential benefits they might have.

Dave

I can understand and agree with most of that Dave, and certainly if I were in a commercial setup, looking to produce hundreds or thousands of plants all the same, a repeatable soil-less mix would be my choice too.

Since we are in the tomato forum though, I'll refine what I sad.

I think that for large (5 gallons and bigger) containers and for a single season of growth, a mix with good soil, good compost, and good sand can work. I wouldn't ask anyone to go whole hog on it, but if you have the materials, trying a pot or two (which was all I suggested up top) might be worth it.

Of course, it takes a little experience to know what a good potting soil looks like, and good soil, compost, and sand.

(I'd be quite unlikely to use soil based mixes myself for small pots or indoors)

So I just measured. My Super Sweet 100's are 40 inches tall today.

They started 6" on March 24. That's basically 35" in 35 days.

That's pretty good isn't it? Especially considering that they only get about 5 hours of direct sun?

I mean if it's not good, and soil-less mixtures are kicking all over that rate, I am ready to be educated.

(I'm afraid I can't say the exact ratios in my mix, it was a little of this, little of that, but 60% plant material, 20% soil, 20% sand might not be far off.)

Can't offer you any comparative measurements as my tomato plants can't even be planted out yet here. So they are all just 8-10" tall transplants living in the greenhouses.

You have several distinct advantages in your climate that most of us in the rest of the country envy on a regular basis. Let's compare notes long about end of July. :)

Dave

I'm actually trying the tomatoes in a place where they say "don't try" or "needs 12 hours direct sun." I have learned that heat matters too though, and the west wall behind the tomatoes has helped in a cool overcast April.

It was mostly 60's and 70's and then BOOM.

Santa Ana winds today and we blasted up to 97 in the sun.

(I found a reference that said tomatoes should "double" in 12 to 15 days. I am at the slow end of that, with about 15. I feel good about that though, given the coastal zone.)