I am hesitant to make any recommendation as I don't know the particulars.

How deep is the salad table? By deep I mean how many inches of mix will it hold? What are the length and width?

Also, how dry/wet is your climate?

The reason I am asking all these things is because normally I would recommend a mix with really sharp drainage, but if this table is what I think it is then it's shallow in depth with a lot of surface area. If your climate is also dry then water is going to evaporate quickly in such a container.

I will answer your question in a more generic way: A commercial potting mix using peat, vermiculite and perlite would be approximately 70% peat, 15% vermiculite and 15% perlite. Some mixes such as those labeled 'organic' often will have something similar to Bumper Crop soil amendment in it. It's composted bark, composted wood and some organic nutrient sources like chicken and worm poop.

Often those mixes are 40% peat, 40% Bumper Crop (or the equivalent) and the rest perlite. This is an approximation as the mixes do vary a bit in terms of each ingredient's percentages.

You can consider the Bumper Crop product a substitute for compost.

In other words, I am not making any recommendations, but trying to provide you with more general info.

Thank you, JaG. You are indeed correct regarding the table style. ;) My table is 3.5" high, and each section (2) is ~15x30". If all goes well with this method, I've already planned on increasing the height this fall.

The climate is currently wet, but I'm sure it's mostly dry (no sarcasm intended--really). I've lived here for less than a year, so I couldn't tell ya that one...

Your "general info" is very helpful. To cut down on the weight of the soil, I think I may use the %'s of vermiculite, perlite & peat you provided, then combine that into 70% to 30% Bumper Crop (hehe. that comment makes me feel all smart en' stuff)... What do you think?

I think it makes for a good starting point. If you find yourself having to water more often than you would like you can modify it to hold more water (next season). On the other hand if you find yourself with a mix that stays wet a long time and the plants don't like it you can modify it to provide more drainage.

Gotta start somewhere, right? It's a balancing act between a mix that holds enough water for the plants until you can water again while still offering enough drainage to get strong plant growth.

The mix you are considering would be quite similar to some of the 'organic' mixes on the market so it should be fine.

I think that with the shallow depth and wide surface area you may need to water fairly frequently. This is actually a good thing as far as the growth of the plants is concerned.

Have you read Al(Tapla's) post on water and air movement in containers? It contains a wealth of info on what goes on inside a container and how to build a terrific potting mix. If you haven't read it I encourage you to do so as I think you will come away feeling a lot more confident in choosing ingredients/percentages etc in response to how things go for you this season and what you liked/didn't like.

I am really glad that you posted this momma s! We made the table this past weekend and I went by the Martha Stewart directions that said you could use 1/2 soiless mix and 1/2 compost. When I went shopping all I could find was Pro mix and composted cow manure. Because of your post I went back and read the whole thing again.

Use a 50:50 mixture of a "soil less" growing media with good compost (e.g. LeafGro- a compost made in Central MD from leaves and grass clippings).

Do not use animal manures in the Salad tables or Salad Boxes.

Unfortunately I already mixed and filled it. Does anyone know why you can't used composted manure?

Here is a link that might be useful: http://forums2.gardenweb.com/forums/load/contain/msg0310252423115.html?5

Unfortunately I already mixed and filled it. Does anyone know why you can't used composted manure?

None.

The idea of using composted anything is controversial to say the least in containers, but in this specific application I, personally, don't see a real issue with it as the table is likely to dry down and require watering at a reasonable interval with a heavier mix.

The risks with manures (pathogens that can infect humans) are for raw manures, not fully composted ones. The risks of making the mix "too hot" are again, for uncomposted manures, not composted ones.

Can't think of any reason why composted manure would be a problem in a scenario where composted whatever would not be.

It's much more critical when growing in shallow containers to use a soil that holds no, or very little perched water. It's not at all unusual for bagged soils or a homemade soil of fine particulates to support 3" or more of perched water. If the soil DOES hold 3" of perched water, and we allow 1/2" of freeboard at the top of the 2 x 4, the soil will be 100% saturated after watering and until the excess water evaporates, or the plants use it and air can return to the soil. This is where the balancing act comes into play, and you'll always have this dilemma when using shallow containers unless you keep soil particle size large enough.

Perhaps you should consider employing a few wicks that will 'fool' the excess water into 'thinking' the container is deeper than it actually is, to help you eliminate some of the excess water it sounds like you will have until the planting matures, or permanently, if required.

Alternately, you could include a large fraction of pine bark in the soil mix and eliminate your soggy soil worries.

Al

Al makes a good point with the wick. I struggled a bit in replying to this post because of the shallow, but wide surface area of this table combined with a zone 9b versus my zone 5.

While a shallow container does make the perched water table particularly problematic, it also makes evaporation and transpiration (plant usage) problematic.

Early in the season with fairly cool conditions and small plants the presence of the PWT is a problem. Later with warmer temps and larger plants the intensively planted area and shallow soil may present a challenge in terms of frequent waterings.

A wick is a very good solution. Use it early on and if/when watering frequency becomes more frequent than desired remove it for more water retention.

We made our edges with 2 by 6's to add a little debth. Thank you for your answers and suggestions.

momma s how deep did you make yours? I wish I'd done 2 by 8. It will be interesting to see how well it works.

JaG~ I've read several of Al's posts on soil and clipped the one for water movement/retention for later, but I got to them a bit late for this season... I'll study more over the summer to prepare for the fall semester--I mean season. ;-)

Why is using compost/manure in containers controversial? Would it then be unwise to use compost tea on containerized plants or for the salad table? I'm considering this since I already have it on hand (and so I can use it up this season & purchase materials to make Al's mix this fall hehehe).

never-give-up~ I made my walls with a 2x4, but I'm pretty sure I'll add another 2x4 this fall if all goes well with the table. There's more flexibility in what can be grown (obviously) with more depth, and that excites me.

Al~ So, saturated soil, even in full sun (when it's not too hot) and dry weather ins't a good thing since the table is shallow (please forgive my ignorance)? Should I water less then? I stay at home, so if I need to water more frequently until the plants are established, it wouldn't be too much of a pain...

Why is using compost/manure in containers controversial?

Because of it's small particle size. Particles under 1/16th of an inch or so won't drain completely. There will be a soggy wet layer of potting mix that plants generally don't grow well in. The more shallow the container the greater the problem. The concept is explained in Al's Water/Air movement thread. It is also explained in this Ohio State University fact sheet.

It isn't something you need to worry too much about this season. Use a wick in the drainage hole if your potting mix is staying wet/soggy. Would it then be unwise to use compost tea on containerized plants or for the salad table?

No, not at all. Compost isn't bad in and of itself, it is just the small particle size and the fact that it breaks down into even smaller particles as the season progresses that is the problem in containers. So, saturated soil, even in full sun (when it's not too hot) and dry weather ins't a good thing since the table is shallow

A saturated soil is fine. What is problematic is when the soil isn't just saturated (holding all the water it can), but it is also holding water in the spaces between particles that would otherwise be filled with air. I am confident that once you read Al's water/air movement thread or the link I put above you will understand what we are talking about better.

But again, don't fret too much for now. A wick, if needed, can alleviate much of the potential problem. Once the plants are of any size and the weather is warm/dry I don't think you will have any problems. Still, understanding the concepts will put you in a very good position to respond to whatever occurs.