Gypsum or lime with coir/bark/perlite mix

[walkinggin]

After poor results from my container grown tomatoes last year, I'm going to try Raybo's 3-2-1 mix except replace the promix with beatspeat brand coir blocks. I know coir is supposed to be ph neutral therefore gypsum is preferable but I'm not sure about the bark and whether it affects the overall ph of the mix enough to require the addition of dolomite lime.

Or is it possible that neither is necessary with the homemade compost, mycos, actinovate, tomato tone, micros, kelp and molasses that I will also be using?

I'd like to keep it as simple as possible.

ginny

[rnewste]

ginny,

If you have multiple containers, I would give my 3:2:1 Combo Mix a try in one, then experiment with variants of coir, microbark, Perlite. to see which ingredients and ratios work best for your locale. Remember, aeration is key to successful container growing, so be careful of compost and other ingredients which could choke off getting air to the root system.

Raybo

[walkinggin]

Actually, I have been thinking about trying a few with the "Raybo classic mix". As for the compost my intention is to keep that a very small percentage of the overall mix, so in terms of a 3-2-1 situation the compost would at most be 1/2 a part and maybe I'll rethink that, its not like I can't find other uses for good compost. My in ground tomatoes love it.

I'm using open containers and I learned the hard way last year where my mix was about 60% compost. In my climate it broke down to sludge in no time flat.

ginny

[dice]

The bark will break down fairly slowly, over about 5 years. You might not
need to raise the pH at all this year, then use maybe 1/2 dolomite, 1/2
gypsum in it next year (if reusing the coir-bark-perlite; I would test it
first next spring with a pH tester, though).

[fortyonenorth]

Ginny - The primary problem with low pH is that several of the micronutrients become super-available when pH drops under about 5.0 and can reach toxic levels - toxic from a plant's perspective, that is. However, this applies primarily to mineral soils - not organic "soils" that are commonly used for container mixes. So, with this in mind, container-grown plants will thrive in a much wider pH range than the same plants growing in your garden beds.

Pine bark has a natural pH in the 3.5 - 4.5 range. If added in small proportions to a pH-neutral substrate (such as the coir mix you mentioned) it wont' adversely affect the pH. However, you still need lime to provide calcium and magnesium. If you're using a balanced fertilizer which includes calcium and magnesium you can skip the lime and/or gypsum altogether. If not, you'll need to provide them. I'd use dolomite since it has the magnesium as well. If you prefer, you could use gypsum for calcium and epsom salts for magnesium.

[dice]

I was thinking the 1% magnesium in Tomato-tone (0.7 % water soluble)
plus whatever traces are in your other stuff might be enough, so you
may not need epsom salt if you use gypsum for a calcium source
(Tomato-tone ingredients include sul-po-mag).

I usually top-dress containers where the media has been amended with
gypsum with a couple of tablespoons of epsom salt at the start of the
season and do not sweat it after that. We get plenty of rain, and I have
not seen magnesium deficiency symptoms in the container plants.

[walkinggin]

Thanks for the responses. I'm thinking that I'm probably over thinking this and since my main problem last year was poor drainage improving that by eliminating the compost will be a big help. I will probably try a few containers with a 5-1-1 bark-perlite-peat combo in addition to the 3-2-1 mix to see which I prefer.

I'm also beginning to wonder whether I should bother adjusting either of the mixes at all. I have very hard water with a ph that averages slightly above 8 which might help neutralize the container "soil" ph while supplying cal and mag above what is in the ferts I use. Except that I'm not sure it works that way. The water analysis I get lists:

PH 8.1
hardness ppm 230
Boron ppb 170
calcium ppm 62
magnesium ppm 19
potassium ppm 3.7
sodium ppm 50

ginny

[sprtsguy76]

Ginny I use the 5-1-1 mix exclusively, its a great mix. I wouldnt worry about PH too much especially if your liming and using pine or fir bark as the main ingredient. If you must you could use your compost as the '1' part in the 5-1-1 in place of the peat. I've used several different water retaining mixes in place of the peat with good results. The key in my opinion is to limit that stuff and keep it to no more than 2 parts. Good luck!

Damon