Do I need lime in this mix?

[creister]

I am going to grow tomatoes in buckets and HEB this year. I have done it in the past with peat based mixes such as Pro-Mix. I added 2 cups lime to HEB, and about 1 cup to 5 gallon buckets. I have lime and gypsum. I know at Earthbox website the instructions say to use dolomitic lime. Can Gypsum be used instead?

This year, I am using a recipie to make my own. I am wondering if I need to add any lime to this mix.

Mix:

40% coir fiber
40% compost
10% expanded shale
5% lava sand
4% alfalfal meal
1% greensand

I know there is calcium in alfalfa meal and that coir fiber is not as acidic as peat moss. I also have very alkaline water. I have some plants in 5 gallon buckets and some in 18 gallon HEB

[stormymater]

Do you have one of those garden pH meters? That might be really helpful. There are not really expensive (<$10), have 2 prongs you plunge into the damp soil & a digital readout. Might help you out.

PS - hope that lava sand is not from Hawaii - Pele is down on folks tating her lava off the islands!

[creister]

No pH meter, maybe ought to get one. Not sure where the lava sand is from.

[newatthiskat]

LOL stormymater. I remember them talking about Pele when I was down in Hawaii a couple of years ago. Turns out it was a tourist guide that started the whole story about bad luck. It sounded more mysterious than them saying "it is unlawfull to remove anything from a state or national park"
KAT

[dice]

You should be fine for pH. You might want to add a cup
of gypsum for more calcium (in addition to what the
alfalfa and greensand have) and the sulfur in it.

Dolomite would also have provided magnesium. I am
guessing you are using some fertilizer with this mix.
Does it include magnesium?

(Note that the greensand, lava rock, expanded shale,
and alfalfa may also all have some modest amount
of magnesium, very slow release in the first 3, so you
may be ok on this regardless. A couple of tablespoons
of epsom salts per container would insure it.)

[creister]

Thanks for the answers. I will be adding fertilizer to this. I contains 4% calcium and 1% magnesium. 2 cups to the 5 gallon and 3-4 to HEBs.

What happens if too much Ca is added? Another question:

I will be growing some summer squash in the above mix, and some in peat based potting mix. Do I need to add lime to HEB for squash? I have never grown squash in containers.

[creister]

I will be using the same fertilizer in all containers. It is Espoma Biotone Plus.

[dice]

I don't know what happens if too much calcium is added. If the
pH is too high, calcium and phosphorus will form insoluble
dicalcium phosphate, but if the pH is ok, a surplus of calcium is
probably better than not enough.

If I recall correctly, you have high-calcium soil, and you might
have high-calcium water, too. If the water has plenty, maybe
you can skip the gypsum. If the plants in your containers root
down through the bottom into the high-calcium soil below them,
that would also handle it for those, because the roots should
reach down into that calcium reservoir about the same time
that the plants plants are setting fruit (unless you move them
around in the yard).

Apparently squash gets blossom end rot, too, for the same
reasons as tomatoes. It reportedly likes a pH between 6.0
and 6.5 (most efficient for calcium uptake), and it will
probably do fine up to pH 7.2.

Edit:
I do not expect that the extra handful of gypsum can hurt, and it is
good insurance for calcium availability. You could try some of the same
cultivar with and without it in the same size container and see if you
notice any difference.

[dice]

PS: Too much calcium results in tie-up of trace elements.
Too high a pH ties up phosphorus. Results of both usually
take a few years to show up in field soils:

http://www.kinseyag.com/Article2.htm

To answer your original question, do you need lime in that
container mix, I would say no, do you need more calcium,
maybe. Hard to say without a chemical test of some kind,
that would include testing the container mix, your water,
and your fertilizer, or a comparative growout with and
without specifically a calcium source added in addition
to what you already have there.

Blossom End Rot is a real annoyance, so I tend to err on the
side of too much calcium rather than too little, while at the
same time taking pains to avoid raising the pH in soil or
container mix that tests 6.0 or higher (thus I mostly use
gypsum rather than lime for a calcium source). With your
high calcium soil, this is probably only an issue for containers,
and it may not be one at all if your water supply is calcium-rich,
too.

[creister]

Thanks dice. I will have four containers for squash. Two for yellow and two for zucchini. I will grow the yellow in my potting mix, and zucchini in peat based mix. I will then add gypsum to one zuc and on yellow container and gypsum to the other two and see if there is any difference.

[creister]

I my last statement I meant to say to add lime to one zuc and one yellow, and gypsum to one zuc and one yellow.

[dice]

That sounds like a good plan to me. Even if one or the other
does not do so well, it is not as if you will be lacking in zuccini.

[creister]

You are right about that! One year I planted over ten plants. I must have picked over 100 pounds. Never again.