How much lime per square foot?

Mamachibi 8/6/2011, 10:51 am

Lots of people have been complaining of blossom end rot. To avoid it, I know we can add lime to tomato plots. So, a couple questions:

1. Besides tomatoes, what other plants can have added calcium to avoid blossom end rot and other calcium deficiency problems?

2. What is the recommended form of calcium? Greensand? Lime? Other?

3. What is the recommended dosage of calcium per cubic foot/2?

4. When is the recommended application of calcium? At transplant? Flower set? Fruit set?

I want to get my ducks in a row and my schedule set! (Yeah...not a perfect world, I know.)

littlejo 8/6/2011, 11:52 am

I personally would not use lime. It takes several months to really do any good. I would use gypsum (in a bag) or some human calcium tablets, crushed. Lime also changes the ph of the soil, which you probably don't need.

I don't know the dosage, I just sprinkle some on the soil. Mix if you can, but watering will get it into the soil. I would do this when transplanting, before they start blooming if possible.

Only other plant that I know that needs calcium is peppers. Lack of calcium causes the pepper leaves to sort of bulge in the middle.

Jo

boffer 8/6/2011, 12:23 pm

Good questions all. But a more holistic approach to the BER problem might help us to manage the problem more effectively.

BER is not a disease; it is a physiological disorder; it is not transmitted from plant to plant. This summary is from Cornell University.

Blossom-End Rot (BER) - Characterized by a large, leathery brown or black spot on the bottom of the fruit. It generally occurs on the first fruit cluster. BER is caused by a lack of calcium in the fruit which causes the fruit to die back creating the characteristic spot. What can you do to prevent it? Have your soil tested to make sure calcium is present in adequate amounts. Chances are your calcium level will be fine but if it is not, add limestone (for acid soils with a pH below 6), or gypsum when the soil pH is in the 6 to 7 range. If calcium levels are okay, the next most important control is to maintain optimum soil moisture. When tomatoes experience the slightest bit of drought, BER may result. Using mulches will usually significantly decrease BER as excessive evaporation from soil is reduced. If growing on bare ground, avoid cultivating too close to plants to prevent root damage and the need to maintain deep root development. Varieties will vary in their susceptibility so if you have a problem with a particular variety, choose a new one next year. When side-dressing plants, using a nitrate type fertilizer like calcium nitrate is preferable to ammonium based ones like urea. Finally, don't bother to use calcium sprays. They are worthless in combating the problem. The same problem can occur on pepper and eggplant.

Some important points listed:

It generally occurs on the first fruit cluster. It is suspected this happens because the soil is too cool for the plant to extract the calcium. As the season progresses, the soil warms, and the following clusters don't have problems.
Chances are your calcium levels are fine. Calcium is not scarce.
Maintain optimum moisture levels. Easy to do with MM. Mulching may be an advantage for most of us, but may be required in hot, dry climates.
Varieties will vary in their susceptibility. Just another factor we have to make adjustments for.
Use the proper fertilizer. Not an issue with MM.

BER is most frequently caused by the plants' inability to extract calcium from the soil, not because of a lack of calcium in the soil.

Properly adding calcium doesn't hurt things, and it gives gardeners a sense of satisfaction for being pro-active. It should used as part of a program, and not considered a cure-all.

stripesmom 8/6/2011, 2:57 pm

I've read (some where, so can't give a reference) that crushed antacid tablets don't provide the calcium in a form your plants can use. I don't know, if it's true, but I'd rather not worry about one more thing. So, I've been using 1 tbs of powdered milk in a square once a month or so and have had no evidence of ber. In fact, I've never had such huge, perfect looking tomatoes in my life. I also add a tbs of epsom salts with the powdered milk as the magnesium helps the plants take up the calcium easier. Oh, also, I water my gardens (by hand with a cup) morning and night unless it rains, which it seems to not want to do anymore.

littlesapphire 8/6/2011, 3:09 pm

Wow, thanks for all the great info, guys! I'll certainly keep that in mind if my toms ever show any signs of BER.

BackyardBirdGardner 8/6/2011, 8:15 pm

Boffer covered it well, but I still thought I'd mention...

If using Mel's Mix, BER is less of a problem as long as you keep your moisture level consistent. Adding amendments becomes largely obselete. I have never added calcium to my tomatoes since converting to SFG....haven't needed to. This is the type of thing the concept of All New SFG is designed to eliminate from our lives....including the science, workload, and cost that goes along with amending soils in any way. I HAVE had BER on a couple fruits, but it's a rare occurence.

**camprn** 8/6/2011, 8:20 pm

I have had a discussion with my Ag agent about adding crushed limestone and he recommended applying it in the fall to be a readily available micronutrient in the spring. I used recipe MM in my new tomato bed & I am having BER issues and will be adding limestone and compost as part of my fall cleanup and winter prep. I am not sure about application amounts and I plan to research this before applying in the autumn. I may also send out MM samples to be tested. The latter depends upon my pocketbook.

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