Unless there is no calcium in your normal fertigation, then I wouldn't use it at all. I and many others use a very fast draining container mix, and sometimes it feels we are using a semi hydroponic setup, especially with a soilless container mix. But like Dave said, BER isn't caused by lack of calcuim, but poor distribution of existing calcium, possibly due to inconsistent moisture levels, and I'll add, rapidly growing fruit, since BER seems to occur earlier in the season.

I think that stuff is just really pricey lime (calcium carbonate). To the extent you feel driven to use it regularly, be aware that it will deacidify soil pretty readily, so if you already have alkaline soil, it could be harmful. That it, it isn't the calcium that you should be concerned about, but the hydroxide. I agree that most complete fertilizers will probably have calcium added, since it's really cheap to add (lime!), so I suspect it's not even deficient in your soil. FWIW, both perlite and vermiculite have some (slow release) mineral calcium, and those are probably already in your potting soil.

it's good to use if you're growing with peat based or coco soil-less type media. if i recall, it contains some trace amount of iron as well.

the stuff is potent so be sure not to over do it. 1/4 tsp a gallon is around 150ppms which should be plenty every other week along with your regular feeding schedule.

"it's good to use if you're growing with peat based or coco soil-less type media. if i recall, it contains some trace amount of iron as well."

Since you are routinely fertilizing anything grown in a container - or you should be - I fail to see why this would be needed if you use a decent water soluble fert with a full range of micronutrients. All the Ca or Fe or whatever else you feel is necessary is already provided.

I guess the question for the OP is what fertilizer you're using for your container plants. Are you convinced that it doesn't contain calcium? Container gardening pretty much demands a complete fertilizer, so adding specific nutrients seems like overkill if you're doing what you're already supposed to be doing.

> Since you are routinely fertilizing anything grown in a container - or
you should be - I fail to see why this would be needed if you use a
decent water soluble fert with a full range of micronutrients. All the
Ca or Fe or whatever else you feel is necessary is already provided.

because if you read my comment, i mention coco-peat based mediums which are generally used in containers. do you know about CEC? (cation exchange) read up here: https://www.pthorticulture.com/en/training-center/what-is-cec-cation-exchange-capacity/

in other words, outdoor garden soil tends to hold on to micronutrients, (calcium/magnesium,etc).. while soil-less type mediums tend to leech out and not be available in abundance.

on top of that there are a lot of fertilizers that do not have all the proper levels of nutrients simply because they are generally formulated for garden soil and not soil-less mediums which they tend to lack nutrients when growing in containers..

Again, assumptions are being made that one is treating containerized plants the same as those planted in the ground. But I believe many experienced container gardeners: a) consider a peat or coir based soil mix inferior to begin with and opt for something more durable and less moisture retentive (ergo, no ProMix); and b) understand that fertilizing container grown plants is also approached differently. Neither pH nor CEC are limiting or restrictive factors for container gardening as they are for inground plantings simply because of the frequency of fertilization - weekly, weakly (at least).

And since I use a Dyna Gro product to fertilize my containers, I am assured they are getting ALL the nutrients they need and find no need to add other, typically unnecessary, supplements.

1. Hi Everyone,

3. I'm very grateful for your help and advice--it has really helped a lot. Between your advice and a little soul searching, here's what I'm learning:

5. 1. I use two types of fertilizer--liquid Miracle-Gro and also solid pellets. The liquid stuff does not have calcium in it as well as a couple other items. The pellets seem to be a little more complete so I'll try to stick to those.

7. 2. I agree with everyone--it is likely that low calcium in the soil is not the problem. I'm guilty of frequent, shallow watering and this is more than likely a problem. I'm reading in multiple places to water deep and less frequently, allowing a small amount of water to run out the bottom of the pot--this is something I haven't done.

9. I'll adjust my watering habits.

11. Thank you again for your help!