Ground limestone is almost almost pure calcium carbonate and comprises the largest % of all lime used in the United States - it is abundant and the cheapest form of lime. Also, it is not caustic or disagreeable to handle like burnt or hydrated lime. It may also contain varying amounts of magnesium carbonate. Limestones containing significant amounts of magnesium carbonate are called dolomitic limestones. Dolomitic limestone contains about equal parts of magnesium and calcium carbonate. Hydrated/slaked lime Â
pound for pound is about 1-1/2 times more effective (at raising pH) and quicker to react than ground limestone (calcium carbonate). There are other forms of lime, but they're not generally something you'd want to use in a container.

Al

I was just coming here to ask a similar question! I was als o wondering which limestone I should use in my containers if I was more interested in increasing the calcium level than raising pH. (My soil mix already has a good pH for what I want.)

If interested in only Ca, use ground limestone. If you want Mg too, use dolomitic lime. I use dolomitic lime in containers.

In container soils, pH is far less important than in mineral soils. You could drive yourself crazy chasing a "perfect pH", and it's not necessary. In container soils, when ions attach to organic particulates they are loosely held and available over a wide pH range, in contrast to mineral (garden) soils. Your (our) job is to make sure they are there in usable amounts.

Al

A1, for a less abrupt change in calcium levels, bone meal is about 15% usable calcium. The drawback of bone meal is that it attracts animals that are looking for the bone. In any case, I spread it on top of the snow just before the last frost date as an early spring tonic. BTW, bone meal that is used to mix with chicken feed is just fine to use in place of the expensive bone meal sold for spring bulbs. The only difference is the stuff used with chicken feed is much finer than the horticultural bone meal so it breaks down faster and costs about 1/10 the money. Sandy

Thanks for the info, Al! It's good to know I don't need to obsess over pH, as I'm not great at measuring exact amounts of ingredients when mixing stuff!

Thanks to all of you for your great comments !!!
By the way AL, what is your container soil mix ??

I have had many people thank me (several recently) for sharing this recipe for container soils for both pretty & yummy container plants:

5 parts pine bark (partially composted works best, but fresh will work fine)
1-2 parts sphagnum peat (no sedge, reed, or Michigan peat, please)
1-2 parts perlite (it comes fine, medium, coarse. Coarse is best.)
dolomitic lime
slow release fertilizer
micro-nutrient source (not compost, please) Available as powder, granules, fish/seaweed/kelp emulsions, Earthjuice, or use a fertilizer that contains the minor elements. I use about 1/4 - 1/3 cup of lime per cu ft of soil and about 1/3 cup of slow release in the 19-6-12 range. I still supplement regularly with a balanced liquid fertilizer (20-20-20 usually) and various combinations of fish emulsions (I use both 5-1-1 and 2-3-1).

This soil will easily go an entire, long grow season with almost no structural failure (soil collapse or soil that breaks down and begins to hold too much water) and would likely be structurally sound for a second year, but I do not reuse container soils.

Al

Came across your comments while searching for anything about lime. A neighbor of mine told me that he puts lime in his yard to combat fleas. Ever hear such a thing?
Thanks,
BC

Blossom end rot in container grown tomatoes is a common problem, and more likely linked to water fluctuation than an absence of calcium. Calcium deficiency is possible, though unlikely since most commercial potting soils have lime added and most water contains at least some calcium. I would recommend using dolomite lime if you are mixing your own soil, since it contains magnesium as well.
(I've stopped using lime in my own soil since my water is loaded with calcium, magnesium and other minerals.)

Al's soil recipe would be a great choice for container tomatoes, since it would definitely help you avoid over-watering and water-logged plants. I'll be mixing up a cu. yd. this weekend, and I'm very much looking forward to it--nothing like the smell of pine bark and peat and the anticipation of spring.

Jason

bcra5006 I lived down south one year and rented a home with a large yard. You could not walk through the yard without the fleas and mosquitos destroying your feet and legs. When the high humidity of summer kicked in they infested the house and moved in underneath the house so my foggers that i had using for WEEKS did not work.

At the end of my wits I went to a bug removal expert who casually pointed out lime repels insects. I bought a 40 lb bag of Agricultural lime and crawled under the house and laced it completely with lime then moved on to the yard. Having hardwood floors I lightly dusted the inside of the house, then vacated it for a coulple days. When I came back there were no more fleas, mosquitos, or red ants in the yard, not a flea to be found in the home and to my surprise dozens of cockroaches lying dead everywhere on the hardwood floors. The Lime attacks their bodies orifices drying and burning them to death. It's a hard clean-up inside but it was worth it, and cutting the grass spreading it around and removed the white powder on the grass. I hope this helps someone!

I want to try Steve Soloman's COP fertilizer mix..I found the pulverized dolomitic lime but can't find agricultural lime..Is this commonly available anywhere?

I used lime that I bought at home depot and that is generally used for plaster ? I think lime is all the same.

I asked this question on a different thread but thoyght id try here since i havent got an answer... Is organic epsoma garden lime ok to use in the 511 mix?

Nevermind it says right on the pack dolomitic lime...lol. Sorry...

All lime is not the same. And you need to really be careful when adding Dolomite lime (and K-Mag) bc it has too high of a Ca to Mg ratio and you will have way too much Mg if you use it as your only source of Ca. Also, in ag lime "additional chemicals vary depending on the mineral source and may include calcium oxide, magnesium oxide and magnesium carbonate" (Wikipedia links in green).

Folks, many of the questions asked here are easily answered with much more reliable information if you do your own research on Google as some of these replies are providing incomplete or inaccurate information.

You have the internet and all the information it contains at your fingertips. Put it to use for some research and you will have information that you can be much more confident about and you did it essentially on your own.

For those who want the real scoop as to what this stuff really is and how it affects your plants:

Ag Lime:
http://en.wikipedia.org/wiki/Agricultural_lime

Hydrated Lime (Calcium Hydroxide):
http://en.wikipedia.org/wiki/Calcium_hydroxide

Dolomite lime:
http://en.wikipedia.org/wiki/Dolomite

Gypsum:
http://en.wikipedia.org/wiki/Gypsum

Hope that helps.

Lol - I think I'm dumbstruck - just as well .........

Al

LOL!! I would never consider wikipedia to be a wholly reliable reference for anything. How can it be when the information it contains is contributed by anyone who wants to put in his $.02 regardless of experience or credentials? It's not a bad place to start to gather some basic data from which to engage in real research (or as one place states, to settle a bet with your roomate!) but as an accurate source on which to base methodology and practices, especially with something like container gardening........???? No flipping way!! That anyone would suggest that as a substitute for the practical, experiential and in some cases, scientific knowledge base demonstrated in many of the GW forums is ridiculous.

For those of us who may not know for sure, and are willing to learn, what exactly is it in those Wiki articles that is 'wrong'? Getting information from more than 1 source can be a very good thing. However, it also, at times, can cause confusion.

Most information on Wikipedia is annotated. When it isn't, there is a notice posted on the page.

Even reliable, reputable sources can be wrong, an earnest person or reference realizes that fact and adjusts their attitude accordingly. I use Wiki often, and along with other sources, will continue. That said, if they are indeed wrong on something, it would sure be good to know.

Well again, it's great for reference. But if you want to learn, say, how to grow a peace lily as a container plant, all you get from Wikipedia is this:

"It lives best in shade and needs little sunlight to thrive. It is watered approximately once a week. The soil is best left moist but only needs watering if the soil is dry."

This really doesn't give you much to work with. Is it wrong? Not exactly, but someone could easily get the idea that the container soil should be dry all the way through before watering. Meanwhile there is a huge amount of information about peace lilies in this forum, and you can submit photos of your own plants when asking questions that help the answers to be tailored for your particular situation.

Where in any of the Wikipedia articles on lime above does it say what type of lime to use for container plants, or how much to add?

Last comment reported as spam.

oops--the the spam has been removed, I certainly didn't flag WoodsTea's comment!!