Dolomite lime, is a very special way to leverage the use of lime—its uber bacterial friendly—while buffering pH exactly within, or towards, the most favored pH range of most aerobic bacteria. AKA—the good guys! Cannabis highly prefers a bacterial dominant soil.
For this article I will be discussing dolomite lime, and to a lesser extent, lime, for use when container growing cannabis in truly living soil. Native ground soil normally has a very low ratio of organic matter, compared to mineral components. Container soil, on the other hand, has a very high ratio of organic matter, compared to mineral components. Why does this matter? Decomposing organic matter usually drops the pH (when you add water) in the area of decomp. Drops it too low for most cannabis varieties, for reals, without buffering.
So, the bottom line is that you need some calcium to keep the pH in check; potassium will also raise pH. This way, as the decomp proceeds in the containers’ living soil, the pH is kept from diving too low. Lime, is essentially calcium carbonate (calcitic lime). Dolomite lime is essentially calcium carbonate, and magnesium carbonate. Coincidently, cannabis plants use a lot of calcium, and magnesium; especially during flowering. Let’s rock and/or roll…
Dolomite Lime (DL) is a True Buffer
Just straight-up lime, can take your pH way the hell up. Like pH 11, or higher. This is of course, an almost instant death sentence to your plants. Unlike just typical lime, dolomite lime holds a pH of just about 7.0, so it will tend to bring the pH back to 7.0, no matter if it was higher or lower beforehand. Most of the bacteria you want highly active in your soil prefer this pH. It’s a good thing.
The thing is, whenever you water your containers, stuff happens, tons of stuff. Below (see dolomite lime water), I will show you guys how to buffer your water source with dolomite lime, while also supplying Ca (calcium), and Mg (magnesium) to your plants this way. But for now, basically, the wetter (including air) your living soil is, the more action is occurring. Chemical reactions, related to the decomposition of organic matter. Microbial life is also simultaneously, rapidly growing and colonizing. This will almost always tend to dive the containers’ soil pH to some extent. Dolomite lime keeps this in check (buffered) very well.
Whenever I am recycling soil, or making new soil from bagged soil for friends, I use a pretty standard ½ tablespoon of DL, per gallon of soil. 1 cubic foot of soil is approximately 6 gallons of soil. So, 3 tablespoons per cubic foot of soil. Of course, I include other sources of calcium carbonate as additions to my recycling soil. Like, oyster shells, bone meal, crab meal, gypsum, etc. Soil additions must be allowed to process in the moist soil for at least 2 weeks before using that soil for plants—FYI.
If I were just doing something like goosing up some bagged soil, with blood, bone, and kelp, say, I would use about 1 tablespoon of dolomite lime per gallon of soil mix. As a stand-alone buffer. Then of course this soil needs to “cook” (decomp) for at least 2 weeks before use.
Too much magnesium sucks badly! If you are already adding a lot of Mg, and/or your soil/medium contains high ratios of Mg, you may want to use calcitic lime, not dolomite lime. Some well water is high in Mg. Too much Mg left over in your plants at harvest will make them smoke harsh AF—almost as harsh as synthetically grown cannabis. Yuk!
Also, raw lime kills soil life and plant roots. Never add lime of any kind to your living plants’ soil. It needs to be processed for 2 weeks minimum in living soil before plants are introduced.
You always want powdered dolomite lime. You can use pelletized (sometimes called prilled) DL as well, and this is fine as long as it is also FAST ACTING (see photo above). What you do not want, is dolomite lime in the form of hard little rocks, that is not fast acting.
Dolomite Lime Water
If you are familiar with making living teas for your plants, the process is exactly as like. You just need an air-pump, air-line, and an air-stone (the air-stones made from sand are the best). Get a container of whatever size your gardening requires. Fill with low PPM water, 55 PPM or less. Bubble 1/8th teaspoon of DL per gallon of water for 24 hours. At the end of 24 hours your water should have a PPM value around 55-65 PPM. Perfect! This makes PRIMO water for your plants. Far better than using low PPM water alone in containers.
When it is done bubbling, remove the air-stone and wait for 15 minutes. Carefully pour the DL water off the top, leaving the last 10% of the water and sludge. Pour DL sludge water on outdoor plants or trees if you like. Boom! You have your awesome cannabis plant water. This water works exceptionally well on cannabis sprouts too. All stages of growth.
This water modification is super effective for you if you are using rain water to grow with. Or, if you have super hard water and you use a reverse osmosis filter, or even if you use distilled water. Any low PPM water source can be turned into primo growing water this way. Always check PPM before using if you store this water before use.
Lime Sources and Uses
- Calcitic lime is good for using in like, raised beds outdoors in custom soil, with native soil below that is already high in magnesium. If your water source is unusually high in dissolved magnesium, and/or liquid fertilizers you use are high in Mg.
- Hydrated lime is a severe dosage of highly available calcium, too high for living soil, unless used in nano amounts. Hydrated lime can easily kill your plants in a day or two after transplant from an overdose. I have seen it used highly effectively in soilless, organic container gardens, using liquid organic nutrients on a regiment. Nutrients high in organic acids.
- Garden lime is normally just calcium carbonate, but I have seen dolomite lime labeled as garden lime. So read the labels carefully.
- Diatomaceous Earth (DE) is another excellent source for calcium carbonate (lime). It also contains silicon. Many plants can take or leave silicon; however, I think cannabis plants really put it to good use and it makes a fairly big difference. Empirically gleaned opinion.
For more all natural (supernatural) growing advice check out my book, True Living Organics 2nd Edition. And, if you are looking for some truly exotic cannabis seeds, pop on by Kingdom Organic Seeds, and have a looksee. The Riffraff Thai is back baybee. 😈
L8r G8rs, here’s another article you might dig on by yours truly, Blood Meal – Skunk Magazine. See ya all back here next week at SKUNK! Hang in there…
I'm The Rev, and I have been with SKUNK for about a decade now. I hail from Southern California, spent mucho time in Northern California, and now reside in Southern Oregon; always coastal. I am an all natural style cannabis grower and I have written a couple books on the subject - check out True Living Organics 2nd Edition on Amazon - I have been growing for over 45 years, and I have been breeding cannabis for over 30 years. Check out kingdomorganicseeds.com to see some exotic selections. Growing connoisseur cannabis is what I teach mostly, growing it in living soil without using liquid organic nutrients to feed the plant. I am also a highly skilled synthetics grower, hydroponics, aeroponics, DWC/SWC/NFT, Ebb and Flow, and soilless, but I cringe when smoking synthetic grown herbs, so for the last 15 years or so I preach the artisan style of all natural growing, specializing in container growing. Cheers and welcome aboard.