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Cal-Mag Plus 1 Litre

by Botanicare

Price: $34.99 Loading Data
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Cal-Mag Plus is a highly fortified calcium, magnesium and iron plant supplement formulated to correct common deficiencies. Supplementing your preferred nutrient program with Cal-Mag Plus is strongly recommended when using reverse osmosis water and when growing in coco coir-based medias to compensate for natural calcium draw. Cal-Mag Plus can also be applied as a foliar spray to further enhance growth.

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Product details
Product Dimension: 25.4 x 17.78 x 17.78 cm
Shipping Weight: 1.6 Kg
SKU: 1580

Manufacturer: Botanicare

Date first available: June 12 2016
Average customer review: 4.6 out of 5 stars 16939 customer reviews
Bestsellers Rank: #2 in Botanicare
Customer reviews

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Verified Purchase

April 30, 2022

I gave this to my 5 year old Meyer lemon tree and it made it produce the biggest leaves I’ve ever seen on it. This is all while overwintering it indoors in my shower. Notice the smaller leaves on it, those are the normal sized ones. Never seen it do this before! Looks much more healthy after 6 months indoors than previous winters, where it would often drop lots of leaves (they haven’t been dropping much).

Admittedly I’ve used a little more than I was supposed to than the directions called for and just eyeballed it. I don’t use it every watering, maybe every 3 waterings or so and make it a little stronger than the directions ask.

I also put it on my knockout roses and they went crazy with new foliage. One thing to note, this fertilizer seems to work excellent for new LEAF growth only, not for more flowers or bigger flowers. You have to use different fertilizer for that which I’m not sure I’m allowed to mention here.

I’ve got a decent green thumb so I’ve been able to combine this fertilizer with other fertilizers for more roses on my knockouts without over Fertilizing. I never measure, I just eyeball it and they seem to love it. The key here is lots of water and well drained soils.

One thing to note, with all of this new foliage you’ll get, you’ll be needing to water much more often and in larger amounts so be prepared to pump up your watering schedules and fluid volumes, especially if it’s really hot outside.

In Summary, this is an excellent fertilizer if your plant is well drained but still getting yellow foliage. It will help produce new, abundant and possibly supersized leaves with the right amount of sun, water and drainage.

David Martin


Verified Purchase

September 30, 2020

I'm giving 3 stars because the product seems to have helped some plants, but harmed others. I bought this to help fix an iron deficiency in my avocado plants, as well as provide calcium for my peppers. I have 7 ghost pepper plants and 1 jalapeno outdoors, and a cayenne, chili and habanero indoors. It's too early to tell if it's having an effect on the avocados, but it has messed up my ghost peppers. Today (3 days after using it as a foliar spray mixed in water as per instructions), their leaves were severely wilted in less intense sunlight than they've been getting all summer. The plants had already been watered the previous day (they're watered once a week), so I know it wasn't lack of water. I moved the plants into shade and sprayed their leaves with regular water, which has helped, but the plants still look droopier than before I used the spray. Their leaves are also paler than they were before and some are curling. I'm hoping that they will recover. The jalapeno also has paler leaves and a couple curling leaves, but it didn't look wilted.
On the other hand, the spray didn't harm my indoor peppers. In fact, the habanero and cayenne actually look healthier.
I'm not sure if ghost peppers just don't like this spray's ingredients or if it's not great for outdoor plants (??). Either way, use this product at your own risk.



Verified Purchase

July 10, 2021

So in my state it is legal to crow Cannabis. I thought I would give it a try, so this is my first grow. Early on, my plants looked great and healthy, mainly I think due to the worm castings mixed I added. However around veg week 5 or 6, maybe 7, the largest plant started to show dry bottom leaves, I initially thought it was a water issue or they were not getting enough light. However the problem just snowballed, leaves were turning yellow and brittle. And although I was using coffee grounds, worm castings, and the Fox Farm Big Grow fertilizer... they were still looking a bit sickly. After a bit of research I can to the conclusion it was a Magnesium deficiency. Enter Cal-Mag, the one product that seemed to solve this issue nearly overnight. After making the Cal-Mag solution, the plants' leaves stopped getting spotted yellow, and stopped getting crunchy to the touch. I do think the leaves that were in the process of getting yellow/drying aren't going to improve... however they can be pruned and the problem will definitely not get any worse, so long as I use this product during their watering time.

A1 Product, Highly Recommend.



Verified Purchase

September 03, 2020

While many factors can affect blossom end rot, we have managed most of those very carefully for years and STILL fought blossom end rot... until this year when we tried this product.. We are in CO and have grow, 24+ tomato plants each year for close to two decades, with a variety of slicers and paste - nearly all hybrid varieties that are well suited for both our climate and disease pressure needs. Our drip irrigation is dialed in, on a timer, and we adjust throughout the season - over / under-watering is not an issue. We rotate our crops, supplement with mature compost with a ton of egg shells, have used lobster meal, have a plastic mulch routine... all the usual advice. But every year we'd have at least a third of our plants develop end rot to some degree part way through the season. Not this year! Same varieties, same irrigation, same garden setup, and one feeding with this stuff in early July seemed to halt any rot issues. We have one single paste plant that's had a maybe half a dozen fruit with blossom end issues, but the plant is loaded with dozens more, so we're good. Highly recommend this product!

E. A. Jacques


Verified Purchase

January 30, 2019

I started using coco coir for my indoor grows and was not aware of the need for a calcium and magnesium supplement to buffer the coco before growing. Already half way through the grow cycle and clearly showing signs of a calcium deficiency I decided to give this a try. The improvement was not dramatic, and based on what I read it was not expected, but there has definitely been an improvement.

I will definitely be using this before I start my next grow. I will be using it to buffer my coco with a 150% solution, which sounds like a lot, but does not take much. It will also be a staple to be included in all my nutrient mixtures going forward.

Better late than never I guess. Seems like a solid product and is pretty much the standard when it come to calcium & magnesium supplements. If you need one, I can highly recommend this product.

Yes its Me


Verified Purchase

August 03, 2020

I don't have a vegetable or flower garden but I do own about 80 plants. Some of them expensive tropicals and rare houseplants. I spend a lot of money on supplements and amendments, try everything to make them happy.
Never in the history of my owning plants has anything I've done made such a huge difference. I literally sprayed my plants last night with a diluted spray as another reviewer mention- and came home to some visibly happy plants. Especially my Pilea and Scindapsus, all of which had curled up and deformed looking leaves. My Pilea peperomioides has always, always had curled misformed leaves. I come home today and this one and Pilea raindrop have perky, flat leaves. My other plants look happy as well. And a1/2 a tsp is all it took. SOLD!

Judy L.


Verified Purchase

January 25, 2023

I first bought this supplement over 15 years ago, and use it primarily for tomato plants that tend to need more magnesium and calcium. I found that it helps the plants to develop more and larger tomatoes and also helps to prevent blossom rot. I have also used it on bell pepper and have had fantastic yields from my plants. Incidentally, I grow all of these indoors, and often have more tomatoes and peppers than I can easily use. I can't personally attest to this supplement being good for all plants, but it is definitely beneficial for plants that tend to be deficient in calcium and magnesium.

I hope this review was helpful for you.

Heather T


Verified Purchase

July 22, 2022

I have been using this brand of cal-mag for a while after I learned that your tomatoes will be much happier with it. I first started using when the leaves were turning funny and I had to do some research. I mostly use this in my aerogardens with 5-10ml/week depending on the unit. My tomatoes have been happy ever since. With summer here I just dosed up one of my outdoor plants that is in a grow bag that is probably too small. This will help it get through the season. This brand does the trick and it seems the most cost effective out there too.

Leonard Perry


Verified Purchase

September 03, 2021

I started using this product mid-summer and wish I had found it sooner. My tomatoes were suffering from blossom end rot along with spotted leaves. I began applying this to the entire plant either first thing in the morning before the sun came up or late in the day, once every three days. My plants started producing more fruit that was bigger, greener, and more healthy almost immediately. I would highly recommend this product to anyone growing tomatoes, and I will be using it all season long next year.



Verified Purchase

January 22, 2023

Since my thumb turned green back in 2007ish, this is the only product I’ve kept in the rotation as companies switch it up often and mess up a good thing trying to improve something that works perfectly. Botanicare has been solid since Day 1.

The other Botanicare brands I’ve used for 12+ yrs religiously are the Liquid Karma and their Coco Coir 5kg brick which is good for 5 or so Three gallon pots and runs around $20/5kg (make sure you charge it up prior to sowing your seeds/clones).

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