General Discussion:

aluminum sulphate

Messages posted to thread:

tim20-May-02 12:36 PM EST 5b   
Deborah23-May-02 06:29 AM EST 6a   
Carol25-May-02 03:23 PM EST 5a   
Lee26-May-02 10:49 AM EST 6a   
Deborah31-May-02 06:32 PM EST 6a   

Subject: aluminum sulphate
From: tim
Zone: 5b
Date: 20-May-02 12:36 PM EST

can anyone tell me what the most effective way of applying aluminum sulphate is. dilution ? at what ratio?

Subject: RE: aluminum sulphate
From: Deborah
Zone: 6a
Date: 23-May-02 06:29 AM EST

Hi Tim

Aluminum sulphate is sold as a rapid acidifier for soils, but frequent use can be problematic due to build-up.

If acidifying your soil is what you'll be using it for, I'd suggest that a better product might be flowers of sulfur, which will turn into sulfuric acid in the soil over a few months. It's available from most garden centres. The amount to use depends on soil texture. In sandy soil, 8 pounds per thousand square feet will lower pH (and acidify your soil) by about 1 point; in heavy loam soil, roughly 25 pounds would be needed.

Peat moss is also an excellent product for lowering pH, works more gradually than flowers of sulfur, and has the added advantage of improving the soil.

A soil testing kit is a good investment, to know what your pH level is now, and to know the results of amendment.

For smaller areas around shrubs needing acidic soil (ie rhodos, azaleas), I usually just dig in peat moss mixed with compost all around my shrubs, to a depth of 4-6", every spring, and they do quite well.

Finally, I am NOT a master gardener by any stretch of the imagination (other than wishful thinking!), and find one particular book and one particular author extremely helpful. A great general reference book is the Reader's Digest New Illustrated Guide to Gardening in Canada...have been using this for several years, and find it the most helpful of my ever expanding collection. I also like anything by Lois Hole...all her gardening advice is re Canadian gardening.

Hope this was helpful. Happy gardening!


Subject: RE: aluminum sulphate
From: Carol
Zone: 5a
Date: 25-May-02 03:23 PM EST

Hi, I am sharing this thread...I have just checked my soil for ph, it is Alkaline 8.0. I am already adding triple mix when I make my gardens or plant my shrubs and trees, is this enough to improve my soil? I have a fiddlehead fern that needs slightly acidic, I was thinking about using peat moss with my triple mix, would this be enough to change the soil to slightly acidic? Also I have some bone meal I added when planting my roses, how does this influence the soil?

Subject: RE: aluminum sulphate
From: Lee
Zone: 6a
Date: 26-May-02 10:49 AM EST

I'm also looking for info on this topic, specifically, how much aluminun sulphate do you apply around one acid loving shrub that is 2ftX2ft and you have a general soil PH of 8.1?

When I plant acid loving plants I do work peat into the soil, but in the years to come, should I be adding an aluminun sulphate, or is there something you can mix up in a liquid form that would be better?

Subject: RE: aluminum sulphate
From: Deborah
Zone: 6a
Date: 31-May-02 06:32 PM EST

Hi Carol

Slightly acid soil (about 6.5) is best for most plants. According to my favourite gardening books, you'll experience difficulty maintaining healthy plants in soil more alkaline than 8. If you want to lower your soil's alkalinity, and increase acidity, add flowers of sulfur or peat moss. Peat moss works more slowly, but improves your soil's water retention ability as well. You could also use aluminum sulphate, but as mentioned before, be careful with that, as it can build up. When you purchase flowers of sulfur at your local greenhouse, application amounts will be right there for you on the container. As for amounts of peat moss to add, I am not an exact-botanical-science gardener, so every spring, I dig in a small bucketful of peat moss mixed with lots of mushroom compost (which I LOVE!) around all my acid-preferring plants and shrubs. I do the same thing in the fall. The compost adds nutrients and helps the peat moss retain water even more, which is good for those dry, hot spells of summer. So..peat moss with your triple mix is a great idea, I think. (I can give Nova Scotians a couple of good places to purchase mushroom compost, but am not aware of suppliers in other provinces.)

Now, bone meal:this is an organic fertilizer, a by product of meat processing, a slow release source of phospherous, which helps your plants grow strong root systems; general use is 3-5 pounds per 100 square feet. I toss a handful in the planting hole whenever I plant bulbs in the fall, or transplant perennials, shrubs, etc. Roses are heavey feeders, but in the first year after planting, they should not be fed. In subsequent years, bonemeal's good, but in addition, I scratch in a commercial rose fertilizer around into the soil for extra nutrition.

Here's another "help-the-roses" hint: a friend of mine told me a couple of years ago that, in order to encourage a second blooming, she drenches the roots of each bush with 2-4 tbsp brewers yeast dissolved in 1 1/2 gallons of water immediately after the first blooming. I did this last year, with lovely results...much longer lasting roses!

Hope this was helpful!

Lee: re quantities of aluminum sulphate for one shrub: to reduce the soil pH by 0.5 to 1 point, apply 3 Tbsp dry A.S. per 10 square feet. You can also mix the A.S. with water: add 4 Tsp A.S. to 1 gallon water, and apply to 10 sq ft of soil area. Gauge the size of the soil where you have your shrub, and apply lesser amounts to smaller areas (ie dissolve 2 tsp A.S. to 1/2 gallon water for an area of 5 sq ft.) But do try large amounts of peat works more slowly, but has the added advantages of improving your soil, and no build-up!

Isn't gardening deligtful!? I'm either DOING it, reading about it, or e-chatting about it! I love this many great gardeners willing to share their expertise and secrets with others.

Thanks Donna!

Happy gardening.

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