Saving water in the garden – Polyacrylamide crystals

Watering a garden can be a very wasteful affair, particularly in areas of high evaporation where plants not suited to drought prone climates are grown. While switching to drought tolerant plants is certainly advisable, it’s not always practical or possible in the short term – and that’s where polymer crystals can be of benefit. Even drought tolerant plants can benefit from the use of water saver crystals.

These special crystals can absorb up to 50 times their own weight in water according to manufacturers (some claim 500x), forming a gel and then slowly releasing water as the plant requires it. This can reduce watering frequency by up to 50%, improve soil aeration and reduce the leaching of nutrients and fertilizers.

The crystals have a useable life of up to 5 years and are biodegradable; eventually breaking down into water, carbon dioxide and nitrogen – all of which can be used by the plant. During their useful life-cycle they can be dried out and be rehydrated many times.

The crystals are manufactured under many brand names and also included in some all-in-one fertilizers; where they may be referred to as “wetting agents”. Depending upon the brand and quality, 2 teaspoons of the crystals will absorb up to a litre (quart) of water.

Polymer crystals are being used in all sorts of cultivation applications; from the home gardener through to large scale agriculture. I used a product containing the crystals when carrying out a revegetation project in a semi-arid area of Australia. While I didn’t have a control group to compare results; the survival rates of the native seedlings assisted by the wetting agent was quite impressive given the very dry conditions at the time.

Polyacrylamide crystals work best when placed below the plant at the point of planting rather than on top or dug in around existing plants. Exposure to sunlight will reduce their efficiency.

The granules are clear or white, odorless and come in a variety of sizes – the smaller sizes more suited to sandy conditions and the larger granules mostly used in heavy clay soils. Florists also use the crystals as a dirt and splash free way of preserving cut flowers.

Polymer crystals are made from the same substance used in disposable diaper linings, polyacrilamide. As with all things synthetic, there do appear to be some risks. Polyacrylamide is not toxic, but unpolymerized acrylamide may also be present in the finished product if proper quality controls have not been observed. Acrylamide is a toxic substance, a cumulative neurotoxin and thought also to be a carcinogen; so it’s best to only purchase from a trusted supplier and handle the granules with care – wear gloves and a mask.

If you’re looking for suppliers in your local area or to purchase online; try searching on the following terms:

polymer crystals
water saving crystals
Polyacrylamide crystals

Availability seems to be pretty much worldwide, but prices do vary widely – expect to pay anywhere from USD$9 – $14 a pound. You can save substantially (up to 50%) by buying it in bulk; so if you have neighbors into gardening, perhaps pool your resources and save not only a stack of water, but a bundle of cash too!