THE DIRT ON WETTING AGENTS
Here in WA, gardeners have to contend with arguably the most impoverished and non-wetting soils in the world. We trudge along, constantly topping up mulch, adding clay and applying wetting agents. Many of us grumble - it seems unfair to have to go to so much effort to have a flourishing garden - but view it as the price we have to pay for our near perfect weather for 9 months of the year.
Due to our water repellent soils, wetting agents are widely used in Perth and their use is pretty much essential if we wish to maintain a healthy garden.
WHAT IS NON WETTING SOIL?
If you are watering a plant and it puddles in the centre of the plant, or the water runs off to the side rather than down into the soil, you have non wetting soil. If your plants look sick or have died, the first port of call should be to check the soil wettability.
Soil wetters, both liquid and granular; work by improving the absorption of water, reducing the surface tension of water and helping it to spread more evenly through the soil profile. However not all wetting agents are created equal.
Here at Garden Deva, we have found liquid wetting agents to be the most effective.
Many people are unaware that the granular wetting agents must be kept wet to remain active. If the granules and the soil with which they are in contact dries out for a week or more, they become a lot less active and are rendered ineffective.
Conventional wetting agents include synthetic compounds such as petrol distillates like polyacrylamides as well as alcohol. Conversely, natural surfactants in (Certified) organic wetting agents utilise soaps, saponins, microbial agents, and organic humectants.
Most soil wetters, as well as kitchen or laundry detergents; will strip soils of goodies, kill earthworms and upset the soil biota. This is bad news for your plants and soil.
To help choose a suitable wetting agent simply check the ingredients. Look for soil conditioners like fulvic acid and seaweed, polysaccharides (natural humectants which draw moisture from the air), and natural soil surfactants (potassium soaps and saponins). These will add rather than detract from your soil.
At the time of writing this article, we have found that the only wetting agents which actually work and also improve soil microbial activity are liquids Eco Hydrate, from Organic Crop Protectants and Eco Wet from Eco Growth.
Eco hydrate contains humates and organic polymers which assist in moisture penetration and improve soil structure. It comes in a 1L container which will cover 330 sqm. You will need 3-4 capfuls per 9L watering can. For a small to average sized garden, you will usually only need one bottle per year.
Eco wet is similar in content to Eco hydrate but it is locally produced in WA. 1L will treat up to 200m2.
(Please note, GARDEN DEVA receives no remuneration for endorsing any product).
We believe that the most effective time to apply a wetting agent in Perth is in September or October and again in December or January. Apply the liquid wetting agent with a watering can, then water it in again with a hose to ensure excellent penetration. It will froth up both in the watering can and on the ground. Some gardeners like to give their soil another application in winter when it is raining.
OTHER STRATEGIES FOR SANDY SOILS.
When planting in sandy soil, it is essential to incorporate a clay amendment. These include: Sand to Soil, Soil Solver, Sand remedy and Watheroo clay. Clay based amendments make the soil more friable and help to hold on to both moisture and fertiliser, thereby saving you money and preventing our precious rivers from excess nitrogen pollution which causes algal bloom.
It goes without saying that our nutrient depleted soils need soil conditioning. Usually a ratio of between 30 and 50% soil conditioner to 70-50% soil is recommended; the amount varying depending on the quality of your soil. Soil improver may be bought in bags from garden centres or you may use your own compost or worm castings. Manure is also often added to the planting hole but we prefer to add this to the compost bin and utilise as mature compost when it’s ready.
Always thoroughly mix soil conditioner and clay amendments with the existing soil, using water to achieve a chocolate-y loam texture. Never plant straight into a hole with unmixed soil conditioner or compost. Your plant roots will burn and most likely it won’t be long before the plant dies. Other soil amendments may include kelp powder, charcoal and rock dust minerals.
Always mulch your garden. In cooler weather, keep mulch to a minimum, say 20-30mm depth. This helps to ensure adequate rain penetration in winter when your reticulation is turned off in winter. (There is a sprinkler ban in WA from June 1 – August 31st each year).
Some gardeners are surprised when they clear away their mulch after winter and discover an ailing plant which is dry due to too thick a coverage. However in summer, after applying your preferred wetting agent and ensuring your reticulation is working well, aim to have between 50-70mm for your mulch depth.
Chemical wetting agents are often used in potting mixes which is usually not the end of the world but be aware that some soil wetters can damage sensitive plants like ferns, orchids and members of the protea family (including hakeas, banksias, grevilleas and leucodendrons).
If possible, choose potting mixes containing coir peat, which is itself a moisture retentive medium.
HOW DO I KNOW IF MY POT HAS DRIED OUT?
Simply insert a dry finger deeply into the mix and you will soon feel the lack of moisture. Another indicator is that the pot will feel light to pick up or water seems to run out of the base of the pot suspiciously quickly when you water.
To remedy this, simply immerse the pot in a bucket of weak seaweed liquid (another mild soil wetter), to which you have added a liquid wetting agent. Remove the pot when the bubbles stop. In some cases, you may need to repot the plant as it may be pot bound. Take the plant out of the pot and have a look at the roots to see if you need to repot.
WATER SAVING CRYSTALS are another option for potted plants but the jury is still out on the effect of these on soil microbes and roots. Just to be sure, avoid using them with edibles. Always mix crystals in a bucket with water and add to the potting mix rather than adding dry and watering. You will find if you do the latter, the jelly like crystals will often spill over the edge of your pot.
COPYRIGHT GARDEN DEVA JUNE 2017
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