Grey Leaved Plants, Dry Soil and Water
The grey leaves on plants are covered in small upright hairs that trap moisture next to the leaf thereby reducing the amount of water the leaf loses. A leaf will evaporate water from its surface as it gets swept by any breeze, which sucks the water away from the leaf. By having a ‘forest of hairs’ a physical barrier retains water next to the leaf surface.
Grey leaved plants are often found in very dry places, like a desert, so they need to trap any available water as there is no indication when the next lot of water will arrive. When I was a Jackeroo in Far Western Queensland, west of Quilpie, I experienced only 6 inches (150 mm) in 6 years with sometimes half an inch (12mm), then nothing for another 2 months. In this climate, all the native plants were grey leaved, including many in people’s gardens, as experience had taught the owners that grey leaved plants survive dry conditions.
I often tell people that very dry sand repels water. If you put a drop of water onto dry sand at the back of the beach, the water will just sit there. BUT if the sand is even slightly moist, the water will immediately go down into the sand.
Exactly the same situation occurs with garden soil or potted soil that has dried out. The dry soil will repel the water. In a pot of dry soil, the potting mix will shrink away from the side of the pot so when water is applied the water comes straight out the bottom BUT the potting mix is still dry.
For those people with a Compot, the contents of the Pot will be moist, including the surrounding soil as moisture is constantly leaching out (assuming you are continuing to feed your Pot). So you will not have super dry soil to try and re-wet.
If you have super dry soil you can help to re-wet it by applying a wetting agent. In most cases you can use a small amount of washing up liquid mixed in with the water to wet the potting mix or soil in your garden. This will break down the water surface tension letting the soil or potting mix take in some water
Of courses it is far better to avoid super dry soil by using your Compot as this will keep the surrounding soil moist, especially if you top-up your Compot with kitchen scraps that have coffee or tea water added to it from the container beside your sink just as I do, and let the hundreds of unpaid worker worms take the broken down material away for you free of charge.
And remember to cover your soil with straw, hay, leaves, mulch, grass clippings or whatever to help retain moisture and plant grey leaved plants that don’t require much watering such as Lavender, Salvia argentea (Silver Sage), Echeveris, or Kalanchoe Beharensis
Today’s Did You Know…?
It is a lot better to have water applied to soil or pots with a light watering application. When conditions become dry, and we then get rain, it usually comes in a heavy downpour all at once. The water simply runs off the dry soil taking a lot of topsoil with it while very little will actually penetrate below the surface soil.
The same applies when you are watering pots or garden soil. It is better to apply the water gently so that it penetrates below the surface, but also to water a lot at once, but at longer intervals. With water penetrating deep into the soil the plant roots will go deeper to seek out the water rather than staying in the topsoil where the soil dries out faster. This way you will obtain a greater benefit from your watering, use less water in total and lower your water bills. A Win Win situation.