This week, two readers have asked me about garden problems caused by lack of water. As you know, it is extremely difficult to keep gardens well-watered in drought conditions. However, as plants can only absorb the nutrients they need for healthy growth and ripeness of crops as water-soluble ions, inadequate water is the cause of a wide range of problems, including pest attack.
Bare soil in garden beds and around trees, shrubs and vines allows a lot of soil moisture to be lost to evaporation. A 5 cm layer of organic mulch over beds and around larger plants (keeping it a hand span from the trunk) will prevent water applied to the soil from being wasted. Lawns are greedy and as their roots are close to the soil surface, they take water and nutrients intended for fruit trees and favourite ornamentals. Keep lawns beyond the outer canopy of trees and cover the area under trees with mulch.
A method that we have found very helpful to water mulched beds is to use plastic soft drink and juice bottles to funnel water through mulch directly to the root area of susceptible plants. This is a quick and very efficient way to hand water during drought, water restrictions, heat waves or windy weather. Limp tomato seedlings will freshen up in about 10 minutes after watering by this method.
Simply cut off the base of each container, remove the lids and bury the necks of the containers about 8 cm deep near outer edge of the foliage of plants. Large shrubs may require several containers. Pour water into the container until it begins to drain slowly – an indication that you have dampened the soil in the root area.
Seedlings and pot plants are usually the first to suffer during heat waves, and you can find advice on how to revive stressed pot plants here: Pot plant stress
Autumn is a good time in most Australian gardening zones for maintenance work in the garden. My kitchen herb garden needed a serious renovation after three of our chooks escaped from their run during summer and made a total mess of everything. As summer was extremely hot and dry this year, I decided not to replant until after the weather cooled and we had some decent rain. Replacement plants were kept in the shade house until weather conditions were less stressful. In the meantime, I added some compost, worm castings, poultry based fertiliser, and seaweed tea to the soil; dug out weeds and errant roots of the mint family that had strayed far beyond their allocated area; and checked the soil pH. As it was barely on the acid side of neutral, I did not need to add any dolomite.
Although we grow some culinary herbs commercially, it is a nuisance to have to wander down to the herb beds when I want a few sprigs of something for a recipe. Consequently, my husband set up the framework for a kitchen herb garden close to the house. The finished garden measures 7 metres by 4 1/4 metres.
As the ground slopes slightly, the outer border of the garden was made from bricks retrieved from a demolished wall, and second-hand pavers provide pathways for easy access to all the herbs. The bird bath in the centre provides water for birds, bees and wasps that provide pest control and pollination. The garden has a permanent border of French lavender that serves several purposes. Lavender essential oils deter garden pests and, during the cooler months, the flowers are sold to a local florist. The hedge also protects the more delicate herbs from hot winds. There is a break in the hedge on the low side of the garden to allow cold air to drain away. A solid hedge traps cold air and allows frost to form. The herb garden also provides a suitable setting for my sundial.
I like to renovate my herb garden every three or four years as the perennial herbs such as rosemary, sage, thymes and mints don’t make as much strong, tender growth as the plants age. We find we get better production from younger plants that we grow from cuttings of the old stock. When I replant annual and perennial herbs, I always change their position in the garden as these plants also require a proper crop rotation to prevent soil diseases, and my herb garden is never completely full of herbs as I leave spaces for the rotation of annual and biennial herbs each season.
The garden looks quite bare at the moment (but it is easier to see the layout). I have very recently planted chives, rosemary, lemon thyme, marjoram, oregano, spearmint, eau-de-cologne mint, sweet basil, parsley, rose geranium, French tarragon and several more common thyme plants. The lemon grass clumps and the horseradish roots survived the chook attack, as did the soapwort. (Soapwort is not a culinary herb, but I didn’t know where else to put it). Coriander and dill will be sown later this month as they both do better here during the cooler months. After planting, the garden was mulched with finely chopped organic sugar cane residue as this will break down more quickly than other mulches, and add more organic matter to keep soil healthy.
A common question asked by gardeners is how often should they water their garden.
Unfortunately, limited watering times imposed by water restrictions have encouraged some gardeners to rush around giving everything a light watering during the allocated time.
A light daily watering is one of the worst things you can do for your garden. It only encourages plant roots to stay close to the soil surface – the area that dries out first.
Plants watered in this way wilt quickly on hot, or windy, days – encouraging gardeners to perpetuate the cycle.
If you use mulch, very few plants need watering every day. Mulch not only prevents water loss through evaporation from the soil surface, it assists the capillary movement of water through soil. Seedlings will probably require daily watering through the warmer months because they have very small roots systems.
The most reliable way to decide if plants need watering, is to poke a finger, up to the first joint, into the soil or potting mix. If the soil feels damp, the plants don’t need watering. If the top centimetre or so feels dry, give the plants a thorough watering, under the mulch. When watering shrubs and trees, water under the outer edges of the mulch where the feeder roots lie, not near the trunk. Plants watered in this way develop stronger root systems, and will be more resistant to adverse climate conditions.
Many plants slow their growth or become dormant in winter, and they need less watering than in warmer months. More pot plants are killed by over-watering, than under-watering. When the surface of potting mixes feel dry, small pot plants can be watered, at any time, with water collected while waiting for the shower to warm, as long as you remove the bucket before getting in the shower and making the water soapy. Dunk the pots into the bucket until bubbles cease to rise from the water surface. Overhead watering of indoor plants can encourage fungal diseases, especially in the cooler months.