Don't forget your hat and gloves!
WHY DO PLANTS NEED WATERING?
Plants release a mist of water through special holes in their leaves when the air around them is dry. Doing this creates a vacuum inside plants that sucks water from the soil through the roots into the plants to replace the water lost through the leaves. Plants can open or close these special holes to adjust the amount of water that is released. This process is called 'transpiration'. In very hot weather, plants release a lot of water through their leaves to keep cool, rather like the way our skin sweats on hot days. In very windy weather plants also lose a lot of water because the water they release gets blown away.
If there is not enough water in garden soil to replace the water released into the air, the softer cells of plants collapse and the plants wilt. Small plants may not recover if they become very wilted, and may die.
Plants that do not have enough water become water-stressed. Stressed plants send out smells that encourage pests to attack them. Water stress also weakens plants' defence systems so that they are unable to resist diseases, just like people become sick if they are very stressed. Nature designed plants that way because nature wants only the strongest and healthiest plants to grow to maturity and produce seed. One of nature's basic rules for both the plant and animal kingdoms is 'survival of the fittest'.
Water stress is common in areas of our country that have long periods with very little rain, or without any rain at all. During periods of drought, water levels in storage dams and water tanks become very low. To prevent us from running out of water for drinking, cooking and washing, rules are set to limit how often gardens can be watered, and there is even less water to spare for plants! However, you don't have to use a lot of water in your garden to keep plants healthy. Today's lesson is about some ways that you can keep plants healthy while saving water in the garden, too.
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HOW TO SAVE WATER IN YOUR GARDEN
• The best thing you can do to save water in your garden is to make sure you keep some compost in the topsoil of your garden beds. As you learnt in Lesson 3, humus in compost is like a giant sponge in the soil. Humus holds water near the plant roots so that it doesn't drain away, and plants will need watering less often.
• Seedlings in garden beds and pots will probably need watering every day through the warmer months because they have very small roots that are close to the soil surface. Seedlings can be watered with a watering can so that you don't waste water.
• Always water seedlings first, then any other young plants in garden beds. Then give larger plants and any fruit trees a deep watering only when they need it. Plants watered in this way develop stronger root systems, and will be more resistant to dry or windy conditions.
• When watering large plants and fruit trees, water under the outside edges of the leafy area where the feeder roots lie, and not near the trunk.
• Water your plants early in the day in cool weather, and only if they need it. Many plants grow more slowly in cooler months and don't need watering very often then.
Water in garden hoses gets hot very quickly on sunny mornings and can reach temperatures that are far too hot to shower under! Remember to put garden hoses in a shady spot immediately after watering.
Always allow a small quantity of water to run through the hose before using the hose to water pots or garden beds. There are three reasons for doing this.
• It will let you check that the water coming from the hose nozzle is cool and will not burn your plants
• It will flush out any chemicals that can transfer from the plastic hose into water lying in hoses
• It will let you adjust the nozzle to a gentle flow in case the last person that used the hose left it set to full blast.
Don't use sprinklers to water your garden because a lot of water will evaporate into the air, and your plants will not get as much water as you think. Sprinklers wet leaves too, and this can encourage mildew diseases if the leaves of stressed plants can't dry quickly.
After your plants have grown up and become stronger, watering all of your garden every day is not good for plants, because most of the time you can only manage to wet the top centimetre or so of soil – the part of garden soil that dries out first. If only the top centimetre of soil is dampened when watering, plant roots are encouraged to stay very close to the soil surface and plants will wilt quickly on hot or windy days.
Don't water plants in the middle of the day in hot weather, because water droplets on leaves are like tiny magnifying glasses. Strong sunlight is concentrated through the droplets and can scorch the leaves of plants.
Dripping taps waste lots of water! Always make sure taps are fully turned off when you have finished using them.
WATER FOR WILDLIFE
Birds, frogs and lizards that eat insects, wasps that lay eggs in insect pests, and bees and wasps that pollinate plants all need water, too. When we try to save water in the garden, there is often not anywhere for these helpful visitors to get a drink. Perhaps you could include a birdbath near your garden area. A deep plant saucer filled with clean water will do if it is placed above ground where birds feel safe. A deep plant saucer filled with water in a cool, shady spot near your garden will make frogs and lizards feel welcome, too.
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MULCH YOUR GARDEN
You may have noticed that wherever you disturb soil, tiny plants will start to grow. This is because the soil contains lots of weed seeds and nature hates bare soil.
Bare soil allows a lot of water to evaporate in hot and windy weather. As soil dries out, organic matter breaks down very quickly and precious carbon is lost from the soil. Helpful soil organisms die when soil is dry and contains no food left for them to eat. Dry topsoil is blown far away in dust storm clouds when strong winds occur, or it is easily washed away in heavy rain, causing soil erosion.
Nature tries to prevent this damage by using whatever seeds are in the soil to protect the soil surface. The leaves of weeds shade the soil surface from hot sun so that it doesn't dry out quickly, and the roots of weeds hold the topsoil together and stop it from washing away in heavy rain.
You don't want a garden full of weeds, so how can you protect your garden soil?
Some farmers use the remains of old crops or grow green manures to protect their soil, but the fastest way for gardeners to protect their soil is to put mulch on garden beds.
Mulch saves water! Mulch stops water evaporating from the soil surface on hot days and helps water to spread through soil so that the water you put on your garden will cover a wider area. Mulch helps humus keep soil damp, and your plants will need watering less often.
Mulch provides a sunshade for earthworms, and all the helpful bacteria and fungi in your topsoil. They need damp humus and soil to live and work in. Mulch also helps keep soil cooler in summer and warmer in winter.
Organic mulches are the best for your garden. Soil creatures break them down to add more humus to your soil. Mulch hay, straw, sugar cane residue, organic-allowed mushroom compost lemongrass tops, wilted grass clippings, green manures, and well-rotted animal manures. Mulch hay, straw, and shredded sugar cane are supplied in tightly packed bales of smaller pads of mulch material.
If you put mulch on beds too thickly or in tightly packed
pads, the mulch will be like a thatched roof that keeps ALL the rain out.
Organic mulches should be teased out or fluffed up before putting them on garden beds or around trees and shrubs.
A layer of teased-out mulch 5 cm thick allows rain to trickle through to the soil while still stopping humus and topsoil from washing away in heavy rain. It keeps soil cool enough for earthworms and microorganisms, and keeps the soil surface dark so that weed seeds won't germinate. When compost is used as mulch, it still needs to be covered with a 2-3 cm layer of hay or grass clippings or the living microorganisms in compost will die if they are left uncovered on the soil surface.
Put mulch on your garden after watering or rain, and always keep mulch 10 cm away from the stems of larger plants. The best time to mulch beds is after you get them ready for planting so that earthworms and helpful bacteria can get working on the organic matter dug into the bed. Water your garden under the mulch, as watering through mulch takes a long time.
To make watering larger plants under mulch easier, you can use large plastic drink bottles (recycling codes 2 or 5) with the cap and base removed. Bury the neck of each bottle about 6 cm into the topsoil near the outside edge of the plant leaves (see photo). Water the plant by filling the bottle. If the water drains quickly, keep filling the bottle until it drains out slowly. This method will help you to water plants quickly without wasting water, as water will go straight to the root area where it is needed.
In vegetable gardens where some plants need frequent watering or extra plant food, fluffed-up 'sausages' of organic mulch between rows of plants make watering easier.
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