Want to save time and money? Whether or not you are on water restrictions, water is a precious resource and the cost is rising all the time. We can all tread a little lighter on the planet by taking a few moments to re-evaluate our garden design and watering habits to eliminate inefficient practices that waste water … and reap the benefits at the same time!
How to Save Water in Your Garden
Here are my ten helpful tips for you to conserve and manage water efficiently, put money in your pocket and garden more sustainably:
1. Water Pots in the Afternoon and your Garden in the Morning – Research* shows that the timing of when you water pot plants during the day can have a significant effect on plant growth. The potted plants used in the research were grown in pine bark based potting mix (which is not only commonly used in the nursery industry, but also is a popular choice for many home gardeners.) Pine bark based potting mixes however have low moisture retention properties, meaning pot plants dry out more quickly.
The research found that plants watered after 12.00 pm and during the afternoon, “significantly outperformed plants grown with early morning irrigation.” So, watering container plants in the afternoon may lead to healthier, stronger growing plants compared to container plants watered early in the morning.
According to the University of Illinois Extension, the optimal watering time for the rest of the garden, is early morning before the temperatures begin to rise, winds are lower and there is less evaporation. Morning watering gives the plants a good supply of water to face the heat of the day.
Avoid evening watering especially on the foliage as night-time temperatures are often inadequate to dry the moisture on the leaves which can encourage some fungal pathogens to establish. However, any time plants start to show symptoms of drought stress is the time to water them – even if this means the middle of the day. Waiting too long may be too late.
2. Harvest Water – Save and reuse water wherever you can:
- Install a water tank rather than wasting rainwater, to maximise roof runoff and redirect it for use on your garden. Slimline tank and water harvesting systems are available for even the tiniest of spaces.
- Save your Cooking Water – If you steam or boil vegetables, save the water rather than tipping it down the sink! It is full of nutrients and when cooled, makes a free fertiliser for watering your plants.
- Reuse Fish Tank Water – When you clean your fish tank, use the ‘old’ nitrogen and phosphorous-rich water on your plants.
- Use a Compost System – Even micro gardeners can make compost no matter how small a space you might have. Whether you make or buy a worm farm or mini compost system, you will add a valuable water saving resource in your garden. Worm castings and compost hold moisture in your soil and help retain nutrients where they’re needed. Frugal gardeners needn’t buy a compost bin – there are many micro systems you can make yourself. I’ve made several low-cost systems that work well including converting a 60 litre black garbage bin by drilling 1cm holes on the sides and base and covering with the lid. It can be turned regularly by simply rolling it on its side!
- Bokashi - (fermented grain) bins are another efficient way to compost food scraps and add moisture to the soil. They are available commercially but if you’re a thrifty gardener you can easily make your own. All you need are a couple of buckets the same size – one fitted inside the other with holes drilled in the base of the top one to allow the liquid (fermented juice) from the scraps to drip into the base of the lower bucket. Finally, fit the lid to the top bucket. You then just dig the scraps into your garden or add to the compost and dilute the juice to use as a fertiliser.
- There are also many DIY worm farm options providing you with valuable worm castings that are pure humus and hold maximum moisture in your soil or invest in a commercial one. A mini in-situ worm farm I use is the Little Rotter – it’s compact, made from a safe plastic and adds humus where you need it (directly in your garden).
3. Choose Your Plant Container Carefully – Different materials heat up quickly or lose moisture due to porosity so think about your pot location before making a final decision. For example, metal heats up quickly so raised galvanised garden beds and metal containers will draw moisture out of the soil and these gardens will need more watering. If you live in a hot climate, this may be a major consideration. Clay pots such as unglazed terracotta also lose moisture through their porous surface and the soil will dry out faster than glazed pots. If you just have to have that metal or terracotta container, then consider using them as a cache pot (an outer decorative pot) and put a smaller less porous pot inside to retain vital moisture.
4. Mulch, Mulch, Mulch! Up to 70% of water can evaporate from the soil on a hot day if you don’t have mulch as a protective layer on top. Mulch is one of the best moisture holding strategies you can employ. It prevents evaporation from the soil surface, helps suppress water-thieving weeds from growing and many mulches add vital nutrients to the soil at the same time. Avoid fine mulches that tend to clump and become water-repellent. Instead, use a coarser mulch which allows water/rain to move down through to the soil. A depth of 3-5cm in a pot (depending on the size) and even deeper (8-10cm) in a garden bed is ideal. Apply mulch onto moist soil and water in well.
5. Reduce the Impact of Water Guzzling Plants – Species with low water needs will save you time and money in the garden. These include:
- established or slow growing plants
- small plants
- varieties with small or narrow leaves
- grey or silver foliage or
- leathery, hairy, curled or fuzzy leaves that typically require less moisture
Growing a majority of thirsty plants that suck up moisture can steal your time and money! These include:
- those with high fertiliser needs
- species with large leaves
- newly planted vegetation or
- fast growing species
Large leafed plants require and transpire more water over a larger surface area than slender leafed varieties. Leaves that reflect more of the sun’s radiation (e.g. gray or silver) usually lose water through transpiration at a lower rate than green leaves. Plants that can tolerate higher leaf temperatures also evaporate water at a lower rate. For example, herbs like small fine-leafed rosemary and thyme have minimal water needs compared to larger leafed basil and sage. Natives and succulents may make better choices than some of the more common landscape plants, so do a garden ‘audit’ and make water-wise choices.
“Remember, any newly installed plants (even natives and drought-tolerant species) need adequate water until they become established when water requirements will reduce.”
According to the College of Agriculture at the University of Arizona, “drought tolerant plants are not necessarily low water use plants and vice versa.” Some plants are drought tolerant, but are high water users when water is accessible. Drought tolerant plants become dormant when soil water is unavailable and then become active when water is available again. “Many plants not normally considered low water use species become water thrifty for survival when soil moisture is limited. Some plants considered low water use species will use water at a high rate if water is available and revert to low water use when not available.” So the message is: low water use plants won’t conserve water if they are irrigated as high water use plants!
6. Check Weather and Soils – It might seem obvious but how many times have you watered your garden, only to have it rain soon after? Turning off automatic sprinkler systems if rain is forecast is one sensible step to save money and water. Also, consider your climate, location and the season. Weather factors that impact watering include: cool temperatures, high humidity, the winter season, shade and no wind which all reduce the need for irrigation whereas hot, windy summers with low humidity will increase the need for watering. Include some tall species or garden structures that will provide more shade in your garden where possible.
Why waste water when you can check the weather online and save yourself time and money? Soils also vary with location and influence water needs – keep in mind that mulched clay soils have lower water needs than bare sandy soils.
7. Use a Moisture Meter – This inexpensive tool will help you get a feel for what each of your plants need in terms of moisture. It is easy to use and provides you with an accurate reading of the moisture content in your soil in a few seconds. 10-30% moisture indicates the soil is too DRY and you need to water; 40-70% moisture means the soil is MOIST or ‘just right’ so no action is required; and a reading of 80-100% moisture means your soil is too WET so avoid watering. Alternatively, use a screwdriver or chopstick as a soil probe to test soil moisture. If it goes in easily, don’t water; if it won’t budge then grab a watering can! A watering can is also a good way to make sure you only water as much as you need to.
8. Capture Water with Good Design – Using a variety of design principles in your garden will help you retain moisture where you need it by storing moisture in the soil and can assist run-off in areas that get too wet. Some simple principles to apply are: use plant water-loving species that suck up moisture in boggy areas or use diversion drains, swales and terraces to help intercept water flow and spread it out, so it seeps slowly into the ground where you want it rather than being lost into drains and causing erosion. Build mounds around trees and shrubs to reduce runoff and allow moisture to soak slowly into the soil around the canopy drip line and roots. Good design also applies to pruning: remove unnecessary lower branches and leaves from trees. Not only does this create a more structurally appealing tree by ‘lifting’ the eye up to the canopy, but with fewer leaves there is less moisture loss and this lowers the tree’s water requirements.
9. Increase Organic Matter – Whilst this comes naturally to most organic gardeners, many don’t realise the benefits of building humus in the soil. Organic matter absorbs many times its own weight in water, which is then available for plant growth. It provides many benefits: clay soils with added organic matter will accept water more quickly and organically amended sandy soils hold water longer, and don’t need to be watered as frequently. One of the easiest ways to build organic matter is to add compost that breaks down to humus. This has an amazing potential to hold moisture, nutrients and build soil health. It has a buffering effect against drought and plant stresses too. You can also add organic matter with worm castings; vegetable scraps; mulches like nutrient rich lucerne (also known as alfalfa) and pea straw; lawn clippings and leaves.
10. Avoid Overwatering – This bad habit increases your water bill; leaches valuable nutrients from the soil (costing you money to replace them); causes loss of oxygen in the soil pore spaces increasing the chance of root rot and other diseases from suffocation; and wastes a precious resource. Even worse, it breeds dependent plants with shallow root systems so you’ll never be able to take a holiday without returning home to a garden filled with dried arrangements!
Other Factors That Affect Plant Water Use:
- Applying fertiliser stimulates growth and increases plant water use in turf, ornamental shrubs and trees, fruits and vegetables.
- Pruning of landscape plants promotes new growth that results in higher water use.
- When plants are flowering and fruiting they have greater water needs.
- High, frequent mowing of turf increases water use by providing more leaf surface for transpiration however, this type of mowing also increases rooting depth, making the grass more drought tolerant.
10 Tips for Minimizing Plant Water Use:
- Choose native and low water use plants in your garden.
- Select smaller plants rather than larger ones.
- Reduce fertiliser use to the lowest level possible to maintain healthy plants.
- Use surface mulches around plants and in bare soil areas.
- Avoid excessive watering.
- Zone irrigation systems to water plants grouped where possible by their water use and soil type.
- Increase mowing height of lawns to allow grass to develop deeper root systems.
- Keep the lawn mower blade sharp to make cleaner cuts that cause less water loss than cuts from dull mower blades.
- Control all weeds that steal water that would otherwise be available for desirable plants.
- Be tough! Don’t waste water on unhealthy or undesirable plants – instead remove or replace them.
Learn more tips with this video on: Watering Tips for Different Sized Plants.
- Timing of Low Pressure Irrigation Affects Plant Growth and Water Utilization Efficiency
- Irrigation Timing: Effect on Plant Growth, Photosynthesis, Water-Use Efficiency and Substrate Temperature
- University of Illinois Extention – Watering Correctly Saves Time, Money & Plants
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