Why be waterwise in the garden?
The obvious answer is that we only have a finite amount of water and some years even less than others. Guelph relies on groundwater for its water supply which is more limited than a surface water based supply. During the spring and summer months water use increases as we spend more time outdoors watering lawn/gardens, filling swimming pools and using water for other recreational activities. This peak in outdoor water use usually happens during hot, dry times of the year when we experience little rainfall. Under severe conditions this can cause water shortages. This means we must conserve our water resources, and limit our seasonal increases in outdoor water use, to ensure the sustainability of Guelph’s water source.
By grouping plants by their water needs, and using mulch and drought tolerant plants you will be conserving on water usage.
By watering plants correctly you will also have healthier gardens and landscapes and less need to use fertilizers and pest controls. Consider that everything you do in your yard and garden will eventually effect your water source and from there, any nearby bodies of water. While you may not think the fertilizer and bug spray you use on your plants is excessive, the combined runoff from all of us is considerable.
Along with sunlight and the right soil conditions, water is essential to the success of your garden. For a healthy garden, you must make sure the plants are getting enough water without overdoing it and flooding the soil. It is difficult to give specific directions on how to water your lawn and gardens, so much depends on climate, soil type and type of plant. If landscape plants are water stressed during the summer, they may experience severe problems during the rest of the year, such as increased insect and disease susceptibility and decreased winter hardiness.
General watering tips for lawns and gardens
- Use some sort of watering gauge.
- Water once a week and apply 2.5 cm (1 inch) at the most.
- Water slowly, deeply and less often, to encourage deeper, more vigorous root growth. Always soak the soil thoroughly. A light sprinkling can often do more harm than no water at all. By watering less frequently you encourage the plant roots to search down for water, and they become stronger and better able to handle drought conditions. Watering lightly and frequently creates shallow roots that leave the plant more vulnerable to diseases and insects. There are some exceptions— new seedlings will need to be watered more frequently, and vegetables grown in very sandy soil may prefer smaller amounts of water spread throughout the week.
- Avoid over watering which does more than deplete the water supply, it also makes plants prone to pests and adds to storm water runoff, which pollutes our water systems. Watering correctly can reduce water bills, insect and disease problems, and maintenance requirements. For example, the more you water your lawn, the faster it grows and the more it needs to be mowed.
- The best time of day to water your gardens and lawn is first thing in the morning before the heat of the sun causes too much evaporation. Water the roots of the plants and not the leaves. If you water at night when the day is cooling off, the water is likely to stay on the foliage, increasing the danger of disease. Watering before 9 a.m. is the best time when loss to evaporation will be at a minimum. As an alternative you can water in the evening, but the residual dampness left on leaves and the soil surface may attract pests such as slugs and earwigs, as well as making ideal conditions for diseases.
- Use the right kind of sprinkler. Sprinklers that shoot low to the ground are far superior to the oscillating fan type of sprinklers that lose much of their water to evaporation and wind drift before it ever hits the lawn.
- Use a watering can whenever possible instead of a hose. If you do use a hose, use a trigger to control the flow. Hand watering is more water efficient, as you have total control over where the water is applied. If you use manual sprinklers, consider purchasing garden tap timers.
- Examine the soil in your garden to see if it is too dry and crumbly, or where it’s too wet and muddy. Checking the soil often will help you avoid both over watering and under watering.
- Take special care of plants in containers—they run out of water more quickly than established plants that have bigger root systems and more soil from which to collect water.
- All new plantings need to be watered for at least 3–4 weeks, until the roots are well established and can look after the plants water up-take needs. Water thoroughly when you do. Even if it rains check to see that the soil is wet to at least 2.5 cm down. Mulch plants to retain moisture and to keep weeds down
Guelph’s Outside Water Use Program doesn’t restrict tree, shrub, flower or garden watering during Level 0 Blue and Level 1 Yellow conditions, and allows for alternate day and time watering restrictions during Level 2 Red.
Give ’em a drink of rainwater
Rain barrels are an excellent way to capture rainwater for use in the garden. Plants much prefer the rainwater as it is soft and warm in temperature. Place a rain barrel at the downspouts of your eaves troughs to collect rainwater to use on your lawn and garden. Make sure the rain barrel has a screened lid, childproof top, overflow mechanism and hose attachment for watering. Rain barrels are available to purchase from local stores such as home improvement, hardware retailers and garden centres. Water Services holds an annual truckload rain barrel sale every spring. Please contact Water Services for more details at 519-837-5627 or by email firstname.lastname@example.org.
Watering your lawn
Grass grows best in spring and fall when there’s more rain and the temperatures are cooler. During the hottest summer months, your lawn may begin a dormancy phase and turn brown. This is your lawn’s natural response to stress, evolved overtime as a survival mechanism in response to stress. When the temperatures get hot and rain is rare, your best option is to let your lawn naturally slow its own growth. In fact, it’s best to let your lawn go dormant during dry periods, and the City’s Outside Water Use program does not allow any lawn watering when in Level 2 Red.
Here are some tips to help you water your lawn wisely, and save you time and money.
Know when it’s time to water
When the weather suddenly turns warm for a few days, most people feel the need to water their lawn, but your lawn probably doesn’t need watering yet. In fact, subjecting your lawn to mild drought stress will increase rooting and make your lawn stronger and healthier if a drought does occur. To check if your lawn really needs water, take a walk across it. If the grass bounces back up after your steps, it’s ok; if your footprints stay imprinted on the grass, it may be time to water. Grasses also tend to turn darker in colour as they enter drought stress.
Use the right amount of water
Your lawn only needs about 2.5 cm (1 inch) of water per week, and that includes rain water. If it hasn’t rained for an extended period, you may choose to water your lawn yourself. Be sure to check what the current watering restrictions are and make sure you only water when you’re permitted,
Use a sprinkler that shoots low to the ground to avoid losing precious drops to wind and evaporation. Use a rain gauge or a tuna can to measure the water and stop when it reaches 2.5cm or fills a little over half of the tuna can. If you time this you’ll know exactly how long to set the sprinkler out next time.
Water where it’s needed
Make sure to aim your sprinkler onto areas needing water too, not driveways or sidewalks where unsuspecting passersby may get an unexpected and unwanted cold shower!
Target problem areas by watering them by hand. Many lawns have one or two spots that require more water than the rest of the lawn, such as a south-facing or sunny area in an otherwise shady lawn. If you water your entire lawn every time you need to water these hot spots, you’ll likely overwater other areas of your lawn and may create unwanted disease or pest problems.
When it’s dry, mow high
Mow your lawn at a higher than normal height. This will help shade the soil, stop weeds from getting started, and encourage deeper grass roots. If your lawn has gone dormant, stop mowing altogether.
Dormant is not dead
Guelph’s Outside Water Use Program does not allow lawn watering when the city is under Level 2 Red watering restrictions. When conditions turn hot and dry, your best action if to let your lawn go dormant. Switching back and forth from watering to drying out is more harmful to your lawn’s health than just stopping watering all together. If your lawn goes dormant, reviving it with a large watering will drain large amounts of nutrients from your lawn and potentially cause it to die. A healthy lawn can survive several weeks in a dormant state.
Avoid fertilizing during a drought
Good fertilization typically requires watering. During a drought, you may not be allowed to water depending on the City’s water use restrictions. Even if it’s okay to water, or if heavy rains are expected, when the ground is dry, water—and your fertilizer—will probably run right off your lawn and into the stormwater drains. This is a waste of money for you, and it washes chemicals straight into our local rivers. If you must fertilize, and it’s okay to water according to the Outside Water Use program, use a very light watering to give your fertilizer the opportunity to be absorbed by your soil.
Don’t let thatch build up
Excess thatch can prevent water from getting where it needs to go—your grass’s roots. If thatch is more than 1.2 cm (1/2 inch) thick, dethatch your lawn with a heavy rake or dethatching tools. Proper mowing, watering and fertilization can reduce the build-up of thatch, while overwatering and over-fertilizing can increase it.
Limit how much you walk on a dormant lawn
Dormant grass is already stressed, and foot traffic or landscape equipment will crush the dry, delicate crowns of the grass. This will kill the grass and cause bare spots in the lawn where weeds can invade. Don’t mow your grass when it’s dormant.
The amount of water added to your gardens will be based on the type of species present. Grouping your plants according to the amount of water they need will reduce any excess watering. If you have a favourite plant that needs extra water, plant it near your rain barrel or hose. This way, you will not have to walk far for watering.
Watering drought resistant plants, deeply, once a week for the first 3-4 weeks will help them get established. Once they are established, water only when needed. If there has been an extended time without any rain, you may want to add supplementary water for your plants. It is normal for your plants to look wilted on a hot summer afternoon. This is a natural adaptation to the heat. Once it cools off at night, the plants will perk up again. If your plants are wilted at night, then they need a deep soak.
The best time of day to water your gardens is first thing in the morning. Watering at night is an alternative, but make the effort to ensure the water is added to the soil, not onto leaves and stems. Wet leaves and stems make an ideal environment for pests such as slugs and earwigs, as well as moisture loving plant diseases and fungi.
Soaker hoses and drip irrigation
If possible, avoid watering your gardens with an over fan-type sprinkler. Soaker hoses or drip irrigation systems are much more efficient watering methods, as they direct the water right to the root system, at a slow pace so that the soil can absorb it all. A soaker hose is basically a garden hose with holes punctured in it, which can be snaked around the base of your plants, providing a slow, steady source of water. Drip irrigation is comprised of main lines and emitter lines which run straight down the rows of your vegetable garden. You can plan your own drip system, or buy a pre-packaged kit designed especially for vegetable garden irrigation. Not only is less water lost to evaporation and runoff, but foliage wetting and the resulting spread of disease is prevented.
New plants, especially trees, with their relatively small root systems, do not have the capacity to take up water as quickly as they need, but will be encouraged to grow their roots out and down by infrequent soakings. “Tough love” makes for strong plants.
Water close to the ground to efficiently water the plant’s roots. Spraying plants from above creates leaf wetness which contributes to diseases and leaf scorch.
Water slowly, deeply, and less often to encourage deeper, more vigorous root growth. Always soak the soil thoroughly. By watering less frequently you encourage the plant’s roots to grow longer in search of water, and they become stronger and better able to handle drought conditions. Watering lightly and frequently creates shallow roots that leave the plant more vulnerable to disease and insects.
There are some exceptions – young or new plantings require more moisture at the soil’s surface to help their roots get established.
Use a watering can whenever possible. Hand watering is more water efficient, as you can control where the water is applied.
Soaker hoses are a great way to get water to the roots of plants, especially in a vegetable garden. Soaker hoses can be connected to rain barrels and used when needed.
Put the right plant in the right spot
If plants are healthy and in the correct location for sun/shade, they will be able to withstand some drought conditions. A plant that is established will wilt in the afternoon sun, but will be fine in the morning. This does not mean the plant needs to be watered. Plants that have been in your garden for more than 2 years, should be able to withstand some drought conditions. Only water newly planted plants and usually just for the first year, keep an eye on them the second year and after that they should be fine.
Vegetable garden watering
Most vegetables need some watering to reach their full potential. However, with a few simple practices, the water needs of your vegetable garden can be greatly reduced. Similar to your established lawn and flower gardens, 1 inch (2.5 cm) of water per week is generally sufficient. Use a rain gauge to keep track of how much rain has fallen during the week, and provide additional water only as necessary. Water more deeply but less frequently (1 inch, 1 or 2 days per week) to encourage deeper, more vigorous root growth. There are some exceptions—new seedlings will need to be watered more frequently, and vegetables grown in very sandy soil may prefer smaller amounts of water spread throughout the week.
You can time your watering to when the plants need it most in their life cycle. For soft fruits and vegetables such as tomatoes, they require a little extra water while their fruit is setting. For leafy vegetables, more water is needed as their hearts develop; for peas and beans, add water when they are flowering, and for potatoes, when the tubers begin to form.
Group your vegetables and herbs according to their moisture needs. Don’t waste water on herbs such as rosemary, sage, oregano, winter savoury, and thyme, whose flavour is actually improved if grown in hot, dry conditions similar to those in their native countries. Perennial vegetables such as asparagus and rhubarb do not need frequent watering.
Some additional tips for vegetable watering
Cut the top from gallon-size milk jugs, punch very small holes in the bottoms, and set them in the ground with only the neck showing above the surface. Use one jug near each large plant (such as tomatoes, cucumbers, or squash) and fill it once or twice a week. This will direct water towards the roots more efficiently.
For maximum water penetration, prepare a flat soil surface. Raised areas such as hills dry out more quickly, and water runs away from the root zone and is wasted.
Container planting of vegetables will use more water than in-ground gardening. Containers dry much faster than garden beds and rows.
Tree and Shrub Watering
Trees and shrubs whether established or newly planted have certain water requirements that they need to survive. During drought conditions, trees should be given a higher priority than lawns. Lawns can be replaced in a matter of months whereas a 20 year old tree will take 20 years to replace.
Newly planted trees (less than three years old) can become distressed from hot, dry weather. The City of Guelph urges residents to water any newly planted tree that is close to your home or place of business during the summer. Just 20 litres (5 gallons) of water on a regular basis—that’s a pail of water or two minutes with a garden hose—will help preserve our natural resource.
What a tree under “drought stress” looks like
- Symptoms of drought injury to trees can be sudden or may take up to two years to be revealed. Drought injury symptoms on tree leaves include wilting, curling at the edges, and yellowing.
- Deciduous leaves may develop scorch, brown outside edges or browning between veins.
- Evergreen needles may turn yellow, red or purple. They may also turn brown at the tips of the needles and browning may progress through the needle towards the twig.
- In continued drought, leaves may be smaller than normal, drop prematurely or remain attached to the tree even though brown.
- Often times, drought stress may not kill a tree outright, but set it up for more serious secondary insect and disease infestations in following years. Deep watering to a depth of 30 cm (12 in.) inches below the soil surface is recommended.
How to water trees and shrubs
- Saturate the soil around the tree within the “dripline” (the outer edges of the tree’s branches) and about 30-60 cm beyond the dripline to disperse water down toward the roots.
- The objective is to water slowly, dispersing the flow of water to get the water deep down to the trees roots. Watering for short periods of time only encourages shallow rooting which can lead to more drought damage.
- Don’t dig holes in the ground in an effort to water deeply. This dries out roots even more. A soil needle/deep root feeder attached to a hose is acceptable to insert into the ground if your soil is not too hard and compact.
- Overhead spraying of tree leaves is inefficient and should be avoided. Watering at ground level to avoid throwing water in the air is more efficient.
Do not fertilize a tree that is under drought stress
Salts in fertilizer may burn roots when there is not sufficient water. Fertilizers may also stimulate top growth resulting in too much leaf area on the plant for the root system to maintain during periods of limited soil moisture.
Newly planted trees
Newly planted trees require a regular supply of water to survive since they have not yet established a fine network of roots and are less able to absorb water. For this reason, it is necessary to actively maintain moisture in the soil surrounding the newly planted root ball. This can be achieved by watering the hole before planting and through regular, slow, deep watering.
The most common reason for the poor survival of new trees is inconsistent watering. Several hours of rainfall is ideal but can’t be relied upon each week. During dry periods, use a soaker or drip hose for supplemental watering. The best way to ensure that the water applied to the tree actually penetrates the root ball is to maintain an earth ring or saucer around the tree. Place the hose in the saucer and water for two hours twice a week. During a week when it rains two or more days, watering is not necessary. Watering should continue until the first frost with one final soaking in late fall to get your tree through the winter.
A tree that has been planted for 15 years or more may appear to be able to fend for itself under any conditions. At this point in a tree’s development, its root system has spread out away from the trunk and can reach water and nutrients even when surface conditions appear very dry. However, during extended drought periods, the remaining soil moisture is so tightly held to the soil particles that a tree’s roots cannot use it. Trees of all ages suffer when extended drought conditions are experienced. Water stress happens very quickly for trees planted in difficult areas such as sidewalks, patios, or raised lawns where water naturally drains away. As with humans, stress can make an otherwise healthy tree more susceptible to pathogens looking for weakness. Extra water to all trees during a drought, regardless of age, can keep defences strong against invading insects or disease.
Take special care of plants in containers – they run out of water more quickly than established plants that have bigger root systems and more soil from which to collect water.
Make sure your containers are not hidden under overhangs that prevent them from receiving rainfall.
Clay and wood containers wick moisture from the soil. Use plastic liners inside decorative containers to provide moisture retention.
It is more difficult to re-moisten dry soil than it is to keep it moist, water containers frequently enough to prevent the soil from drying out too much. Make sure your containers have adequate drainage holes. Most plants grow best in soil that remains evenly moist without becoming soggy. Excess water contributes to root rot problems.
Use mulch in containers. Mulch the exposed soil in containers to help prevent water evaporating. Using bark nuggets, straw or another organic mulch keeps the moisture in the soil where it belongs.