Watering seems like it would be really easy. Just turn on the hose until things are wet, then stop. But watering is actually a bit more nuanced than that. Paying close attention and watering optimally can bring your garden to the next level.
Earlier this year we discussed soil type. Knowing your soil type helps choose soil amendments and plants that will thrive in your garden, and understanding your soil type will also help you water better. If you have well-draining soil, you might have to water more often than if you had a clay-heavy soil. If your soil has a lot of clay, you might want to water more slowly to allow the water to soak in, rather than run off. To read more about soil type and amendment, you can click here.
To water well, it helps to know your plants. If you’re planting a new garden, try to put plants with similar water requirements together. If you plant a little bog plant that likes constantly moist soil next to a drought loving desert plant, one or both of them will be very unhappy. If you want both of these types of plants, plant them in different areas so you can cater to their separate water needs.
As a general rule, plants do better with less frequent, deep watering. This encourages them to send their roots down deeper. Deep roots allow them to get water more consistently, so they won’t be as susceptible to variations in temperature and humidity. For most plants it’s ok/good to allow the top couple inches of soil to dry out completely before watering again. When you do water, make sure the water is really soaking down to the roots. You can test this by digging a small hole near your plants (careful not to damage the roots), to see how deep the water penetrated in relation to the roots. If plants are in small enough pots, lift the containers to feel the difference between wet soil and dry soil. Also take note of the difference in soil color. Wet soil is darker than dry soil. Use all these cues to help you determine the next time the garden needs water.
Apply water slowly to allow the soil to absorb it as much as possible. Too much water too quickly will cause the water to run off and not end up where it needs to be. Using a drip irrigation system, a gentle rain watering can, a soaker bulb hose attachment, or adjusting the gallons per minute on your sprinkler system will help you achieve this with whatever watering system you’re using.
Watering early in the morning is usually the best. This allows the water to soak into the ground instead of evaporating immediately. It also usually means the area around the plants is dry enough by night time to avoid promoting fungal diseases. A timer on an automatic watering system can help you water at the right time AND you won't have to get out of bed at 5am.
Most plants don’t like getting their crown or leaves wet. For this reason, avoid overhead watering if possible. If you have no choice but to water over the plant, it becomes especially important to water at the right time of day to avoid sunburn (water drops can work like little magnifying glasses), and to avoid wetness overnight (promotes disease). In fact, some pests can be deterred from your garden by periodically spraying down plants with a high powered hose (especially mites and aphids).
If you are using a hand held watering can or a drip irrigation system, it’s best to get good water coverage. If you only wet a small spot near the plant, it can stress the plant. Plants prefer more even moisture all the way through the root zone.
Unless you have planted bog plants, it is best to avoid completely saturating the soil. Plant roots still need air, and unless they are adapted otherwise, they will die if kept underwater for too long. Set timers on your irrigation system so you don’t forget to turn it off. Many automatic sprinkler systems are available with moisture sensors as well, so your watering system won't turn itself on when it is raining.
On the other hand, drought tolerant plants often need to be well established before they are truly drought tolerant. These plants often have deep roots that help them get the water they need, even in dry conditions. But they will still need water while they are getting established. Help them grow deep roots by gradually spacing out the time between watering, allowing them to go longer and longer between each watering. Many long lived drought tolerant plants will eventually stop needing supplemental water except in very hot and dry conditions. Drought-adapted plants are usually very sensitive to water on their leaves, so try not to get the plants themselves wet while watering.
If something is wrong with your plants, the water situation is a good place to start troubleshooting. Over watering and under watering symptoms are pretty similar. In both cases plants will wilt, turn yellow, and eventually die. To determine which extreme is the problem, check the soil. If the plant is wilted but the soil is soaking, you are over watering it. If the plant is wilting and the soil is dry, you are under watering it. You can also take a peek at the leaves that are turning bad. They will often yellow in both situations. If it’s over watering, they will be mushy and usually smell rotten. If under watering is the culprit, they will often be crispy and dried out.
Lastly, pay attention to the weather and surrounding environment. You will need to water more when it is hot and dry, less when it is cold. Don’t water at all if it’s rainy. Shady areas will be slower to dry out than very sunny ones. Wind dries out plants and soil very quickly. Taking all this into consideration, your watering routine should change with the seasons and the weather.
This all sounds like a lot, but all you really need to do is pay attention and you will notice the trends of your area and your garden. Finding the solution that makes your particular plants in your particular garden happy can be the most satisfying part of gardening. It will take some trial, error, and repetition to get it right, and that’s ok. It is truly the only way to learn this deceptively difficult skill. Don’t stress too much, getting it most of the way right is usually good enough.
Enjoy your well-watered garden!