Of all the tasks that come with maintaining a garden, watering seems like it would be a no-brainer — you just aim a hose and spray, right? But inconsistency in watering is often a prime factor in plant failures, so let's take a look at the how, what, and when of watering your plants properly.
How Much Water Do Plants Need?
This simple question leads to several answers, most of which hinge on the type of plants you're growing and what kind of garden you have.
As a general rule:
- Container plants need the most water and more frequent application, as moisture tends to evaporate quicker. Smaller containers need daily or twice-daily watering, especially in high summer.
- Raised beds need moderate amounts of water, and can live with less if they're well mulched. A good soaking once (up to three times) a week should suffice for most raised beds.
- In-ground gardens need the least amount of water, provided the soil is properly amended. Thoroughly water once or twice a week for established plants.
Assuming you have good, loamy soil that retains moisture but drains well, conventional wisdom says plants need approximately 1 inch of water per week, including rainfall and irrigation.
However, many variables exist such as the time of year, the weather conditions in your zone, the size of your containers or beds, the amount of sun or shade your plants receive, the age of your plants and even their state of dormancy or activity. So there is no easy answer to, "How much water do plants need?"
The best answer is: Give them as much as they need.
A simple trick to determine whether your plants have enough water is to use the finger test: stick your finger in the soil (or dig a small hole) and feel how moist it is. If the first 3 to 4 inches of soil seems dry, water the plants slowly but thoroughly, directing the water right at their roots.
You can also use a moisture meter (found at garden supply stores) to check the amount of moisture in the soil.
What Types of Irrigation Methods Are Available?
Irrigation can be manual (where you must remember to water when needed) or automatic (where your irrigation system is set on a timer and scheduled to run at certain intervals throughout the week). If you travel frequently or struggle to water consistently, you may find that an automatic irrigation system is a worthy investment.
Most people start off watering by hand, either with a watering can or a garden hose, and that's often all you need. This lo-fi setup is perfectly suitable for small gardens, container gardens, hard-to-reach beds or spaces, new or delicate plantings, and gardeners who are able to devote a lot of time to their plants.
Watering cans come in a range of capacities, but a 2-gallon container with a classic sprinkler head is the most versatile for outdoor use.
Garden hoses should be fitted with a gentle spray or shower nozzle. If you have hanging baskets or other high planters, consider a long-reach watering wand for easier access.
A soaker hose looks similar to a garden hose, but it's made to seep water along its entire length through tiny pores in the material. Soaker hoses are ideal for in-ground gardens, as they can be snaked in between plants and buried under mulch, lending a neat appearance to the landscape. They're very efficient as they deliver droplets of water right on the ground, no faster than the soil can absorb it, thereby reducing any chance of runoff or waste. Soaker hoses can be connected to a faucet with a garden hose, and then attached to a timer for hands-free watering.
Drip lines take the idea of soaker hoses several steps further, and make for the most precise means of watering your garden. Through a network of tubing, valves, bubblers, sprayers, and emitters, drip lines can irrigate everything from small pots of flowers to large rows of vegetables, and even jump from bed to bed without any water waste. The system drips water at a set rate right along the base of your plants, and can be connected to an irrigation timer. While drip lines are the most labor-intensive to install, they can be fully customized for every size, type, and shape of garden.
For large, flat areas, sprinklers are an easy and economical option. They can be used to irrigate lawns and groundcovers, newly seeded gardens, and newly emerged seedlings. If you choose a sprinkler with an adjustable spray pattern, you can dial in the range to more effectively water your garden without runoff. The drawback to sprinklers is that moisture is often lost to wind drift or evaporation, and only 40% of the water actually reaches the root zone of plants since much of it stays on the leaves. They're fine for low-growing bedding plants, but not practical for large plants or food crops.
Watering Dos and Don'ts
- Do group plants with similar water needs together in the same bed.
- Do check your plants often until you're familiar with how much water they drink and when you need to water them.
- Do water early in the morning (before 10 am) so leaves have a chance to dry before sundown.
- Do water right at the roots, where plants need it most.
- Do water deeply and thoroughly so that the first 3 to 4 inches of soil stays moist.
- Do water slowly, particularly for containers, as you want to give the soil time to absorb all the water before it runs out the bottom.
- Don't water shallowly, as it discourages plants from developing deep, strong roots.
- Don't water vegetable crops from overhead, as lingering moisture on the leaves can lead to pests and diseases.
- Don't forget to adjust the timer on your irrigation system every season, or during periods of drought, heat, rain, or cold.
- Don't neglect your faucets, hoses, and lines, which can wear down and spring leaks over time.
Expert Tip: Save water by mulching your plants. No matter which irrigation method you go with, adding 2 to 4 inches of mulch around your plants will help conserve moisture in the soil so you can water less, and less often.