It's important to know the most critical time in a vegetable's growth to water. Mulching helps reduce the need for extra water.
It's always better to water infrequently and deeply than frequently and shallowly. Frequent light waterings only moisten the top few inches of the soil. The roots will stay where the water is and when dry conditions occur, the plant is more likely to suffer water stress due to the shallow roots. Deep waterings send water down 6 inches to a foot into the soil and the roots will follow. These plants will be more likely to survive a bout of drought.
If the plants aren't indicating it's time to water, the soil will. You can also stick your finger in the soil. If you dig down 3 to 4 inches into the soil and it's still dry, it's time to water.
So, while it's important to keep plants properly watered all season long, there are critical times of the growing season to water. Here's a chart adapted from the book, Vegetable Gardening for Dummies (2009, Wiley), showing the most critical times to water your produce.
| Vegetable | Critical Watering Period |
|---|---|
| Bush bean | When flowering and forming pods |
| Broccoli | When forming a head |
| Brussels Sprouts | When forming sprouts |
| Cabbage | When forming a head |
| Carrot | When forming roots |
| Cauliflower | When forming a head |
| Sweet corn | When silking, tasseling, forming ears |
| Cucumber | When flowering and developing fruit |
| Eggplant | From flowering to harvest |
| Lettuce | When true leaves form |
| Melon | During fruit set and early development |
| Onion | During bulb enlargement |
| Pea | When flowering and during seed enlargement |
| Pepper | From flowering until harvest |
| Potato | When tubers set and enlarge |
| Pumpkin | When fruits form |
| Radish | When forming roots |
| Spinach | When true leaves form |
| Summer squash | When forming buds and flowering |
| Swiss chard | When true leaves form |
| Tomato | From flowering until harvest |
| Turnip | When forming roots |
Not only is the timing of your watering important, how you water makes a difference too. Depending on your area and the season, there may be watering restrictions in place or water may be very expensive. Using efficient watering systems not only will be better for the plant, it can save water and money for you.
Here are some of the common ways to water your garden, with advantages and disadvantages of each. The automated systems described below are best used with a timer that will turn your watering device on and off so you don't have to remember.
Hand water — This is probably the most common way gardeners water. While it is one of the easiest watering methods, it's sometimes not the most effective or efficient. It's common to waste water sprinkling pathways. Also, the water may be distributed unevenly. Hand watering with a hose or watering can is best used on containers and individual plants. In fact, the most efficient way to hand water is to create a basin or furrow near the individual plant or row and fill it with water. Let it sink in, then move to the next basin. This works particularly well early in the season, when plants are small.
Sprinklers — This is probably even easier than hand watering because all you do is set up the overhead sprinkler and let it run for a designated period of time. While the water soaks into the ground well, the down side is you'll be wasting lots of water in the process watering pathways. Also, this type of watering should be done in the morning so the leaves dry before evening. Wet leaves at night are an open invitation to disease.
Soaker Hoses — A more efficient way to water is to lay soaker hoses around plants and along rows. These low-flow hoses weep water into the soil around plant roots and are less likely to waste water. They work best laid under plastic mulch used around warm season crops, such as tomatoes and melons. Soaker hoses also work best on flat ground to evenly distribute the water.
Soaker hoses concentrate water near roots where the plant needs it the most.
Drip irrigation — Drip irrigation is similar to soaker hoses in that you'll be focusing the placement of water near the plant roots. However, it's even more efficient and wastes even less water. The downside is the cost and maintenance. There are more parts to the drip irrigation system that needs to be checked frequently to open clogs and fix leaks. Plus, drip irrigation is more expensive than any other watering system.
Mulch — Though not a watering system per se, mulch is critical to conserving soil moisture and keeping weeds away. Organic mulches such as straw, pine straw, bark mulch and untreated grass clippings will reduce the amount of watering and weeding you'll have to do during the growing season. Weeds are important to control because they will compete with your plants for water. Plastic mulches conserve moisture too, but work best with a soaker hose or drip irrigation lines running under them to keep the plant roots moist.
