When to Water Annuals in Your Garden

By The National Gardening Association, Bob Beckstrom, Karan Davis Cutler, Kathleen Fisher, Phillip Giroux, Judy Glattstein, Mike MacCaskey, Bill Marken, Charlie Nardozzi, Sally Roth, Marcia Tatroe, Lance Walheim, and Ann Whitman from Gardening All-in-One For Dummies

Watering may be one of the trickiest aspects of growing annual flowers. Like many plants, flowering annuals need consistent moisture in the soil to grow and bloom beautifully. Annuals aren’t very forgiving if they don’t get the water they want, when they want it.

If you let some of these finicky plants dry out, they’ll stop growing and quit blooming for good. (Drowning your plants has that same effect.) If they don’t die, most under- or overwatered annuals at least shut down for a while. For a more permanent plant, a temporary halt in growth may not be the end of the world. But with annuals, fast, consistent growth is critical. If the plant stalls, you may lose a good part, if not all, of the blooming season.

The amount of water that annuals need to stay healthy and full of blooms depends on a number of factors:

Climate: If you live in an area where rainfall is regular and reliable watering isn’t a constant chore, except during prolonged dry spells or periods of drought. In drier areas, you must water almost every day. You have to water container-grown annuals even more frequently than your plants in the ground. In fact, daily watering of annuals in containers is essential in almost all climates during certain times of the year.
Weather: Climate is determined by the average weather where you live on a season-to-season, year-to-year basis. Weather is what’s happening outside at any given moment. Out-of-the-ordinary weather can wreak havoc on your plants. Adjust your watering as follows:
- Water less: Cooler temperatures, cloudy or overcast conditions, low wind, high humidity, and rain
- Water more: Warmer temperatures, bright sunshine, high wind, low humidity, and no rain
Soil type: Soil type affects how often a garden needs water. Luckily, when you grow annuals, you can amend the soil with organic matter. Adding organic matter, such as compost, leaf mold, or ground bark, helps sandy soils to retain moisture and helps break up clay soils to improve aeration and drainage.
Garden location: In general, shady gardens need less water than those planted in direct sunlight. By blocking the sun’s heat, shade cuts down on the amount of water that evaporates from the soil. However, in places where trees are responsible for casting the shadow, the tree roots may be greedily hogging all the water.
Type of annuals you’re using: Some annuals can get by on less water than others. Amendi your soil and group plants according to their water needs. If you garden in containers you have much more control because you can move the pots around if your plants begin to complain about their present location.

The water needs of your annuals vary with the weather and the seasons, and you must make adjustments accordingly. Here are two easy ways to tell when your plants need water:

When an annual starts to dry out, the leaves get droopy and wilt. The plant may also lose its bright green color and start to look a little drab. Your goal is to water before a plant reaches that point, but the plant will tell you when it needs water more often.
Most annuals need water when the top two to three inches of soil are dry, so take a small trowel or shovel and dig around a bit. If the top of the soil is dry, you need to water.