Watering may be one of the trickiest aspects of growing annual flowers. Like many plants, annuals need consistent moisture in the soil in order 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: Climate encompasses a wide range of factors, such as the amount of average rainfall, the high and low temperatures, the relative humidity, and the amount of wind. (Click here for climate in detail) 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. (Click here for container gardening)
• 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: Different soil types affect how often a garden needs water. (Click here to determine what type of soil you have) Luckily, when you grow annuals, you can amend the soil with organic matter on a yearly, if not seasonal, basis. 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, leaving little for the flowers. Maples in particular have roots so close to the surface that it’s almost impossible to apply enough water to satisfy the tree and the flowers. The farther from the trunk of the tree you place your flowers, the more room they have to spread their roots, and the less they have to compete with the tree for water and nutrients.
  If you plan to plant in a shady area, choose annuals that don’t need direct sunlight to thrive. Impatiens, forget-me-nots, and browallia are good choices for the dark corners of your yard.  ....read more