Growing flowers in flower or window boxes allows you to plant a variety of flowers in a small space. These mini-gardens require little care other than watering and fertilizing to keep them looking fresh and bursting with color. Because water leaches nutrients from the soil quickly in containers, your plants need more fertilizer. You can easily solve this by apply liquid fertilizer as part of your routine watering once every 10 to 14 days--and watering with plain water at other times.
Water flower boxes whenever the soil feels dry 1 inch below the surface of the soil. Many require daily watering; boxes and containers drain quickly and dry out easily in warm weather. Boxes containing large flowers or placed in the direct sun may require water twice a day.
Water plants in the morning when temperatures are cool. This provides the moisture they need as temperatures rise, reduces stress to plants and allows foliage to dry in the summer sun. Avoid watering plants during the heat of the day. Water again, if needed, in early afternoon when temperatures cool. Avoid watering late in the evening; wet foliage during cool, damp nights promotes disease.
Set your hose attachment to a fine spray to give plants a gentle shower of water. Water until water runs free of the bottom of the flower box and soil is saturated. Use a flower wand for difficult-to-reach boxes.
Watch for signs of wilting and check the soil often to determine if your plants require more frequent watering. The specific flowers you are growing, the rate of plant growth and weather conditions all effect how much water your flower box needs.