Ask the Experts: Watering outside plants
AMES — Knowing when to water and how to water plants is one of the most important aspects of gardening and can make all the difference to the health of plants. Iowa State University Extension and Outreach specialists answer questions about watering plants in containers, gardens and lawns. To have additional questions answered, contact the experts at hortline@iastate.edu or call 515-294-3108.
How often should I water plants in containers?
The frequency of watering varies considerably from container to container. Watering frequency depends on size and type of container, potting mix composition, plant species and weather conditions.
Plants growing in containers should be checked daily (especially in summer) to determine if they need to be watered. If uncertain about the need to water, poke your finger into the potting soil. Water the container when the potting soil at the 1-2 inch depth is dry. Watering frequency may vary from once or twice a day (small container, hot windy weather) to once or twice a week (large container, cool weather).
When watering plants in containers, continue to apply water until water begins to flow out the drainage holes in the bottom of the container.
Do not allow the potting soil to dry out. Potting soils shrink and pull away from the sides of the containers when completely dry. Dry potting soils are difficult to moisten as water tends to flow between the potting soil and container and then out the bottom of the container (while the potting soil remains dry). Containers that have been allowed to dry out completely should be placed in a tub of water for 20-30 minutes to remoisten the potting soil.
How often should I water flower and vegetable gardens?
Most flowers, vegetables and fruits perform best when they receive 1-1.5 inches of water per week. A deep watering once a week should be adequate for fruit, vegetable and flower gardens in dry weather.
How often should I water my roses?
Modern roses, such as hybrid teas, floribundas and grandifloras, require watering during hot, dry weather. The frequency depends upon weather conditions and soil type. In most gardens, a thorough watering every 7-10 days during dry weather is sufficient. If possible, apply water directly to the soil around each plant. Overhead watering wets the foliage and increases disease. If overhead watering is unavoidable, morning is the best time to water roses.
How often should I water my lawn?
Most lawns in Iowa require 1-1.5 inches of water per week. Apply this amount in a single application or possibly two applications 3-4 days apart. Avoid frequent, light applications of water which promote shallow rooting and lush growth.