The key to watering newly planted flowers is giving them about 1-1.5 inches (2.5-3.8 cm) of water each week. Apply this water deeply every two to three days rather than sprinkling a little bit every day. Deep soaking builds strong roots that can handle dry spells later on.
I learned this lesson after killing a whole bed of zinnias my first summer gardening. I watered them every single day with just a quick spray from the hose. The plants looked great for two weeks then wilted and died when I went on vacation. Their roots had stayed near the surface chasing my light watering.
The next year I switched to deep watering twice a week. I would let the hose run slow at the base of each plant for a full minute. Those zinnias grew roots eight inches deep and survived a two-week dry spell without any extra care from me.
Your new flower watering schedule depends on your soil type and weather conditions. Sandy soil drains fast and needs water more often. Clay holds moisture longer between waterings. Hot windy days dry out your plants faster than cool calm ones. Adjust your timing based on what your garden tells you.
Missouri Extension says you need about 1.5 inches of water per week for your annual flowers. That drops to one inch during cool cloudy weather. You may need two inches or more when temps climb above 90°F (32°C).
Figuring out how much water for new plants starts with checking the soil itself. Push your finger two inches into the soil near your flowers. If it feels dry at that depth you need to water. If it still feels moist then wait another day and check again.
Morning watering works best for your new flower health. Your leaves have time to dry before evening which cuts down on fungal diseases. Roots absorb water better during the cool morning hours before heat makes your plants close their pores to save moisture.
Mulch helps you water less often once your flowers get established. A two to three inch layer of shredded bark or straw keeps soil cool and moist. I cut my watering in half after mulching my flower beds for the first time and my plants looked better than ever.
Stick with your new flower watering schedule for the first month after planting. Your flowers need consistent moisture to spread their roots and settle into their new home. After that first month you can back off to how much water for new plants keeps the soil moist at root level without overdoing it.
Read the full article: When to Plant Flowers: Month-by-Month Guide
