When dahlias are established, water 2 or 3 times a week and more in hot, dry climates. Be prepared to tend to plants before or after rain, when open blooms (especially large ones)... Learn how to grow dahlias in your garden with the RHS expert guide on choosing, planting, feeding, pruning and propagating plants. Water Frequently After Planting. A woman wearing white gloves plants a small dahlia seedling with heart-shaped, serrated green foliage into grey-black soil in a sunny garden. ADS Dahlia University - Watering. Dahlias produce large plants and therefore need a fair amount of water. How to WaterDahlias. Step 1 - Check the soil around the base of your Dahliaplants. You want to wait until the soil around your plant is almost completely dry so as to not overwater. Dahliaplant irrigation routines should focus on long and deep watering sessions. This process will promote stronger, studier plants and better root growth. Soon after planting, Dahlias don’t need watering very often to become established. I find that a deep watering right after planting should sustain them until they emerge from the soil. Plantdahlia tubers and plants as you would when planting in the ground, just under the surface of the compost. Then add a stake, a label and water well. Once dahlias are up they love water! After they are established and getting taller they are going to need a lot of it. When the plants are about 3” tall, you can start watering gradually. The best way to monitor your dahlias’ water needs and health is to be out in your garden every day observing your plants. If your plants are droopy... The size and age of the plants will be important too, as June Nash from The National Dahlia Society explains: “Water sparingly at first but gradually increase this as the plant grows. DahliaPlanting Instructions 3. We're planting three clumps of tubers per hole.Our large dahlia garden is planted and fertilized. Now all we need is regular watering and a few weeks. When making a plan for watering your dahlias, I recommend planting them in a location that they can receive a good amount of water and sun all summer long. If starting tubers in containers indoors, water your tuber once after planting and leave in a warm, sunny location. Your soil should be moist, not wet (refer to section “WateringDahlias”).
