How Often Should You Water Dahlias?

Megan Haworth
Mar 31
2 min read

If you’re just joining us, you can catch up on Week 1 (what a tuber is), Week 2 (how to plant), Week 3 (staking), and Week 4 (soil and fertilizer).

If you’ve been thinking about growing dahlias, you might be wondering:

“How much should I water them?”

It’s a great question, and one that makes a bigger difference than you might expect.

I once heard a dahlia expert say that almost all problems with dahlias can be traced back to not enough water.

That surprised me at the time, but I have to say, I’ve found it to be true.

Dialing in my watering has been one of the biggest improvements I’ve made in the health and vigor of my plants.

How Much Water Do Dahlias Need?

As a general rule, dahlias want about an inch of water per week.

Once the plants are tall and the weather turns hot, they’ll need more.

What About Rain?

In my area here in Pennsylvania, we average just under an inch of rain per week during the growing season.

That means nature often does a good portion of the work for us.

In May, when we typically plant, I usually don’t need to water at all. There’s plenty of natural moisture in the soil from spring rains. In fact, too much water early on can cause tubers to rot.

When to Start Watering

By June, I start to pay attention. Some weeks we get enough rain, and some weeks we don’t.

By July and August, I have to plan to water regularly. At that point, the plants are large and working hard to produce flowers, and hot weather can put them under a lot of stress.

Watering in Pots vs. In the Ground

If you’re growing dahlias in pots, you’ll likely need to water daily. Containers dry out quickly, especially in warm weather.

If you’re growing in the ground, a deep watering once or twice a week is usually enough.

Simple Ways to Water Dahlias

For a few plants, a watering can or hose works just fine. It also gives you a chance to check in on your plants regularly.

If you’re growing more, it’s worth thinking about something a little more hands-off, like a sprinkler or a drip hose.

Last year I installed drip tape in my dahlia beds, and it made everything much easier.

This is one of those areas where a little planning ahead goes a long way.

Keep It Simple

Watering doesn’t have to be complicated. Pay attention to your plants, notice the weather, and adjust as needed. A consistent watering routine will do more for your dahlias than almost anything else.