Summer is just around the corner, but it is already HOT in most of North America right now! This kind of heat means that your dahlias may need to be watered more often… but, HOW often?

Today, I want to talk all about dahlia watering—how we water at the farm, a few suggestions for watering in your home garden, how much water your dahlias need, and finally the very best way to know when your dahlias need a drink.

How We Water Dahlias at Triple Wren Farms

Before our dahlias sprout, at our farms we install a drip irrigation system in each row. Adding irrigation before sprouts emerge ensures that they won’t be knocked or broken by hoses or irrigation lines. Even if the irrigation isn’t needed yet because spring rains are giving adequate water, we still get it ready for the day we DO need it. We choose to water with drip irrigation for a few key reasons. We are growing many acres of dahlias, and  it’s important to us to conserve as much water as we can. Drip irrigation also helps us to target water right to the dahlia roots and helps us to avoid losing a lot of water to evaporation.

Watering Your Home Garden

There are lots of different ways to water, but they all boil down to either a soil-level irrigation system or overhead watering, i.e. a sprinkler.

Soil-level Irrigation

Soil-level irrigation is a good option for the reasons we mentioned above—conserving water, targeting the water right to the tubers, and avoiding water loss to evaporation. In a home garden, a soaker hose is a really easy option to wrap through your beds or drape over pots. You could even use a timer and set it to water for a specific number of minutes daily (Here is our favorite battery-powered timer.)

Overhead Watering

Overhead watering is also a good option for your home garden. Using a sprinkler could even be a better option than irrigation if you’re in a hot climate and using misting/sprinklers to keep your dahlias from overheating mid-summer. It can also be helpful for washing off pests if you tend to struggle with aphids or spider mites. Dahlias are amazing and can take in water through their leaves, so overhead watering allows dahlias to absorb water both from the soil and from their leaves. We recommend overhead watering during the morning to avoid water loss due to evaporation. A caution against overhead watering is that it could spread powdery mildew spores, so you’ll need to weigh if that is a concern for your growing conditions or not.

Deciding how to water your dahlias really depends on your goals and the way you’ve set up your garden. As long as your dahlias are getting the right amount of water, there really isn’t a right or wrong way to water them.

Speaking of the right amount of water…

How Much Water Do Your Dahlias Need?

A good rule of thumb is that your dahlias need about 1 inch of water per week. However, that will vary, since humidity, soil content, and precipitation all affect your watering needs.

Soil Content Affects Watering

The composition of your soil really affects the amount of water your dahlias will need. For example, we have two different soil types that we’re managing, because the land we’re farming in Abbotsford has very different soil than our Ferndale farm. Our two farms are only 11 miles (18.5 km) apart as the crow flies, but the soil composition and microclimates are quite different! In Ferndale, we have very quick-draining sandy loam. Water never sits in the soil there, so it requires more frequent watering. Every winter we work hard to incorporate more organic material into our fields so that we improve its water retention and fertility.

As we develop the land where our Canada dahlias are growing, we are learning that it has a much higher clay content. We water it less that we water our U.S. farm so that our tubers and plants don’t sit in too much water throughout the season, because the higher clay content means that it doesn’t drain as quickly. 

This is a perfect illustration of why it’s almost impossible for you to measure how you should water your dahlias based on someone else’s plan. Your unique microclimate has its own unique needs.

How to Know When Your Dahlias Need Water

So, how do you know when your dahlias need water? You have to get your fingers in the soil! Every time you’re in the garden, push your fingers into the soil of your beds or pots. Is the soil dry? You need to water more. If the soil is soggy, you likely need to water less. Water needs change in the garden as the seasons change, so monitor frequently in order to learn more about the rhythms of your microclimate and to keep your fingers on the pulse of your garden. 

This kind of tactile approach to gardening is more effective than gadgets that monitor for you, because it gives you a personal experience with your dahlias, and also because it forces you to get into the garden and spend time each week enjoying and observing the changes that happen as it grows.

By carefully monitoring your soil for dryness, you can adjust your watering schedule throughout the season accordingly. Remember that pots usually require more water than raised beds or garden plots since their sides are often heated and dried out by summer sunshine.

Three Keys to Excellent Dahlia Health

To keep your dahlias thriving, focus on three essentials: protect them from weeds and pests, ensure they receive adequate watering, and fertilize them regularly. Check out our blog posts about pest management and fertilization for more info about the other two sides of this “dahlia health triangle.”