Dahlia Growing Tips for Early Summer

We’re in an in-between season at the farm. The busy spring season is over, and all the planting and shipping is done, but we’re still waiting on the bounty of blooms. As we watch and wait for our dahlias to bloom, there is still plenty to do.

Watching for Pests and Pest Prevention

Every week, we spend hours just observing our plants. We’re looking for pests or pest damage and we’re monitoring the health of our plants. One of the main ways we prevent pests is by weeding. Removing weeds destroys the hiding spots of harmful insects.

Now is the best time to weed because most weeds are super small, and their roots haven’t had a chance to nestle in with our tubers’ roots. Weeding carefully now also allows us to keep tabs on every single dahlia on our farm every single week.

Beyond harmful insects, some other common pests you may come across are slugs and rabbits. In the Pacific Northwest, slugs are the pest we have the most trouble with. Slugs can decimate emerging dahlias. We prevent this by applying Sluggo Plus before the slugs have a chance to munch on our dahlia babies. We apply after planting, and re-apply after rainy periods. You can apply Sluggo sparsely (we do!), but I wouldn’t skip it. It is definitely an essential in our gardens while dahlias are small.

To deter rabbits, we suggest cage traps which will allow you to capture the bunnies. Talk with your local wildlife control office about the best places to release rabbits you capture. Or… (and I know this sounds weird) most hunting stores sell bottles of coyote or cougar urine which hunters use to disguise their scent. Dripping a few drops on an old t-shirt and staking the t-shirt squares in your garden with shish-ka-bob skewers is a very effective way to deter rabbits from entering. If rabbits smell signs of a large predator, they will avoid that area. 

If you’re experiencing trouble with pests and need help figuring out how to get rid of them, we’d recommend reaching out to your local extension agent or joining your local dahlia society and speaking with your “dahlia neighbors” there. 

When to Start Watering

In most cases, dahlias do not need water until the foliage is 2-3 inches tall. If you water before that, you run the risk of rotting tubers. However, if you have potted dahlias, those need to be watered as soon as the foliage emerges. After the foliage emerges, we water our dahlias with drip irrigation about 1 inch per week. We monitor continually to keep the balance between not letting our soil dry out and not letting the tubers soak in too much water.

Mulch Your Dahlias

If you haven’t already, consider adding some mulch to your dahlias. Mulching around your dahlias keeps your dahlias’ “feet” cool, and can prevent both irrigation evaporation and sudden rain shower puddling at the base of your plants.  

Did you know that mulching doesn’t mean just using wood chips? When we started flower farming in 2012, we thought that mulch was another term for the wood chips that many people put in their landscaping beds. But actually, mulch is a term for any ground cover that covers your bare soil, including biodegradable plastic mulch, wood shavings/chips, ground cloth, lawn clippings, leaves, etc.

Fertilize Your Dahlias

About 6-7 weeks after planting, gently work a low nitrogen fertilizer into the top 1″ of soil around your dahlias, and water in to activate the fertilizer. (Using a time release fertilizer at this point is just fine, and likely will eliminate any need for a third mid-season fertilizer application.) We recommend a low nitrogen fertilizer so you don’t end up with lots of luscious foliage, but very few blooms. (Click through to find more information about how to fertilize dahlias and what in the world N-P-K means.)

Get Ready to Stake Your Dahlias

Your dahlias may be small now, but dahlias grow SO fast as the days warm up, and they’ll need a shoulder to lean on before you know it. If you didn’t add a stake when you first planted your tubers, you’ll need to get a plan in place now so you’re ready when your dahlias need it. We’re written all about how we support our dahlias over on our blog.