Dear Dahlia Doctor – My Dahlias are Wilting in the Heat

Dear Dahlia Doctor,

This is my first year planting dahlias and I have a lot to learn. My plants (below) are huge but nothing has bloomed yet. The tubs I’m using seem too small, which I’ll need to fix next season.

Dahlias suffering because of the hot summer

Seattle isn’t supposed to get this sunny!

Right now I’m worried because lots of leaves are drying in the heat and I’ve been trimming them off. I’ve been watering every other day because it’s too hot. Are they okay? Will they still bloom? When is it normal for them to bloom? What should I do to treat them best?

Thanks,
Wilting in the Uncommonly Hot Seattle Summer

Dear Hot Seattle Summer,

It would probably be a good thing for you to water your plants daily if temperatures are higher than average or if your leaves are getting sunburned.

There are some easy things you can do for your dahlias during August and September to help your blooms be the best they can be.

  • Keeping your plants well watered during hot weather is important; if the leaves are still drooping as the evening cools, be sure to supply enough water so they regain their turgid form.
  • Make sure to water early in the morning or in the late evening when the temperature is cooler.
  • Break off the lowest leaves to allow air to circulate under and around the bushes.
  • During hot weather, fertilize during the coolest part of the day (early morning or late evening).
  • Keep the plants gently tied up to their stakes.

Another possible reason for sunburn on plants is the sun reflecting off of hot walls near the plants. Your plants may need a little shade in the hottest part of the afternoon. Do you have a beach or patio umbrella that you can put up to help those pasty, plaid-wearing Seattleite dahlias survive the summer sun?
If the tubs are easily moveable, you might try relocating them to a shadier area of your patio.

The good news is that stressed plants will still bloom it’s just the number and quality of the blooms that will be affected. Maintaining a garden is usually a learning process – green thumbs don’t grow on everyone and transplants are expensive even with insurance, so don’t worry if something doesn’t grow the “right” way the first time around.

Hope that helps you, I’d hate to imagine the bill for all the bottles of SPF 100+ sunblock you’d otherwise have to purchase to cover all those leaves!!

- The Dahlia Doctor

Dear Dahlia Doctor, My Leaves Look Funny

Dear Dahlia Doctor,

My leaves are a really funny color… they also have holes in them. Do you have any ideas about what my problem could be? How do I fix it?

 

Thanks,

Unbe-leaf-able Colors

Dear Unbe-leaf-able,
The holes in the petals are caused by earwigs.  Thats why they come to visit.  To eat. You can use Sluggo to combat the earwigs, refer to the previous post about earwigs to learn more.

As for the leaves, it appears that you might have Red Spider Mites. They make their home on the underside of the leaf, where they puncture the plant’s cells in order to feed. If they build a colony, you will see a very fine webbing on your plants where they lay teeny-tiny eggs. It is possible for a single, mature female spider mite to lay over one million eggs in less than a month. If you can’t get your hands on a commercial-grade spray, a more natural way to go is to use Monterey Natural Mite & Insect Control, which is “effective against all stages of mites and pest insects” and “provides rapid knockdown and residual control of spider mites, whiteflies, aphids, scale, mealybugs, leafhoppers, caterpillars and many more.” There is also Mite-X Spider Mite Killer. One thing to note is that the miticides may not affect the eggs, so your would need to repeat the application of the spray every 10-14 days. Another product to try would be Vegol Year-Round Pesticidal Oil. You could also try Bang! which helps heal leaves that were damaged by spider mites.
         

Though we are nearing the end of the season, you could still give these a try.

- The Dahlia Doctor