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How to Plant Dahlias for beginners

The last frost has passed and the ground has warmed up a bit. It’s time to plant dahlia tubers! People might think growing dahlias is difficult, and while they’re not dandelions (they most likely won’t grow in a sidewalk crack), there are a few tips and tricks that can help them flourish.

I grew Dahlias— very successfully— for the first time last year and I thought I’d share my simple process. Here‘s a quick step by step and some tips.

What I use to get started

  • dahlia tubers (lol)

  • shovel

  • compost for fertilizer

  • bone meal (for phosphorous specifically)

  • trowel (small hand shovel) or hori hori (garden knife)

  • stake (I use 5-6ft bamboo)

  • measuring device (my hori hori tool has inches marked on it)

1. Choose a spot with full sun (6 hours or more per day). It’s helpful to choose an area that has direct access to water— one that can be reached by a hose. (If you’re a complete beginner gardener, check out this post for tips.)

2. Space your plants 12-18 inches apart (18-24 for dinner plate varieties. Unless otherwise stated, 12-18 inches should work great.) It can be helpful to use a measuring device to know the exact measurement. I find that in the garden, I over or under estimate quite frequently.

3. Dig holes for the Tubers. One tuber per hole. I usually dig one shovel’s deep hole. That‘s typically both wide and deep enough for a tuber. (Approximately 8-10 inches deep and 8-10 inches wide, this will allow the soil to be loosened and filled with compost.)

4. Dump a load (one to two shovels full) of compost in and around the hole. I also add a heaping tablespoon of bonemeal in the hole. Then I mix the dirt/compost/bonemeal with my hand or towel/hori hori.

5. I fill in the hole a bit, leaving between 3-5 inches of space to place the tuber. Again, I use a measuring device (my hori hori is one foot long with inches marked).

6. Place tuber horizontally in the prepped hole. I usually place visible eyes or sprouts facing up (the eyes/sprouts become the plant, not the roots). Take a look at the pictures to see a couple examples of eyes and sprouts. Sometimes the eyes are really obvious and other times they’re not. It always amazes me when I have a tuber that I think couldn’t possibly have viable eyes and then they end up sprouting through a non-visible eye anyways!

7. If you choose to stake the dahlia plant, add a stake at this time. Dont put it in after the tuber is covered because then you might accidentally hit the tuber with the stake and damage it.

When I stake, I use a 5-6 ft tall bamboo and bury it about a foot or more in the ground. Yes, a foot. It might sound excessive, but when the dahlia plant grows, you want to attach it to something secure that is anchored in the ground. As the dahlia grows, you can tie the plant loosely to the stake to prevent the plant from falling over and/or snapping.

Note—Because I grow a lot of plants (60 last year and over 200 this year), I don’t stake individual plants. Instead I use a “corral method“ and use t-posts at the end of rows and twine to corral them. If you’re growing tons of plants too, this could be worth looking into.

8. Fill in the hole and pat down. I apply light pressure. Don’t water until it sprouts. Yes, you read that right. The tuber has the sustenance the plant needs to sprout. Don’t water.

Where I live (Kitsap County) is zone 8b with an average last frost date of April 8th. This means I usually plant my dahlias around the first week of May, when the soil has warmed to about 60 degrees. If you don’t live local to me, check out this post to figure out when to plant.

Remember! It bears repeating: Don’t water the tubers until they sprout! If you do, they might rot before sprouting. The tuber has the sustenance the plant needs to sprout. (Natural rain water should be fine, although I try to plant during a clear weather day.)

I’ve learned my dahlia growing information from some local gardeners and farmers. Thanks to Carilyn, a garden coach at Kitsap Roots, Amber of Boomerang Blooms, Carolyn of Willow and Mable Garden Flower Farm, Elisa of Elisa’s Dahlias, and Krystal of Viking Flower Patch for sharing their expertise and growing incredible dahlias. They’re all worthwhile social media follows for gorgeous flower & garden pics as well as how-to videos, fun events, flower bouquets, etc.

The above instructions are the basics. Want more? Here are three extra steps you can take:

  1. Google the names of your dahlias (should be written in sharpie on the tuber itself.) You can see a picture of what the flowers should look like and learn more information about color, type, size of the bloom and plant, and time until first blooms. Pay close attention to the heights of the plants. Dahlias range in sizes from (generally) 1-6 feet! The kinds I have range from 3-6 feet. I try to put my 3 footers in front of my 6 footers so the sun can get to each of the plants.

  2. Label your stakes or stick a plant label in the ground with the name of the dahlia. This will help you remember what you planted, where.

  3. Slugs LOVE dahlias and this can be especially bad for really young plants when they just start emerging. I use a variety of homemade slug deterrents and also Sluggo. Spread it around to keep your plants healthy and growing!

That’s my current process. Hope that helps & Happy Gardening☺️

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