Planting dahlias can feel intimidating – that's why we've created our series of grow guides to help you every step of the way. Click on the videos below to learn about the full process and be sure to keep reading for more unboxing and planting information.
Stage 1: Planting Your Dahlias
When you receive your dahlias, you need to get them out of the box used for shipping ASAP Once them out of the box used for shipping ASAP. Once removed from the box for shipping you can keep your dahlias in the packaging we provided to you. This is a perfectly adequate way to store your dahlias until it's time to plant.
Be sure not to let them freeze or get way too hot before you bring them out to plant. We keep ours at 50F until we plant them in the ground. A cool basement that stays at a stable temperature is ideal.
Again, don't let them freeze or they will rot out and turn to mush.
How to know when it's the time to plant?
The trick with planting your dahlias boils down to a couple factors to ensure success. First thing is to make sure the soil has warmed up enough before you plant them. If you don’t they will have a greater chance of rotting before they sprout. Once the soil conditions are right and you plant, do not over water the tubers – water just enough so the soil is moist but not soggy wet. Once we plant outside we usually don't water until the sprouts have come out of the ground 3-4 inches.
*Pro Tip* If you want to get a jump start on your dahlias you can plant them in a 4 inch pot with a good organic potting mix. This will help your dahlias to sprout and get off and running. A warm window location that receives a good amount of sunlight throughout the day will be perfectly sufficient for pre-sprouting in a pot.
Once the soils have warmed up enough (late May to June for us in southern Maine) you can transplant them outside – be extremely delicate to not break the sprout once planting.
Location and soil prep
Planting location is yet another factor that will greatly affect the success of your dahlias. Dahlias like a spot that receives at least 8 hrs of sunlight per day. Once your tubers start growing they will love a good amount of sunlight to grow strong and healthy to produce the blooms that we are all hoping for.
Choose a well drained location and keep in mind that dahlias need at least 16 inches of spacing from other plants on all sides. We plant intensively and 16 inches works well for us because space is a premium. If we had a smaller amount of dahlias to plant I would recommend 24 inches on all sides to make sure they have enough space to bush out.
Preparing the soil
Dahlias are hungry plants (they need to eat to make dem blooms). Therefore a healthy dose of good diverse compost, and a handful or two of some organic granular fertilizer will be a welcomed addition at planting time.
*Pro Tip* Bone Meal is another highly recommended amendment at planting time. Organic Bone Meal can be purchased at most garden centers.
Check our video tutorial here that provides a visual on the planting process.
Dahlias are known to be a bit high maintenance. They kind of have a bit of a Goldy Locks thing going on when it comes to being watered. When dahlias are just planted they don’t need to be watered to avoid tuber rot. But when dahlias reach the 12 - 16 inch range you can let it rain. Assuming your plants are receiving a healthy dose of sunlight, feel free to keep the soil moist with regular watering. Once dahlias reach 16 inches they really start to grow quickly and with all that photosynthesis going on they will need water.
Adding a bit of liquid fish and seaweed fertilizer once a week, when you water, will also be a welcomed addition to your plants health. This is something that can be found at most garden centers and make sure to follow the application instructions on the bottle, as a lot is not always better.
Topping is one of the most important steps in Dahlia growing. It's vital if you want to drastically increase the amount of blooms per plant. Topping aka pinching, is done to remove the center stem and promote side shoots or branching. By removing the center shoot you will cause the plant to bush out and grow many main shoots. More main shoots equals lots of luscious booms down the road.
So how do I do this? Timing is everything when it comes to topping. Topping is performed when the plant has grown 4-5 sets of side shoots (roughly 12 inches tall but depends on variety). Once your dahlia tubers sprout they will produce a stem and once that stem gets to roughly 12 inches you will begin to see that it has side shoots. Side shoots almost always grow opposite of each other in what we call sets. Once your plant has 4 -5 sets of side shoots (8-10 branches total) and are sturdy enough, it's time to top your plants. To top you can use sheers or your thumb nail against your pointer finger to cut out the center shoot ABOVE the 4-5th side shoot set. That's it, you're done.
*Pro Tip* It’s important to note that all dahlia plants and varieties will not be ready for topping at the same time. On our farm it's usually a 2 week window at the end of June where we perform almost all of our topping. If you got a late start with your dahlias you might want to be careful topping the plant as it can throw off the momentum of the plant and you won't get any blooms at all. Like i mentioned you should be wrapping up topping by the early part of July (for us in Southern Maine)
Now that your plant does not have its center shoot it will begin to branch out from the remaining 4-5 sets of branches below the top you made. This might seem drastic to do this move but trust us and the oodles of other dahlia growers that strongly recommend topping to increase blooms.
Harvesting Dahlia Blooms
Joy Joy Joy! Your dahlias are blooming! Don’t be shy if you want to cut your dahlias and enjoy them in a vase, dahlias love to be cut and will only respond back with more blooms. If you let your dahlias fully bloom on the stem make sure to deadhead the past blooms to stimulate the plant to continue blooming. Once dahlias, and most flowers, reach the seed forming stage after blooming they will become less productive because they have reached their reproductive goals.
Dahlias should be harvested with sharp shears once about 75% of the dahlia petals have unfurled from the center of the dahlia. The center of the bloom should look tight but again, most of the petals have opened up. Unlike other flowers dahlias don't open up much at all after being picked.
Freshly harvested dahlia blooms should be placed directly into water to be enjoyed in any kind of flower arrangement. Truthfully a bouquet of dahlias just by themselves is wonderful. If you keep the water fresh in your vase and the flowers out of direct sunlight you can expect 5-7 days out of most of your dahlia cuts. This will definitely depend on the varieties. (From our perspective the ball shaped dahlias seem to last the longest) Another tip is when you change the water in your vase, give your flowers a fresh cut inch above the bottoms of the stems.
Digging and Dividing
For more information about digging and dividing please see our videos on these topics here.