Time to start planting your tubers
Oh, I am so excited for this dahlia season to start. It is as if my best friends have been away for the winter but now it is time for them to return. People ask if it is difficult to grow dahlias and the honest answer is yes it is a little bit tricky. The most difficult part is to get the tubers to sprout and grow. So I am going to go through all the steps I go through so you can be so successful as possible.
But before I share what I do with you, I just want to have a quick conversation about tuber size. Not all dahlias are created equal. I feel that there is a misconception about how a healthy tuber should look. It almost reminds me of the expectation people have about a macaroon. In the world's mind a macaroon should be a perfect shade of pastel and consists of perfectly shaped half spheres glued together with the perfect amount of filling. This is the image, but not the truth. In a French pâtisserie macaroons do not look like that, they are far from perfect and they still taste amazing.
The same goes for dahlia tubers, they are very rarely perfect. As long as they have all the right parts they will grow. Not even size matters, some varieties produce giant tubers and others mini tubers. But after the tubers sprout, they will all grow into healthy plants. Trust me. It's almost like us, not everybody can be swimsuit models.
Two tubers of the same variety. On the left the tuber I am keeping to grow beautiful tubers to share with you next season versus the one on the right which I am sending to you.
Where should I plant my dahlias?
I think the best place to grow your dahlias is in a separate bed with its own irrigation system. It is possible to grow dahlias as part of your garden landscape, but then you should give them a very sunny spot with afternoon shade. They need at least 7 hours of full sun to be successful. You also need to control the amount of water they receive during the sprouting phase. If the tubers are too hot or too cold, too dry or too wet, they might rot before they start to grow. For the health of your dahlia plants it is also better not to water them with overhead sprinklers. I prefer to flood them or use drip irrigation. The other thing to remember is that most of your dahlias will need support, netting or bamboo canes to keep them from breaking or falling over when they grow tall and start to flower. So after all this being said I come back to the point I made in the beginning, grow your dahlias in their own bed, because then you can control the water, sun and support for your plants during the whole growing season. Can I grow dahlias in pots? Yes you can grow dahlias in pots or raised beds, but you should choose shorter varieties if you plan on growing them in pots. The other important thing to remember when growing in pots is that pots get very warm and that you will have to water your pots almost every day during the hot summer months.
How should I prepare my dahlia beds?
Dahlias will grow in almost any soil type from sand to clay. The only difference is that you will have to control watering depending on the water retention of the type of soil you have in your garden. If it is sandy you should water more often and if it is clay you should water less. I start every season by cleaning my beds from weeds that might have grown during the winter. I level my beds to make flooding them easier once we start to water the plants. For the rest I do not disturb my soil, because it is not good for the microorganisms in your soil when you till the earth.
Start to plant your tubers
I water my bed a week before I want to start planting because I want the soil to be moist when I plant. Then I make a 20 x 20 x 20 cm hole for each tuber. The soil from the hole I keep on the side to fill the hole back up with after the tuber has been planted. The holes are about 40 to 50 cm apart and in 1 bed I plant 2 rows.
In the picture you can see my bed with holes made ready for planting.
So before I place the tuber in the hole, I put about a tablespoon full of fertilizer into the hole and fill it halfway with soil. Then I mix the soil and fertilizer. I will then fill up the hole until it is the right depth so that after I lay the tuber down it will have about 5cm of soil on top of it. This depends on the size of the tuber. I place the tuber horizontally in the hole and then I fill the hole up with the remaining soil. Then I use an insecticide registered for killing worms and spray it on the area where the crown part of the tuber is. This will protect your new shoot from being eaten or cut by cutworms which I have a problem with. If slugs are a problem in your garden, you should scatter some slug pellets to keep your new emerging shoots safe.
Step.1 Pour a little bit (15ml) of fertilizer into the hole you dug. I use foliage fertilizer when I plant.
Step.2 Fill the hole halfway with soil and mix the soil with the fertilizer.
Step.3 Fill up the hole with more soil to the correct planting depth. The tuber must be under 5cm of soil after you cover it.
Step.4 Place the dahlia tuber horizontally in the hole.
Step.5 Cover the tuber with the remaining soil.
Step.6 Spray the area where the new sprout will grow with a pesticide. I struggle with cutworms and spray every tuber with PROTEK Knox Worm.
Watch my planting video on Instagram
Then I insert a plastic stick to which I attach the name of the dahlia variety. After the bed has been planted I will put down a thick layer of mulch to keep the soil cool and also to help the beds from drying out too quickly. The mulch I use is alfalfa hay, but you can also mulch with compost, pine needles or any organic material you have available.
Now the hard part starts
So the hardest part of growing dahlias is to get the tuber to sprout and grow roots. If the soil is too hot or cold, too wet or too dry, your tuber can and will rot before it even has a chance. The best way to explain it is to think about a dahlia tuber as a potato. You know that potato pocket you left in your pantry for a few weeks and when you open it up you find potatoes that have big fat white sprouts. Well the same will happen to your dahlia tuber. If you leave it in your pantry in a potato pocket it will sprout. So now you realize that the tuber needs absolutely nothing to start to grow. If the temperature is ideal your tuber will sprout without water or soil. Everything your tuber needs is stored as starch inside the tuber. The next important thing to remember is after the tuber sprout, it will start to grow roots, the sprout will grow its own roots and immediately start growing a new little tuber to start storing food for next season, the tuber you planted often rots away and become food for your earthworms.
I hope this helps you to understand how important temperature is for your tuber to sprout. This brings me back to my August Newsletter where I told you to keep your tuber in the bag and growing medium I send it in. Just check that the growing medium is slightly moist and open the bag half way for some ventilation. CLICK HERE IF YOU MISSED IT If your tuber has a sprout and a few roots it will be much easier to grow, then you can start watering immediately after planting and you know your sprout will push through the soil very soon.
The tuber from my previous post after being in my kitchen for 3 weeks.
I think this is the easiest way especially for beginners. I grow dahlias on a large scale, so this is not an option for me. What I do is to carefully check on my tubers daily. Each tuber gets watered individually and I even shade the bed with frost cloth if the days get too warm, anything to get the perfect temperature to get the sprouts through the soil. I also plant spare tubers in pots to replace the tubers I lose along the way. And let me tell you, I also lose dahlias to rot although I have been growing them for a few years. This is the tricky part, but if you master this they will bring you so much joy and you will be hooked for life. Once you see green growth the hardest part is over. Then just keep your soil moist and see how fast these beauties grow.
I hope you receive your tubers soon and that you have a hundred percent success rate on getting these buggers to grow. Next month I will continue sharing what you have to do next to get the most beautiful blooms.
She who loves dahlias
Mareli