Tuber Start

Planting Dahlias Presentation Recap

At our May General Meeting, we were given a presentation on planting dahlias by John Kooiman and Larry Bagge who shared their methods and expertise. Here are some notes and takeaways from the presentation.

Planting Presentation

  • Many growers start their tubers indoors before planting them in the ground. This allows you to know what you have growing before dropping your tubers in the ground.  Tubers can be placed in pots or trays with potting soil with the eye(s) pointed up. Water your tubers when sprouts are above the soil and don’t allow the soil to become saturated which will cause tubers to rot.


  • Do not plant your tubers until ground temps have reached 60 degrees. In general, it is safe to plant your dahlias when you plant your vegetable garden. Cool weather and rain will cause tubers to rot in the ground.


  • When planning the layout of your dahlia garden, keep in mind each plant will need a minimum distance of 2 feet of space between each plant. This allows for air circulation, ease of access to work on the plant, and prevent the plants from fighting for growing space.


  • Both John and Larry use no-till or low till methods on their established gardens. Tilling can cause compaction of the soil by destroying the soil structure and disrupting the natural microbial ecosystem of the soil. However, both of them make sure to add lots of organic matter to their garden beds by top-dressing or by light/shallow cultivation of the soil.


  • Be sure to water your plants before planting them out in the garden. Dig a hole about 6 inches deep and large enough to fit the root system. At this time you should add a slow release (granular) fertilizer/amendment to the planting hole. Some growers use bone meal, earthworm castings, or a bulb and bloom fertilizer. Mix the fertilizer lightly with some of the soil and place your tuber in the hole.


  • Some growers will plant their tubers horizontally in the ground and some will angle the tuber in the hole with the root system resting at a lower point than the shoot.


  • Plant your tuber so that the sprouts are oriented South and the tuber and root system are oriented North.


  • There are many different ways growers support their dahlias. However, be sure to always place your support system at the time of planting to prevent accidentally piercing the tuber or its root system. The method you choose to use all depends on the number of plants you have, the time you want to spend on your plants, and what works for your budget. John discussed his method of staking his plants in conjunction with a heavy duty tomato cage. This method reduces the amount of tying needed for his numerous plants. The stake allows him to tie up his plants when they reach above the tomato cage.


  • When choosing your materials for supporting your plants, be sure to use sturdy materials. Rebar is a top choice for staking dahlia growers. Rebar is cost-effective, sturdy, and lasts for several decades (unless you live by an ocean).


  • Protect your young sprouts from rabbits and squirrels. These garden pests love the tender young shoots. Many growers buy rolls of chicken wire and create “cages” or cloches until plants are more mature.





4 thoughts on “Planting Dahlias Presentation Recap”

  1. Michael Newman

    I have always wondered what to do when I take my dahlias out of storage and some already have two to three inches of growing shoots. I try to handle them very carefully and plant them so the new growth is just under the soil.
    Is this the right thing to do?
    Mike in Minneapolis

    1. For 1 or 2 inches, I think that is fine. I have seen some tubers, that were forgotten, with much longer sprouts and I would go ahead and cut them down to an inch or so. They will grow back. Even if the sprout gets broken at the eye, it should grow back. But for the length you are seeing, the only critical depth is for the tip of the sprout – which should be just below the surface on the north side of the stake. Since you have a little length, I would bend the sprout down and then up so that it is coming up right against the stake.

  2. Is there any advice on planting tubers in pots that are then planted in the ground to make lifting the tubers easier in the fall? How big of pot would be necessary? Would it get enough drainage? Would you use potting soil or regular garden dirt? Or would you just not do this method?

    1. Last year I used both air pots and fabric bags to grow dahlias. The air pots were great because at the end of the fall, I just had to remove the plastic screws with my fingers (no tools) and the dirt fell away leaving the tubers easy to clean-up with no digging. The bags were not as easy because I had to dump the root ball out of the bag without damaging it. I bought the 12 gallon pots for large dahlias and 7 gallon for smaller varieties, on amazon. Here is my short video:

Comments are closed.