new tubers

What to do with your new Tubers

Thanks to Katie, for this question, “I’m new the the MN Dahlia Society and the tuber sale. I just picked up my tuber order yesterday. Thank you so much to you and all the other volunteers for doing the sale — it’s so wonderful!
I did wonder, being a novice dahlia grower and new to the tuber sale, what should I do with my tubers? “

The tubers you have received now, were in storage at temperatures around 45 degrees Farenheit, until less than 2 weeks ago. But in order to wake them up and inspect them, they have been warmed up a bit. You do not want to return them to cold temperatures gain because that could stop or upset new plant growth.

  1. Get your new tubers into a warmer environment (50 – 60 degrees) than the garage or sun porch.

[If tubers are too moist they will rot or develop fungus (usually white, which should be scrapped off) but at this time the more common issue is drying out. If the tubers look a bit wrinkled then you need to increase the moisture quickly. One way is, to to put a damp cotton ball in a sealed bag with them, until they start to look better.]

  1. Tubers should be put into any medium to stabilize the moisture content to keep them from drying out. There are many ideas about this; but the traditional method is wood shavings.

[They don’t need light or fertilizer until sprouts appear. Sprouts are white until they grow out of the medium and reach the light, then they turn green.]

The average Last Frost Date here is May 10th. This is why we usually recommend planting tubers outside after Mother’s Day. You should ensure that the soil is at least 55 degrees and not too wet (saturated) from recent heavy rains.

Tubers can be potted now for transplant after last frost. Soil should be deep enough that it does not dry out.

Starting them early will result in early blooms but they will continue blooming until the first frost in fall. The only concern is for those that enter their blooms in competition because the first blooms are usually the biggest, so they try to time them for the show.

It will take potted tubers, a week or two for sprouts to form. With good light and moisture the plants can grow to 12 to 16 inches by May planting. Leaves should be dark green and robust; not yellow and spindly, to get the full potential out of them when put into the garden.

Planting Trays

If you don’t have a good place to pot and grow them that large, you can wait till May 1st and just plant them in plastic trays. This will give your plants about 2 to 4 inches of leaves with some good root structure.

Be careful at this point to protect new roots and plants from drying out.

5 thoughts on “What to do with your new Tubers”

  1. Hello! Wondering if there is any information on how to properly pot dahlias inside for outdoor planting later in the season when the soil warms up. Thanks!

    1. There are a couple articles on our home page. Between them, you should find what you need.
      What to do with your new Tubers
      Planting Dahlias Presentation Recap
      Planting Dahlias

  2. Kathleen Moore

    I think I have powdery mildew and possibly some blight. It’s not all over but I think I should spray. I have Daconil, Neem, and Immunox. I’ll wait to get more info before applying. I have 2 large beds so spraying is probably the best and easiest on my back!

    1. Hi Kathleen, I would suggest Eagle fungicide that can be bought at Do My Own Pest Control (, for plants showing any powdery mildew. Daconil and Immunox are ok too. Eagle is compatible with most other sprays. Spray at two week intervals. Spray in the evening in cooler weather or run the risk of burning the plants. If someone wants an organic solution they could use Stylet oil but this is best used before there is a problem and must be done in cooler weather in the evening as the oil clogs up the plant pores and will cause burning. Wear protective clothing and mask when spraying chemicals, following directions, and spray early morning or evening to help beneficial insects from getting hurt. John K.

  3. Kathleen Moore

    Thanks so much for this advice. It’s hard to know what to do. I just sprayed with Immunox and they seem to be doing better.
    Kathy M.

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