Gardening Laidback Gardener Tip of the Day

Storage Temperatures for Tender Bulbs

At what temperature should you store your tender bulbs? Source:

You’ve brought your tender bulbs (gladioli, tuberous begonias, dahlias, cannas, caladiums, etc.) in for the winter? Perfect! The bulbs are either in their original pot or bare root, surrounded by peat, vermiculite, newspaper, etc. Also perfect! Now where to place them for the winter?

On the Cold Side

The ideal location for winter storage is cool, but not cold, between 40 and 55 °F (5 to 12 °C). That means a refrigerator or a root cellar is generally too cold for bulbs, but a barely heated basement or protected garage ought to be ideal. At such temperatures, there will be little evaporation and that will allow the bulbs to stay dry yet well hydrated until spring. There should be no need to humidify them in any way.

On the Warm Side

You don’t have a cool spot where you can store your bulbs? I don’t either … and that’s not a problem! You can easily store them at room temperatures as well. However, warmer air means there will be evaporation and probably some dehydration. That means you’ll have to take an extra step and moisten them occasionally through the winter.

I recommend a monthly inspection, followed by rehydration if needed.

How to handle this inspection, though, depends on how the bulbs are stored.

In Pots or Loose

For example, I store many of my tender bulbs in the same pot they grew in all summer. If so, you can’t really examine the bulbs themselves, but you can take a look at the soil. If it’s very dry, add just a dribble of water, say a few teaspoonfuls, to the top. Let the water penetrate the potting soil (that may take a few minutes, as very dry potting soil will repel water at first), then store the pot away again.

If .loose bulbs (here, dahlia roots) look dehydrated, simply spray lightly with plain water. Source:

If the bulbs are loose (bare root), you really can inspect them individually. If they don’t look shriveled (often the case during the first months of storage), they’re doing fine: just put them back. If, on the other hand, they’re turned soft or starting to shrivel, just spray them with clear water and put them back into storage. This tiny amount of water will be enough plump them up again and prevent a potentially fatal dehydration.

A Reminder

Add “check bulbs monthly” to your agenda. Source:

As soon as you bring your tender bulbs indoors in the fall, add a monthly note to your agenda: “check dormant bulbs, moisten as needed.” Mine is electronic, so beeps at me to let me know when it’s time. You don’t have to be precise: check them a week early or a week or two late, but do give them a look-over.

As you can see, when tender bulbs are dormant, they’ll adapt to almost any non-freezing situation. Finding the right place to store them couldn’t be simpler!

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