How to Store Tubers in Sphagnum Moss | Winter Storage of Tuberous Begonias

Saving your own begonia tubers from season to season is not only cost effective but also ensures that you will have begonias in the early spring. Most seed mail order companies don’t ship tubers until early May. This very late start could delay begonia flowering by a couple of months, limiting your summer enjoyment.

Red Begonias indoors by window

Project Difficulty


Mosser Lee
Products Needed

What You Will Need

1. Cardboard Box
2. Mesh Bag (fruit or vegatable bag)
3. Gloves
4. Sissors or Small Knife


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There are some wonderful uses for sphagnum moss for keeping your bulbs and tubers safe over winter. For this tutorial we will store tubers from the begonia plant. In Zones 4-7, tuberous begonias need to be dug and brought in for the winter.  The dormancy and proper curing of the tuber root system during the off-growing season is critical for the next year’s growing success. Making sure you have ensured the Winter Storage of Tuberous Begonias will really pay off when you plant in the spring.

Instructions on How to Store Tubers

1.  Dig up the tuberous begonias within a few days of a killing frost, leaving soil around each tuber.  Cut off the stems about 1 inch above the tubers.  Cure the tuber by placing them in a cool, dry area for 2 to 3 weeks.  Then remove the dry soil attached to each tuber.

2.  Store tubers in a mesh bag with an identification tag for either the plant name or color of the flower.  This will help you in arranging your plantings in the spring. Place about 2” of dry loose Mosser Lee long-fibered sphagnum moss in the bottom of a cardboard box and carefully place the bagged tubers on top of the moss making sure the tubers are upright and not touching one another.

Store tubers in a cardboard box and sphagnum moss

3.  Cover the tubers with another 2” of dry long-fibered sphagnum moss. Mosser Lee long fiber sphagnum moss provides good air circulation about the tubers.

4.  Since begonia tubers are very susceptible to fungus and rot, leave the top of the box open.  Even though long-fibered sphagnum moss is excellent at absorbing moisture, leaving the box open allows the air inside and outside of the box to equalize and ensures that no moisture is being trapped in the box. After a couple of weeks, fold the box top closed and place it in a dry space where the temperature will stay in the 40°F – 50°F range.  Hint: Check the box every couple of weeks to make sure the tubers are dry and no fungus has started to grow.  The tubers must not be allowed to freeze.

removed store tubers in the spring

Preparing Tubers for Spring Planting

5.  In the early Spring, about 2 months before the begonias can be planted outside (Planting is usually after the last frost), remove the stored tubers from the box and place in a warm location. You can use a heat mat if you have one.  This should help them break dormancy.  When you see growth starting at the top of the tuber, pot them and keep them in a sunny, warm location. They can be transplanted when they show early flowers. 

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