Saving and Storing Tender Bulbs

November is a good time to dig and store summer “tender bulbs” like dahlias, cannas, and gladioli.  Because of their tender nature these plants require special attention, but if given the special treatment they require, they will reward you with blooms for years. The term "tender bulb" refers to plants which have fleshy storage structures (bulbs, corms, tubers, and roots) which are killed by our cold winters if not brought indoors. Special protection, such as digging and bringing the fleshy storage structure into a warmer area for storage through the winter months is required.

The tender bulbs should be dug after the foliage dries up or is killed by frost, and before the ground freezes.  In our area this is usually in the late October to early December time frame.

It is important to loosen the roots gently with a fork or spade, digging several inches back from the base of the plants so that the roots are not cut off unnecessarily. Loosen the soil on all sides of the plant before lifting the clump of roots and soil. In all cases, avoid cutting, breaking, or "skinning" the fleshy structure. Diseases enter through cuts and bruises very readily and can cause rotting and losses in storage.  Brush off any excess soil.  In the case of dahlias, look for strong tubers with “eyes” - A tuber will not sprout next spring unless it has at least one "eye." These are the growing tips for next year, and look similar to the “eyes” on a potato.  The eyes are typically found at the top of a tuber on the ridge where the tuber joins the stem.

The key factors in storing the tender bulbs are temperature, moisture, and darkness.  A temperature range of 35-50 degrees works well, making an attached garage, or unheated basement or root cellar ideal.  They should be kept dry, but not allowed to dry out completely.  Surrounding them in peat, vermiculite, or sawdust is a good way to achieve this.  Keep them out covered and away from light during their winter dormancy.

Remember to periodically check stored bulbs, tubers, and roots during the storage season. Remove any damaged or rotting material. In cases where tuberous roots like dahlias have some rot occurring, cut back until you reach clean white, fleshy tissue again. Remember that these structures are living plants and as such may need attention and care even during their dormant period.  If they appear to be too dry – shriveling, for example, moisten the packing material slightly with a mister or spray bottle.