Crocuses are small, spring-flowering corms that herald the end of winter with their cheerful, low-growing blooms. While these cold-hardy plants are often left in the ground to naturalize, storage becomes necessary when dividing overcrowded clumps, relocating them, or gardening in climates too warm for the required natural chilling period. Proper storage ensures the underground structures remain healthy and retain the energy they need to produce vibrant flowers the following season.
Preparing Bulbs for Dormancy
Preparation for storage begins only after the foliage has completely died back and turned yellow, which typically occurs in late spring or early summer. Waiting for this natural decline is paramount because the leaves are actively photosynthesizing and transferring energy back into the corm for next year’s bloom. Once the leaves are fully withered, carefully lift the corms from the soil.
The lifted corms must be thoroughly cleaned of any clinging soil or debris, but they should never be washed with water. After initial cleaning, the corms require curing, which is drying them out to prevent rot and fungal growth during storage. Spread the corms in a single layer on a screen or cardboard in a dry, dark, and well-ventilated location for about seven to ten days. This period allows the outer layers to harden and seal in moisture.
Following the curing period, inspect each corm for any signs of damage, soft spots, mold, or insect infestation. Discard any corms exhibiting these problems immediately to prevent the spread of disease. If the corms were dug up for division, gently separate the new corms from the shriveled remains of the old ones. Keeping only the largest, healthiest corms ensures the best possible display for the upcoming season.
Setting Up the Storage Environment
The storage location needs a cool, consistent temperature to keep the corms dormant. An ideal temperature range for crocus corm storage is 50 to 60 degrees Fahrenheit (10 to 15.5 degrees Celsius), as temperatures above 70°F can cause damage or premature sprouting. The space must also be dry and dark to inhibit mold growth.
The corms should be placed in containers that allow for consistent air circulation to prevent moisture buildup. Suitable containers include mesh bags, perforated cardboard boxes, or ventilated crates. Avoid using sealed plastic bags or non-breathable containers, which trap humidity and invite fungal issues. For added protection, the corms can be layered in a breathable storage medium such as dry peat moss, vermiculite, or newspaper shreds, ensuring they do not touch one another.
Selecting a location like a cool pantry, a dry cellar, or an unheated garage will often meet the environmental requirements necessary for successful dormancy. It is important to ensure the storage area is kept away from ripening fruits, such as apples or pears, which naturally release ethylene gas. Exposure to this gas can prematurely trigger aging in the corms, reducing their viability and flower quality.
Ongoing Care and Inspection
During the storage period, which generally lasts until the fall planting season, the corms require periodic inspection to maintain their health. Plan to check the stored corms at least once a month, looking carefully for any visual changes that might indicate a problem. Signs of trouble include fuzzy, white, or green mold, foul odors, or a soft, mushy texture when handled.
If a small amount of mold is detected, the affected corm should be removed and discarded immediately to prevent contamination of the entire batch. A light dusting of a fungicide powder can also be applied to the remaining corms to offer a protective measure against further fungal development. If the corms appear to be shriveling or overly dry, the humidity of the storage medium can be slightly increased by adding a small amount of lightly dampened peat moss to the container.
Conversely, if the corms are damp or show signs of sprouting, the storage conditions are likely too warm or humid, and better ventilation is needed. Once the appropriate planting time arrives, typically in the fall before the ground freezes, the corms can be removed from storage. Check them one final time for firmness and health before planting them back into the garden for their chilling period, which is necessary for spring blooming.