The days are getting cooler and frosts are upon us—a time to say goodbye to the last of the perennials and store away the garden tools. You may have finished deadheading and planting your spring bulbs last month, but any gardener will tell you, there is always work to be done, especially if your flower beds contain tender bulb plants.
Unlike hardier bulb plants that bloom in spring, tender bulb plants bloom in the summer. They develop and grow from fleshy storage structures like bulbs, corms, rhizomes, tubers and roots which will not survive the cold winter temperatures of northern New Mexico. The 2012 USDA Plant Hardiness Zone Map puts Santa Fe at Zone 6b; this means any plant you have in your garden should be able to handle temperatures that drop to -5 to 0°F/-20.6 to -17.8°C.
Examples of tender bulb plants include gladiolus, dahlias, lilies (callas), caladium, ranunculus, cannas, elephant ears and tuberous begonias. Not all of these plants are technically bulbs, however. The general term “bulb” is used for identification purposes. The term “tender” denotes that these plants are not winter-hardy for certain climates and will need special treatment for the next growing season.
Hardier bulb plants like tulips, daffodils, grape hyacinth, crocus and snow drops can handle frosts and do not require lifting. They can, however, spread and overcrowd, which results in a decrease in the flower size, and uneven bloom and plant height. When this occurs, these bulbs should be dug up and divided in early autumn.
Tender bulbs can survive a frost or two, if they are not hard frosts. But frost may kill any growth surrounding the bulb. If a bulb gets damaged, rot-causing organisms can enter through the damaged stem, so it is best to lift the bulbs earlier than later to avoid killing them.
How to lift and store bulbs
The following are steps for lifting and storing the most common tender bulb plants.
Gladiolus: Should be lifted before first hard frost
-Cut back foliage leaving no more than 2 inches
-If corm has attached soil, do not wash it off—this can lead to fungal problems
-Loosen soil around the base of the plant with a hand garden fork or trowel then lift by hand
-Fill a shallow box or cloth bag with dry peat moss or vermiculite and place corms, not touching
-Store the corms in a cool, frost-free location (45-50°F)
Dahlias and Tuberous Begonias: Can be lifted after first frost
-Cut back flowering stems, no more than 2 inches from the base
-Loosen soil with a garden fork, taking care not to damage which can lead to rots developing in storage
-Remove the soil from the tubers by hand. Do not wash.
-Place upside down in a cool place for a few weeks to dry off
-Fill a shallow box or cloth bag using dry peat moss or vermiculite, leaving only the old flower stalks exposed
-Store in a cool, frost-free location (50°F). Check on monthly.
Lilies: Can be lifted before or after first frost.
-Dig up using a garden fork or trowel
-Gently brush off any remaining dirt and do not wash or get wet
-Cut off foliage from the top of the rhizomes, leaving about 2 to 3 inches of the dead leaves
-Let dry. After the rhizomes have dried, place them in a paper bag or wrap them in newspaper.
-Store in a cool, dry place, somewhere that stays around 50°F
Cannas: Lift after first frost
-Once foliage is dead, dig a bit further out from where you originally planted the canna (they are spreaders)
-Remove bulbs from the ground, remove loose soil
-Cut the foliage back to 2 to 3 inches
-Gently wash the dirt off the bulbs, dry for a day or two
Fill a shallow box or cloth bag with peat moss or vermiculite leaving only the crown of the plant showing, you can also wrap in newspaper
-Store in a moist cool, frost-free place (45-50°F). Check every few weeks.
Elephant Ears: Lift before or after first frost. These can also be brought inside where they should continue to grow.
-Cut dead foliage back to 1 or 2 inches
-Wrap tubers in newspaper or place in a paper or mesh bag. Add 2-3 inches of peat moss or vermiculite.
-Store tubers in warm, dry area, but do not place tubers too close to one another
-Check on tubers every few weeks. If they are shriveling, spritz the packing medium with a water bottle to moisten, but not too much as mold can occur.
-If you find pests, use an organic insecticide
By following these steps, your tender bulbs should survive the winter in time to be planted in the spring when the soil warms up after the last frost.