Fall care for tender and hardy bulbs

August 20, 2020

“Bulbs” is a general term gardeners use when referring to true bulbs, corms, tubers, rhizomes, and tuberous roots. All of these are storage structures for plants and hold nutrients and water to support the plant during the growing season and through dormancy in winter.

With fall right around the corner, it is important to take care of bulbs planted in your garden, under trees, in containers and in your lawn.

Some bulbs are tender and require removal and storage over the winter while others are hardy and can withstand our cold winters. Here are tips for caring for both hardy and tender bulbs this upcoming fall.

There are two types of bulbs

Tender bulbs

Planted in the spring for summer blooming
Amaryllis, canna, gladiolus, begonia, dahlia, colocasia (elephant ears), caladium

Grey square planter planted with purple and pink annual flowers, a plant with broad green leaves and a maroon-leafed tree against a beige wall with lawn in the background. — Elephant ears (Colocasia) with blooming summer annuals and a Japanese maple tree

Hardy bulbs

Planted in the fall for spring blooms
Tulip, daffodil, lily, Hyacinth, crocus, iris, snowdrops, Allium, glory of the snow, Fritillaria, grape hyacinth

Maroon bell-shaped drooping flowers in green grass-like leaves. — Fritillaria meleagris

Cluster of purple and white small flowers with thin green leaves growing out of dry brown leaves on the ground. — Crocus are some of the earliest spring bulbs

Caring for tender bulbs

Digging up

Dig tender bulbs in the fall after foliage turns yellow, dries up or is killed by frost, about 6 to 8 weeks after bloom.
Loosen the roots gently with a garden fork or spade by digging several inches away from the base of the plants to avoid cutting off the roots. When digging up larger plants, loosen the soil on all sides as well.
You want to make sure to avoid cutting or breaking the fleshy structure as diseases can easily contaminate plants through cuts and bruises causing rot and even death.

Cleaning tender bulbs

Some plants such as dahlias are best washed gently with a hose.
For garden cannas and dahlias, you can put hardware cloth or mesh across the top of a large garbage can and set a clump of dahlias or cannas on top of it, then wash the soil into the garbage can. This eliminates mess and the soil and water can be returned to the garden.
Gladiolus bulbs are best left unwashed and just allowed to dry. After drying, the soil may be gently removed.

Flower bed with tall, broadleaf coppery green leaves in the center, surrounded by yellow, orange and purple flowers with a grey stone wall in the background planted with a garden above. — Tropicana canna lilies have dramatic copper-colored, striped foliage and orange flowers

Curing or drying tender bulbs

The typical drying period for most species such as dahlias, cannas and callas is one to three days depending on temperature.

Curing should be done in a room or area away from direct sunlight or drying winds.
The temperatures for curing should be around 60-70℉.
Gladiolus require long-term curing for about 3 weeks.

Label bulbs

You can label bulbs before storage by writing directly on the fleshy root (one or several roots) with a felt marker.
Or tie wood and wire tree labels to a root.
Make sure to put the cultivar name or important characteristics on it.

Storing tender bulbs

Store the bulbs in cool, dry conditions, and an average of 40℉. Certain tender bulbs need to be stored at specific temperatures such as the Peruvian Daffodil at 60-65℉ and Tuberose at 55-65℉.

Store only large, healthy bulbs.
Avoid storing bulbs that are damaged or too small.
Damaged bulbs may rot and small bulbs may dry up.
Check stored bulbs periodically and remove any that are damaged or rotting.

Caring for hardy bulbs

Round-headed purple flowers on narrow green stems growing amidst ferns with an evergreen tree in the background. — Alliums like ‘Globemaster’ are ornamental onions and provide great texture and form

Hardy bulbs require a period of cold temperatures (think winter) in order to break dormancy and start flowering. These bulbs are perennial and thus left in the ground year after year. With good conditions, they will bloom every spring.

Every three to four years, hardy bulbs should be dug up in the fall, divided and replanted.
Rotting or dried up bulbs should be composted.
New bulbs may be added at this time as well.

Prepare for winter

Water hardy bulbs until the soil freezes. This prevents the bulbs from drying out over the winter. Before watering, feel the soil a few inches down. If it’s dry, water to saturate the soil.
Bulbs grow well in loamy, well-drained soil. Sandy soil requires more water than heavier soil and compacted water will prevent water from seeping into the ground.
Amend soil with compost before planting hardy bulbs.

Moving hardy bulbs

If hardy bulbs must be moved before fall, wait until the foliage has yellowed and withered.
Carefully dig up the bulbs and gently shake off loose soil.
Discard small bulbs and store the remainder in a cool, dry, well-ventilated place until fall planting time.

For more information on planting spring bulbs this fall, see Planting bulbs, rhizomes and tubers.

Eliza Carlson, Stearns County Extension intern, and Julie Weisenhorn, Extension horticulture educator

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