Fall Bulbs to Plant: Tulips Now, Calla Lilies in Spring

Of the two bulbs we have written up, only tulips go in the ground in fall: plant them before the first frost, once the soil at planting depth stays below 60°F (16°C). Calla lilies are the opposite case. They are planted in spring after frost, and in cold zones fall is when you dig them out. This guide sorts the fall jobs for both, shows the planting months our sources give, and says plainly where they have no dates for your region.

The two bulbs at a glance

Planting tulips by soil temperature

Penn State says spring-blooming bulbs are planted in the fall, before the first frost, for an early to late spring or early summer bloom. Clemson adds the better test: daffodils go in during October or November, but tulips and other spring-flowering bulbs wait until the soil temperature at planting depth stays below 60°F. A soil thermometer at planting depth is the tool. Our when-to-plant guide has the full reasoning.

These are not national dates. Do not copy South Carolina’s calendar into a colder state.

Chilling: what the bulbs need

Tulips need a long cold period. Penn State and UW-Madison both say 15 to 17 weeks for tulips, and Penn State says the optimal chilling temperature is 40 to 45°F (4–7°C). Where the ground will not give that, Clemson says to refrigerate bulbs from the time of purchase until planting in Central and Coastal South Carolina. Keep unplanted bulbs cool rather than in a warm room.

Depth, light and animals

The three sources give three answers on depth, so pick the one that suits your bulb size.

NC State says full sun (6 or more hours) and well-drained soil. It also says mice and voles eat tulip bulbs and squirrels may dig up newly planted ones, and that tulip bulbs are toxic, so wear gloves when handling them. Our sources name no deterrent.

Tulips in pots

Clemson’s 60°F soil rule applies to pots outdoors too. For forced bulbs indoors, Clemson gives 12 to 16 weeks of cold and Penn State and UW-Madison say 15 to 17 weeks for tulips, and UW-Madison says most forced bulbs bloom three to four weeks after leaving the cold. See tulips in pots.

What is not a fall bulb: calla lily

Calla lilies are the trap for anyone shopping the bulb aisle in October. Clemson says to plant the rhizomes in spring, after the danger of frost has passed and when daytime temperatures stay above 70°F, and that they bloom 60 to 90 days later. Planting depth is 3 to 4 inches (8–10 cm) with the growing tips up, and 12 to 18 inches (30–45 cm) apart (Clemson, Penn State). Fall is not the planting season for them, and our sources give no advice on fall-planting a calla.

Lifting calla lilies in cold zones

Where callas are not hardy, fall is the time to lift them. Clemson says they are winter hardy in zones 8 to 10. NC State says the white calla is hardy to zone 8 and can survive in zone 7 if protected, and that in cooler climates you should provide thick mulch and be prepared to dig the corms.

1. Wait for the leaves to die back, or the first frost. Penn State says to dig after the leaves have died back or after the first frost.
2. Trim the foliage. Leave an inch or two (2.5–5 cm) of stem (Penn State).
3. Dry the rhizomes. Penn State says to let them dry in a warm area for several days.
4. Store them cool. Penn State says to keep them in a cool place, out of reach of children and pets, because the rhizomes are poisonous.

Our sources give no storage temperature or packing material. The calla overwintering guide covers the zone conflict and a pot alternative.

A fall order of jobs

1. Check the soil thermometer at planting depth before opening a bag of tulips.
2. Plant tulips once it reads below 60°F, and before the first frost.
3. Dig callas when the leaves die back or after the first frost, if you are in a cold zone.
4. Dry and store the rhizomes, labelled and out of reach.
5. Leave other plants alone. Our hydrangea fall care guide says not to prune bigleaf types now.

Bulbs we have not covered

Clemson names daffodils as an October or November planting, but we have no daffodil guide and give no daffodil advice. For a wider fall list, read flowers to plant in fall. To see when each plant flowers, use the bloom calendar.

What our sources do not tell you

They give no dates for tulip planting outside South Carolina, no weeks-before-frost figure, no advice on spring-planting tulips or fall-planting callas, and no storage temperature for callas. The 60°F soil rule is Clemson’s alone.