Crocuses must experience a period of cold weather to bloom, so plant them in the fall for spring blooms.
Before the ground freezes in the fall, crocus tubers can be planted almost anywhere, except in the dense shade on the north side of buildings or under thickets.
Ideally, plant crocus tubers 6 to 8 weeks before a hard frost is expected in the fall and when soil temperatures are below 60°F (16°C). This is usually during September or October in the northern United States and Canada, and October or November in the southern United States.
How to plant crocuses
Plant crocus tubers 3 to 4 inches deep (with the pointed end up). After planting, water well.
Plant bulbs in groups or clusters rather than placing them in a row along a path or border. Single flowers get lost in the landscape. Plant a few inches apart and plant in groups of 10 or more.
Consider planting crocuses in lawns and meadows where they can form carpets, or mash them into the front of flower beds along the edge.
GROWING
Apply a balanced fertilizer in early fall if your spring is short and the days warm up quickly; or apply fertilizer after the bulbs have bloomed in late winter if the spring is long and temperate. The crocuses will have a chance to use the extra nutrients to produce larger carbohydrate stores.
During the fall, keep crocus beds watered if the weather turns dry, but don’t drench the soil. Cover the beds with compost before winter.
In late February, remove heavy mulches from snowdrops and crocuses so the shoots can come through. Leave a light layer of leaves to provide protection from late-season frost.
In February and March, keep plastic milk jugs or other covers on hand to protect the blooms of crocuses and other early bloomers against the return of severe weather.
If you have crocuses growing in your lawn in mid-spring, don’t mow until their leaves have died down.
RECOMMENDED VARIETIES
‘Bowles White’ produces white flowers with deep golden yellow throats in early spring. It grows 2 to 3 inches tall.
‘Flower Record’ has single pale violet flowers in spring to early summer. It grows 4 to 5 inches tall.
‘Pickwick’ is a striped crocus with alternating pale and dark purple and dark purple base. It is 4 to 5 inches tall and blooms in spring to early summer.
‘Tricolor Crocus’ is a beauty. Each narrow flower has three distinct bands of purple, white and golden yellow. It grows 3 inches tall and blooms in late winter and early spring.
‘Purpureus Grandiflorus’ has profuse violet flowers with purple bases. It grows 4 to 5 inches tall and blooms from spring to early summer.