Common Disease Problems
Corm Scab: Watersoaked spots appear on corms (bulbs). Leaves turn yellow and die prematurely. This disease may be spread by bulb mites. Burpee Recommends: Remove and destroy infected corms. Control bulb mites.
Mosaic Virus: This can cause flower petals to have broken or streaked colors. Burpee Recommends: Dig up and discard affected plants. Do not use tools on other plants until they have been sterilized. Control aphids, which can spread the disease.
Spotted Foliage: This can come from late frosts after the foliage was emerged. Burpee Recommends: If a frost is expected cover the plants overnight. Be sure to mulch the blubs in fall after the ground freezes.
Common Pest and Cultural Problems
Aphids: Greenish, red, black or peach colored sucking insects can spread disease as they feed on the undersides of leaves. They leave a sticky residue on foliage that attracts ants. Burpee Recommends: Introduce or attract natural predators into your garden such as lady beetles and wasps which feed on aphids. You can also wash them off with a strong spray, or use an insecticidal soap.
Bulb Mites: Shiny creamy white mites range from .5 to 1 mm long and appear in clusters. They infest bulbs in storage and in the field. They damage bulbs by penetrating the outer tissue layer which eventually causes the bulbs to rot. Burpee Recommends: Inspect bulbs before planting and do not plant damaged bulbs. Avoid damaging bulbs when planting or weeding. Remove plant debris after leaves die back.
Bulb Nematodes: Microscopic worm-like pests that live and reproduce inside the bulb, feeding on the stems, leaves and bulbs. It can live for several years in the soil. Burpee Recommends: You can have your soil tested by your local Cooperative Extension Service to see if you have nematodes. Do not plant into infested soil and do not plant related crops into the soil for several years.
Slugs: These pests leave large holes in the foliage or eat leaves entirely. They leave a slime trail, feed at night and are mostly a problem in damp weather. Burpee Recommends: Hand pick, at night if possible. You can try attracting the slugs to traps either using cornmeal or beer. For a beer trap, dig a hole in the ground and place a large cup or bowl into the hole; use something that has steep sides so that the slugs can’t crawl back out when they’re finished. Fill the bowl about ¾ of the way full with beer, and let it sit overnight. In the morning, the bowl should be full of drowned slugs that can be dumped out for the birds to eat. For a cornmeal trap, put a tablespoon or two of cornmeal in a jar and put it on its side near the plants. Slugs are attracted to the scent but they cannot digest it and it will kill them. You can also try placing a barrier around your plants of diatomaceous earth or even coffee grounds. They cannot crawl over these.
Squirrels and other Rodents: Squirrels, chipmunks and voles dig up bulbs and eat flowers as well. Burpee Recommends: A physical barrier is the best control of rodents. Place a cylinder in the ground around the bulbs with the top level with the soil. Cover bed with screening or hardware cloth.
How can I force my crocus to bloom inside? In order to force hardy bulbs such as crocus, you need to give it the conditions it would have experienced if it were planted in the garden. Fill a container with soil and plant the bulbs, cover with ½ inch of soil. Bulbs can be fairly close together, 12 bulbs will fit in a 6 inch pot. Water thoroughly and label with the date of planting. Place the pot in a cool, frost-free location, about 35-45 degrees F, outside or even a refrigerator. Bulbs will need about 12 weeks of cold to be ready to bloom. Check regularly; do not allow to dry out. Water when the soil approaches dryness. After 12 weeks, slowly expose bulbs to warmer weather and brighter light. Bring into a bright cool room, 55-65 degrees F, water and use a half strength houseplant fertilizer. When the foliage emerges move to a sunny window and warmer temperatures. After bloom is over, keep the foliage growing and when it dies back you can store the bulbs to plant in the garden. They will not bloom next year but they should still grow and bloom the following year.
Can I force my bulbs to bloom every year? No, bulbs may be forced one time, but not in future years.
Can I grow crocus in a container? Yes. Make sure it has excellent drainage and protect it in winter as the bulbs are more exposed in containers than in the ground. If it is a dry winter you may have to water the container. Crocus are happiest in the ground, however, and will multiply for years if they are well sited.
Do deer bother crocus? Deer do not generally tend to bother crocus, although they may if they are very hungry.