Daffodils and crocus are all classed as spring bulbs even though crocus is technically a corm not a bulb. The difference is like the difference between a head of garlic and an onion. Both grow daughter segments around the mother bulb and when there are a lot of smaller segments the energy of the plant is diverted to support that development rather than produce a flower. The result is that green leaves come up as normal in spring, but very few flowers are put out. The remedy is to divide the bulb and space them out so that they flower again next year.
In daffodils and tulips, which are true bulbs, the offsets are grown around the main bulb and the new shoots emerge vertically from that segment alongside the parent shoot. As the years progress, the offsets completely surround the mother bulb.
In corms, the cormels form around the base of the mother corm. Each little pea shaped cormel stays attached to the main corm while it matures and grows. The cormels eventually separate from the parent.
To divide the bulbs and corms, wait until the green leaves have started to turn brown and then cut the decaying leaves off. Dig the bulbs up and rinse carefully. The offsets and cormels are usually apparent and some segments will drop off when you lift the bulb. Others can easily be pulled off with your fingers leaving a single bulb again, and lots of smaller bulbs. Replant the bulbs in new places in the garden and by next year all but the smallest segments will grow and flower for you.
It is not necessary to wait until the whole mass of bulbs are so overgrown that they show declining flowers and most bulbs benefit from being divided every three to five years just as your other perennials do. Of course if you have an especially beautiful daffodil that you want to share with your friend, you can do that too once the bulb is mature and has a few offsets or cormels set.
Examples of true bulbs are daffodils, tulips and ornamental alliums;
Examples of corms include crocus and gladiolus.
How to Sow
Planting Bulbs in Fall:
- Because your bulbs will probably be left where you plant them for several years, good soil preparation is highly desirable. Crocus grows best in full sun to light shade in a light, well-drained soil enriched with organic matter. Loose, crumbly soil beneath a bulb encourages good growth and promotes drainage; it is a good idea to prepare the soil at least a few inches deeper than the recommended planting depth. Check the proposed site for standing water after a rainfall. If you must plant where the soil is known to remain wet, raise the soil level by 6-12 inches above the surrounding soil.
- It is a good idea to add fertilizer, such as bonemeal, when you prepare the soil. Be sure to mix the fertilizer into the soil so it does not come into direct contact with the bulbs.
- The general rule for planting is to cover the bulb with soil to 2 to 3 inches of soil. In very cold climates, or where the soil is very light and sandy, plant a little deeper. In heavy soils, or in areas with a high water table, plant slightly more shallowly. Plant all bulbs of a kind, when grouped together, at the same depth so they will bloom at the same time and attain the same height.
- For planting clumps of bulbs in beds and borders, dig a hole large enough to hold all the bulbs in one group or drift. Set them upright at the bottom of the hole, tops up (pointed side up), and space properly. Press the bulbs into the soil and cover with the prepared soil to the recommended depth. Crocus is most effective when planted in masses.
- Crocus should be planted 1-2 inches deep, 2-3 inches apart.
- After planting water thoroughly to settle the soil and to encourage the start of root growth. Sufficient moisture is vital to the health of your bulbs; lacking ample rain, it may be necessary to water new plantings once a week in fall. The roots will continue to grow in fall until the soil freezes.
- Be sure to mark where you planted your bulbs so you know where they are in spring.
- Add 1-3 inches of mulch for winter protection after the ground freezes.
How to Grow
- Flower bulbs also require watering after blooming, while the foliage is ripening. Water weekly if conditions are dry.
- In spring after flowering, do not cut the foliage off; the foliage is part of the perennial growth cycle. Allow it to die back naturally.
- Apply a fertilizer after the plants have finished blooming.
- Crocus can be left undisturbed for many years and will multiply.
- Some varieties bloom in fall rather than spring.
- Crocus is easy to force for indoor blooms.
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.