Caladium: Tender Bulbs
How to Sow and Plant
Planting Caladium Bulbs
- Plant bulbs outside after all danger of frost has passed and daytime temperatures remain above 70 degrees. Caladiums are tropical plants and cannot tolerate any frost and only emerge when the soil is warm.
- Select a location in shade or part sun with a good rich moist organic soil.
- Prepare the bed by turning the soil under to a depth of 8 inches. Level with a rake to remove clumps of grass and stones.
- Most plants respond well to soils amended with organic matter. Compost is a wonderful form of organic matter with a good balance of nutrients and an ideal pH level, it can be added to your planting area at any time. If compost is not available, top dress the soil after planting with 1-2 inches of organic mulch, which will begin to breakdown into compost. After the growing season, a soil test will indicate what soil amendments are needed for the following season.
- Plant bulbs 8-12 inches apart. The knobby side should be up as these are the growing points.
- Cover with 1 inch of soil.
- Bulbs may be started inside 6-8 weeks before all danger of frost has passed. They require a warm soil in order to emerge so consider using a heat mat.
How to Grow
- Keep weeds under control during the growing season. Weeds compete with plants for water, space and nutrients, so control them by either cultivating often or use a mulch to prevent their seeds from germinating.
- Mulches also help retain soil moisture and maintain even soil temperatures. For annuals an organic mulch of shredded leaves lends a natural look to the bed and will improve the soil as it breaks down in time. Always keep mulches off a plant’s stems to prevent possible rot.
- Keep plants well-watered during the growing season, especially during dry spells. Plants need about 1 inch of rain per week during the growing season. Use a rain gauge to check to see if you need to add water. It's best to water with a drip or trickle system that delivers water at low pressure at the soil level. If you water with overhead sprinklers, water early in the day so the foliage has time to dry off before evening, to minimize disease problems. Keep the soil moist but not saturated.
- After new growth appears, a light fertilizer may be applied. Keep granular fertilizers away from the plant crown and foliage to avoid burn injury. Use low rates of a slow release fertilizer, as higher rates may encourage root rots. Caladiums benefit from a granular fertilizer every 2-3 weeks.
- Monitor for pests and diseases. Check with your local Cooperative Extension Service for pest controls recommended for your area.
- Many gardeners remove any flower stalks that develop to keep the strength in the plant.
- Caladiums are only hardy in zone 10. In other locations in the fall before frost or when the foliage begins to die back, dig up the bulbs with the soil and tops clinging to them. Let bulbs dry inside, out of direct sun with plenty of air circulation. Remove the leaves when they are easily tugged away from the bulb, shake off the soil, do not wash. Store bulbs in dry peat moss, perlite or vermiculite. Do not store the bulbs below 60 degrees.
- Caladiums are great for brightening shady areas.
- Caladiums are ideal for containers, including windowboxes.
- Caladium foliage adds drama to cut flower arrangements.
Common Disease Problems
Bacterial Leaf Spot: First signs are small translucent spots with a broad yellowish edge that slowly enlarge and become angular or irregularly circular with a reddish center. It thrives in cooler temperatures. Burpee Recommends: Remove infected plants and do not plant in the same location next year. Avoid overhead watering. Do not work around plants when they are wet.
Fusarium Wilt: is one of the most damaging plant diseases because of its spread during periods of hot weather. The first symptom of fusarium is the appearance of a few yellow leaves or a slight drooping of the lower leaves. Caused by a soil-borne fungus, the fungus enters through the roots and passes up into the stem producing toxic substances. Burpee Recommends: Destroy affected plants at the first sign of fusarium and rotate crops.
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 who feed on aphids. You can also wash them off with a strong spray, or use an insecticidal soap.
Caterpillars: There are various caterpillars that feed on caladiums making holes in the foliage. Burpee Recommends: Pick off and destroy or collect for birds.
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.
Sunscald: Leaves are bleached and faded, often turn white with brown crispy edges. There are no signs of pests and diseases. Plants were usually recently moved. The bright light and heat from the sun break down the chlorophyll which leads to death of the leaf. Burpee Recommends: Transplant caladiums to a spot that has more shade in the afternoon. Do not place caladiums in a south or south-west exposure.
Do caladiums produce flowers? Yes, but the flowers are usually hidden by the colorful foliage. Many gardeners remove them to keep the strength in the plant.
Can I start caladiums inside? Yes, caladiums tend to emerge fairly late in spring, even early summer, when planted directly in the garden so many gardeners prefer to start them early indoors. Start them about 6 weeks before last frost. Plant one inch deep in pots large enough to accommodate the bulbs, use a good quality potting soil. Keep the soil barely moist but not wet. A heat mat can make them emerge more quickly.
Why are my caladiums short? Stunting can occur if the bulbs were stored in a cold place. Make sure the bulbs are stored above 60 degrees. Never allow bulbs to freeze.
Why haven’t my caladiums emerged? I planted them four weeks ago. Caladiums tend to emerge late because the soil must be thoroughly warm, which can take a long time because they are planted in the shade. Sometimes they may surprise you by emerging in summer. Another reason could be that they were planted upside down. The flat side should go down, knobby side up.