Callas for Pot Culture

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Upon arrival

Tubers should always be stored dry at 50 to 65 F. The storage room should be well-ventilated. Never expose calla lilies to low temperatures, these tubers are very sensitive to frost and temperatures lower than 35F. Always check tubers regularly for soft rot (Erwinia), this is a fast-spreading disease that is extremely hard to control. No fungicides have been effective and therefore it is important to store tubers dry and well-ventilated, the only way to slow down the spreading of this disease in storage. Always be very careful in handling calla tubers, the littlest damage to the bulbs can spread the disease.


For container growing we recommend a soil mix that is fairly high in organic matter, It should definitely have good drainage. The pH level for the soil should be 6 to 6.5, it is also important that the soil is well sterilized.

Planting and Maintenance

We supply specially treated bulbs to increase shoot count. For maximum effect please plant bulbs as soon as possible after receipt. For container growing, plant tubers with growing tips up and barely covered with soil (1 inch deep max.). For cut flower culture outdoors (field-grown) plant tubers are 2.5 to 3 inches deep (same for flower beds in the greenhouse). The number of corms per pot depends on pot size. Are you growing in landscape-sized containers; we advise using 1 14/16 cm corm on a quart or 2 14/16 cm corms on a gallon pot. Are you growing in floral-sized pots?

Light Conditions

If Callas are greenhouse-grown, the plants should be placed in a high-light-intensity greenhouse. As for flower initiation, plants seem to produce more flowers in high-light intensity areas. Low light intensities can cause fading of the flower colour and increase plant height. In mid-summer, some shading may be required in greenhouse culture.


After planting, do not water the tubers until the next day, then water thoroughly. After the first watering, do not overwater, just keep the soil slightly moist. The plants are native to South Africa and do not need a large amount of water. Also, too much water can cause root problems and spread of the Erwinia soft rot. Do not water on top of the leaves but try to keep the foliage as dry as possible.


Plants should consistently be grown in a well-ventilated area.


The tubers do not require heavy fertilization, 1 to 2 times per month depending on growth. Use a slow-release fertilizer like 20-20-20. Do not apply fertilizer until plants start to show growth.

Days to flower

February plantings normally flower in 80 to 90 days. The early spring (March/May) plantings only take 65 to 70 days to flower. Plants start with a few flowers, and after about 2-3 weeks, there will be five weeks of peak flowering. After this stage, the plant will keep pushing up single flowers that can continue till the plant dies down. A single flower can last 2-4 weeks, depending on the variety and colour. Pink and cream flowers re-green first, and orange and black flowers last the longest. The flower re-greens quicker after pollination and loses its colour to avoid attracting insects, and with most varieties, the flower bends/starts hanging so that the seeds will stay dry. Plants will stretch in a greenhouse; move them outdoors if frost is gone to keep them compact.

Bonzai Treatment (only for pot culture)

  • Keep the soil a little dryer before you do the bonsai treatment
  • The first treatment needs to be done when shoots are around 1”, and the second treatment is when shoots are around 3” but not after the shoot is opening
  • Concentration 1 ml from the bottle (or four gr/l) per pot per gift (use lower concentrate for outdoor culture). Use 50-100 ML water per pot • Bonzai works best in cool weather
  • Keep pots a little bit dryer on the day of treatment to be sure the Bonzi will be well adapted by the plant

Flower harvest

If plants are grown for cut flowers only, the best time to harvest is shortly after watering. The flowers are easy to pull, no cuts have to be made this way, and there will be no extra risk of soft rot spreading. Always pull all flowers, this stimulates the plant to produce more new flowers instead of putting all energy in the existing flowers. Harvest as soon as the flower is fully opened but before pollen is shed, this way, flowers will last the longest. Flowers seem to respond positively to floral preservatives containing sugar and a fungicide. It helps to reduce stem splitting and rolling. Storage temperature should be 41 F.

Tuber harvest

Calla tubers can be harvested and planted again for production. If growers choose to save tubers after flower production, stop watering at least 10 days before digging and 6-8 weeks after flowering. Store tubers dry and cool at 55F. Bulbs do need a dormancy period of 12 weeks before re-planting. Check if tubers are dry, this way they are more mature and not as sensitive to damage. Be very careful with removing the foliage. The best way is to cut it off two inches above the tuber or soil level and dig it several days later. Store tubers in a dry and well-ventilated area. Try to dry tubers as quickly as possible. Do not divide any of the tubers before the roots and foliage are completely dry.

Our bulbs are treated to activate more growing buds. To have maximum profit from this treatment, bulbs need to be planted as soon as possible after arrival

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