3/26/2014
The Challenges of Growing Calla Lily
Rob O’Hara
The past few years, the popularity of Calla lilies has been growing pretty fast. We used to treat Calla lilies as an indoor potted crop, but over the last few years, this has really changed. Our Calla lily programs have been increasing every year in all pot sizes and have become a major item in garden centers for the spring season. With this rise in popularity, it’s become critical that we grow the best quality Calla to put on the market. Here are five tips that can help make for a successful Calla crop.
1 | Quality supply of tubers: It’s very difficult to grow great Callas without first having a great supply of tubers. Without this, it’s almost impossible. There are many suppliers of Dutch Callas, as well as U.S.-grown ones. Find one that can deliver the best bulbs at the best price. The inputs are high for this crop, so there can’t be any room for poor-quality tubers. When the bulbs arrive, they should be dry, hard and thick tubers. If they’re soft, squishy and thin, you may have a problem. A good supplier should also be able to help you with culture recommendations for their varieties. I’ve learned almost all of my Calla knowledge from good suppliers that know how to grow Callas and give great advice.
2 | Planting: Once you have your bulbs in house, it’s important to plant them properly. Not too deep, but also not shallow. I like to say we need to find the “sweet spot” in the pot. If planted too deep, they’ll be too wet. Too shallow and they’ll be too dry and not active. We like to apply a RootShield application right away and avoid the often recommended “cocktail” of fungicides. These cocktails often cause more harm than good and if your supplier is recommending so many fungicides, then maybe you should think about where the tubers are coming from. Once all planted up correctly, we then place them on carts in a warm house until sprouted—almost like a germination chamber technique. If you don’t want to place them on carts, then placing directly on a floor with heat and covering with cloth will also work.
3 | Moisture management: When the Callas are planted, we give them one watering (with the RootShield and fertilizer) after the transplant line, but after that, we keep them as dry as possible until well-rooted and sprouting. They don’t get their second watering until they’re moved from the rooting house to the greenhouse. Once in the greenhouse, it’s important to follow good wet-dry rotations, but avoid too dry once flowering. Keep an eye on the root systems for pythium as the crop is growing because too-wet conditions or high EC can cause this.
4 | Temperature: We start very warm to root, then once sprouted, we grow cooler to finish. We root them at 73 to 75F (23 to 24C) and then grow on to finish at 57 to 60F (14 to 16C). You can go warmer, but make sure the light levels are high enough. 60 to 64F (16 to 18C) works well under higher light levels and also speeds up crop time.
5 | PGRs: This is probably the single most difficult aspect of growing Callas. With the increased demand in the garden centers during spring, it’s more important to try and grow a shorter Calla to save on freight costs. We’ve struggled with this over the years and are still looking for the best practice for this. What we’ve been doing is working with Bonzi drenches at varying rates. Each variety from every supplier seems to react differently. From my experience, purple, pink, black and burgundy tones have always been less vigorous. Whites, yellows, reds, oranges and bi-colors seem to be more vigorous. Knowing how your varieties are going to respond to PGRs is very important, so keep good records and adjusts rates as you go along. One tool that we’ve found very helpful is the Dramm chemical dosing drenching machine. This has helped us to be very accurate with our drenching consistency and probably saved us on Bonzi usage over the years as well.
Calla lilies are very challenging, but when a crop turns out the way you want, then it’s a great feeling. Good luck with your Callas!
GT
Rob O’Hara is the head grower for Rainbow Greenhouses in Chilliwack, British Columbia, Canada.