Calla Lilies Above Ground and Below
Dewhurst farm sells high-quality tubers and cut flowers to the world
I've written about Bruce and Brian Dewhurst and their very impressive NFT lettuce operation (Growing Edge Vol. 18 No.2; Vol. 18 No. 3). In this issue I will talk about another side of their business- calla lily (Zantedeschia) flower and bulb production.
Unlike lettuce operation, the Dewhurst calla lily operation is a seasonal thing. It's based primarily on the production of high-quality bulbs, or, more properly, tubers. Tubers meeting rigorous grading standards are then exported, many to the United States. As a by-product of this operation, a considerable harvest of cut flowers adds to the success of their operation.
To be competitive in the world market, it's essential that new and exciting colors and forms are continually developed. A Tauranga-based company Bloomz creates new varieties and colors of flowers. Parent stock is sent to India, where tissue-cultured stock is produced. This stock is then sent to many growers, including the Dewhursts, who plant them out.
Tuber, Cut Flower Production
In the first year the plants do not produce flowers. The main point of this exercise is to grow the resultant tuber to a marketable export bulb. With good management a large percentage of the bulbs will attain a marketable size. All those not growing large enough in year one, or any bulb that shows a physical imperfection, will be stored and replanted next year, when they, or their progeny, by virtue of bulb multiplication, will most certainly be large enough, and blemish-free, for export sale.
The site has two growing areas. The first being the relatively high-density plantings of tissue cultures, 190 into each 900-by-500-mm (± 36-by-20-inch) growing bins, with a total of 170,000 cultures being planted.
The second area sees all those second-year bulbs that either were too small or were marked in any way being planted out at a lower population density. These will result in producing a good crop of flowers and ± 120% of export-quality bulbs.
Tubers 1 cm to 3 cm in diameter (0.39 inch to 1.2 inch) are planted into wooden bins. Good drainage is imperative, so these bins have large drainage slots in the base.
The preparation, filling and planting is a highly organized operation, and on a good day 220 bins, holding over 20,000 tubers, will be completed.
Once picked, the blooms are assembled and sorted into their unique bloom shape. The flowers are freighted back to Tauranga, where the co-operative flower-processing plant will carry out postharvest treatment in preparing the blooms for export.
Quality Control
Once the flowering season comes to an end, the plants will be allowed to die down in the normal way. Ultimately, the bulbs will be recovered, graded and sorted between export quality and those which will be replanted again next season. The sorted bulbs need carefully climate-controlled storage to ensure that they will be in top condition when planted again next season.
One of the risks of growing these crops is the constant potential for disease to set into the bulbs, the worst being pathogens that kill the tuber cells and allow rot to set in. This is the reason why all the bulbs are planted into separate bins, so that at the first sign of a problem an individual bin can be isolated from the main crop and any outbreak nipped in the bud. Likewise, the efforts put into maintaining optimum storage conditions is great insurance for protecting next year's crop.
