Allium (Allium giganteum)

How well established is this crop?

Initial trial plantings of these crops may have been done. There is little information on plant suitability to the region and no current information on markets, commercial returns or current research.

Background

Alliums are a perennial flower and are a member of the onion family. They grow from a bulb and produce a flowering head on the end of a green fleshy stem. The flowers come in a range of sizes and shapes. Nearly all are blue, lilac or purple. Although they have been grown for a number of years in the home garden, new cut flower selections have made alliums a viable commercial crop. These new selections have lessened the onion smell that often went with these flowers.

Winter Chilling and Frosts

Alliums require a period of winter chilling before they will send up flowering shoots. No work has been done on the exact amount, but it appears all areas of Otago have suitable chilling to allow flowering of this crop.

In Holland growers simulate this natural chilling by placing flowers in coolstores. This allows them to manipulate the flowering time.

Rainfall and Irrigation

Rain will not affect an alliums crop at any stage of its growth, except near flowering when the weight of water in the head may cause the stem to tip over.

If rainfall is not sufficient over the growing period supplementary water should be added, especially as the stems begin to lengthen. T-tape or drip systems should be used to prevent wetting of the foliage and possible disease problems. Growing in a well drained soil will ensure that bulbs are not wet for long periods which can also causing rotting.

Wind

Like most high value flower crops, shelter from the wind is essential. This can take the form of natural tree shelter or artificial shelter using wind cloth. A good rule of thumb when designing shelter is to multiply the final height of the shelter by 5. Use that measurement as the distance you position your shelters apart. For example, when using 2m high windbreak cloth, you will need shelters every 10m. Some consultants in the Otago region are recommending a factor of 10 as a multiplier, but for flower crops a more cautious approach is advised.

If using natural tree shelter, make sure the shelters running east-west are deciduous. This will allow sunlight into the blocks in the winter. Position all shelters at right angles to the prevailing winds. Talk to your local nursery when deciding on the right tree type for your property. They may also be able to help with design.

Soil

Alliums require free draining soil around the root zone. As they are a bulb they are prone to rots if in constant contact with water.

Fertility

Alliums require moderate soil fertility to grow well. Specific information is hard to give but a simple soil test followed by an expert analysis of the results will allow the owner to easily fix any potential nutrient imbalances.

Weed Control

Allium beds must be free of weeds as the plants come away in early spring. Maintaining this control as the plants continue to grow and flower around Christmas will mean less weed seeds the following season.

Varieties

There are no preferred varieties of alliums in the marketplace at the moment because they are such a new crop. Greenharvest Pacific, an Auckland based plant importer, has the widest selection. See the contacts section at the end of this datasheet.

Pests and Diseases

Alliums suffer from a range of pests and diseases. Several viruses are known to infect stock overseas so make sure anything you buy is guaranteed virus free. Fungal diseases known to affect the crop include Rhizoctonia, Pythium and Fusarium. Regular use of fungicides, dips, drenches, and sprays will be required to grow this crop successfully. Insects including aphids and thrips have been observed on allium plants growing in Southland.

Layout

Alliums are planted in beds approximately 1m wide to allow access from either side for picking. Anywhere from 9-20 plants per square metre is the most common method. The rows can be as long as is practical, and the distance between them is sufficient to allow for foot or tractor access, depending on machinery.

General Management

Growing alliums is relatively straightforward. As long as the beds are weed free at the start of the season, they essentially look after themselves. Some form of crop support will be needed if they are growing on a windy site. Irrigation and then an insecticide before harvest is all that is required.

Harvest

Harvesting alliums is relatively straightforward as the stems are simply cut with a knife or secateurs. The difficulty is deciding when the stem is ready for cutting. In general the flowers on a stem should be 90% open before harvest.

After harvest the stems should be placed immediately in a postharvest solution and transported back to the packhouse. They should stay in this solution in the chiller until they are packed for export.

Equipment

Most alliums blocks will be small and can be managed with a back-pack spray unit and general gardening equipment.

Returns

As this is such a new crop returns are unknown.

Contacts

If you are thinking of growing alliums, talk to Ted Downing from Greenharvest Pacific in Auckland on 0800 447 864 or contact your local Flower Growers Groups for the names of other growers.