Lilac (Syringa vulgaris)How well established is this crop?
This crop is relatively new. It has been grown commercially for 5-10 years. Commercial returns, current growers and some level of regional based research may be available to help those new to this industry.Background
The demand for lilacs appears to be increasing for both export and local market blooms. Flowers come in a range of colours from whites through to purple. They flower in the early part of the spring on the tips of last seasonís growth. Lilac is a slow grower and although flowers can be harvested from year 3 onwards, full production is not reached until years 6-10.Winter Chilling and Frosts
The exact amount of winter chilling required for lilacs to set flowers is not known. However as they are currently produced all over the Otago region it would appear that there is sufficient in this environment.
Hard winter frosts do sometimes have an affect on the tree by killing off the flowering buds on the end of last seasonís growth. At present there does not seem to be a practical way of dealing with this, especially in areas such as Central Otago.
Rain can lead to problems with fungal and bacterial diseases especially over the flowering season in spring. See section on Pests and Diseases.
If rainfall is not sufficient over the growing period supplementary water should be added, especially as the stems begin to lengthen. Drip or minisprinkler systems should be used to prevent wetting of the foliage and possible disease problems.
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 are recommending a multiplier of 10 for crops but with a valuable crop such as this, a more conservative 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 shelter design.
The key physical requirement of the soil for lilac growing is a relatively free draining root zone. They do like some humus content especially if initially used as mulch. If your soil is poorly drained, look at using field-tiles and/or Novaflo type products.
Lilacs prefer a slightly alkaline pH between 6.5 and 7.5. The use of Lime is the easiest way to move the pH of the soil upwards. More specific information is hard to give but a simple soil test followed by an expert analysis of the results will allow the owner to correct any potential imbalances.
Weed control in lilac blocks is important for two reasons. Firstly it allows easier access to the plants for activities such as spraying and harvesting. Secondly, by reducing the amount of vegetation around the lilac plants you reduce the potential for weeds to host pests and diseases.
Weed control can be achieved using three means. Pre-emergent herbicides can be used successfully in some cases. Post emergent herbicides are also common provided care is taken around the crop plants. Spray guards and even AI (air induction) nozzles help prevent this. Another technique is to grow the plants in weed mat.
The majority of the lilacs you buy today are grafted onto Privet rootstock. This commonly suckers and these will have to be removed by hand before any spraying can be done.
Because of the uniqueness of lilacs in the market there are no preferred named varieties, however this is likely to change in the future. Flower form seems to be the main factor with buyers. Single flowers or those that appear on the end of the stem in threes, fours or fives are ideal. Flowers occurring in twos are not as popular.
Most Lilac plants you buy today have been grafted onto Privet rootstocks. The reasons for this are still unclear as this stock tends to die out after 5-10 years. To get around this problem it is advisable to plant the graft union beneath the soil to encourage the scion wood to produce its own roots.
To grow Lilacs flowers successfully for export, agrichemicals must be used. The plants suffer from stonefruit blast (Pseudomonas syringae) a bacterial disease, and powdery mildew a fungal disease. Only a few insects are a problem on the crop including leafrollers, thrips and mites. There is a zero tolerance to these insects when exporting flowers, meaning some form of post harvest treatment is needed.
Lilacs can grow to fill in a space at least 3m all around and 5m tall. They are best planted in single rows to allow access in and around the plant as it grows.General Management
Observation over the past few years has shown that lilac bushes have a very short period of vegetative growth. This lasts from flowering through until just after Christmas. After this time the stems lengthen very little. Flowers are produced on this wood the following spring. Pruning should be done immediately following flowering as this gives the remaining stems the best chance to reach their maximum length.
After Christmas, the bushes seem to sit before losing their leaves for winter. This is a good time to get on with cutting back suckers that will have grown during the season. Herbicides can be carefully used around the plants to control weeds once the bark on the stem has hardened. Spray guards around the stems are useful before this time as they also prevent rabbits eating into the bark.
Harvesting lilacs is a relatively straightforward process as the stems are simply cut with a knife or secateurs. The stems are cut when approximately 50% of the flowers are open if exporting or when approximately 75% of the flowers are open if they are being sold on the local market.Equipment
Lilac growing requires limited amounts of equipment. Once planted, blocks can be managed with a back-pack spray unit and general gardening equipment. Larger blocks may require a small tractor unit for spraying and grass mowing etc. If exporting, access to post-harvest fumigation equipment will be needed.
A number of post harvest solutions have been suggested to enhance the shelf life of lilac flowers. Chrysal#2 seems to be the most popular at the moment. Talk to a exporter for more up-to-date information.
Lilacs have been sold on both the domestic and export market for some time. Domestic returns are around 60c stem, with export returns anywhere from $1.50 - $3.00. (2003-04 season prices). Costs of production are unknown at this stage.Contacts
There is no central organisation for lilac growers. You are best to make enquiries through your local flower growers group and talk to a flower exporter.