Thyme (Thymus spp)

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. This is a new crop.

Background

Thyme is a small upright shrub common to anyone who has walked in the hills of Central Otago. It produces pink flowers in early summer with a very distinctive aroma. Thyme is originally a native of the western Mediterranean area and is thought to have been introduced to New Zealand by the early miners.

Thyme can be used in a number of different ways. As a dried herb it is used to flavour meats and many other dishes. Some special selections such as lemon thyme are often used to flavour fish. The essential oil is used as a fragrance in soaps and detergents. Thymol which is the major part of the essential oil has antibacterial and antifungal properties. Some research suggests that the Central Otago is not very high in this particular component. This fact needs clarification.

Winter Chilling and Frosts

With the abundance of plants in Central Otago it is clear that Thyme does not suffer from frosting and winter chilling is enough to set flowers.

Rainfall and Irrigation

Thyme does not grow in areas with heavy rainfall, however carefully timed application of irrigation water will significantly increase production over and above what would be expected without it. Use of T-tape or dripper irrigation is probably the best method of irrigating as it keeps the bush dry while making sure the roots have adequate moisture.

Wind

Because of the hardiness of the Thyme plant wind protection is not needed.

Soil

The key physical requirement of the soil for Thyme growing is a free draining root zone. This will ensure the roots are not always wet which can lead to fungal diseases.

Fertility

Thyme does not need high levels of soil fertility to grow well. Targeted applications based on soil and foliage tests are recommended. Aim for a soil pH of between 5.5 and 6.5.

Weed Control

Hand weeding and use of herbicides can be used to control weeds on a Thyme crop. However, planting cuttings through weedmat, may be the easiest way to grow the crop. This can be done in a similar manner to that used for Lavender.

Varieties

There are no named varieties of Thyme currently available. Taking cuttings in spring from a mother plant is the best way to ensure all the plants are the same in a block.

Pests and Diseases

Due to the harsh climate that Thyme likes few pests and diseases have been observed on the crop. The key seems to be having a free draining soil to prevent any fungal diseases on the roots. Plants are also susceptible to death after being cropped too hard. They do not have enough leaf area left to continue to photosynthesize and subsequently die.

Layout

Research suggests that beds should be 1.5m wide with plants 30cm apart within these rows. Rows should be far enough apart to allow whatever machinery is being used to get down them. Rows can be as long as is practical.

General Management

Plants are produced using semi-hardwood cuttings taken in either autumn or spring. Young plants should be placed in the field after the last spring frost. Irrigation and weed control are the two most important tasks as the crop develops.

Harvest

Harvesting tends to be done by machinery.

If harvesting for dried herb production three-four cuts should be possible per season, especially in climates such as Central Otago. Drying of the material should occur as soon as possible after this time at temperatures no greater than 40C. If the temperature gets higher, the volatile nature of the chemicals means that flavour can be lost.

If harvesting for oil the best time to harvest is at the peak of summer. Oil yields can be expected to be around 1.0% at this time, this drop to less than 0.1% in winter. The crop is left in the field to dry, then gathered up and steam distilled to extract the oil.

Equipment

After preparing the ground and planting most work on a Thyme block could be done mechanically. This means requirements for a tractor, spray unit, harvest machinery, bins etc.

Returns

It is very difficult to estimate returns for New Zealand grown Thyme. Finding niche markets will be the key to success.

Contacts

Crop and Food Research Ltd Broadsheet # 22: www.crop.cri.nz