Rosemary is a hardy herb that can be cultivated in most places.
Rosemary prefers full sun, but can grow well in hot, semi-shaded areas. Growers should decide which variety is best suited to their needs.
Varieties include Arp, Flora Rosa, Irene, Tuscan Blue, McConnell’s Blue, Benenden Blue, Majorca Pink, Holly Hyde, Albiflorus, and Hill Hardy.
Cultivars differ in growth habits – they may be upright, lax and sprawling, or flat, almost hugging the ground. Most have blue flowers, but they also come in pink or white.
Leaves may be broad, thin or short and stubby, and the fragrance of the plant can vary from a rich, almost pine-like scent to virtually no aroma.
NO WET FEET
The South African Department of Agriculture, Forestry and Fisheries (DAFF) guidelines for herb production say that rosemary is usually grown under dry-land conditions.
It is important to irrigate at planting and until the plants are well established, but if cultivated under irrigation, don’t over-irrigate.
Once it has a strong root system, rosemary produces well in areas with average rainfall. It won’t do well in wetter areas, unless excess water is drained away.
Well-drained sandy to clay loam soil with a pH of 5,5 to 8,0 is ideal, but plants can tolerate a clay content of up to 30%. If the clay percentage is too high, dig in 1 mm to 2.5 mm diameter gravel into the soil before planting to aerate the roots. Good quality compost can also be added.
- Rosemary can be propagated from seed, cuttings, layering or by root division.
- The DAFF handbook recommends taking cuttings from the growing stem tip, as seeds germinate very slowly.
- Take cuttings of 10 cm to 15 cm long and strip the bottom two-thirds of leaves.
- Place the cutting in a growth medium. Rooting hormones will help roots to form within two to four weeks.
- Planting density and spacing depend on the farming method. If cutting is mechanised, seedbeds of 1.2 m wide and row spacing of 40 cm to 50 cm are most effective.
- Leave 25 cm to 50 cm between plants in the rows so that the soil covers over quickly.
- Apply a basal fertiliser containing nitrogen, phosphorus, potassium and sulphur annually, as determined by soil analysis.
- Additional applications of nitrogen can be given after harvesting to promote new shoot growth.
- Look out for pests and diseases such as spider mites, mealybugs, whiteflies and thrips.
- Insecticidal soap with horticultural oil can be used to keep the foliage free of pests.
- Rosemary becomes vulnerable to fungal diseases such as powdery mildew and rootrot if it receives too much water.
- Remove weeds and don’t allow them to seed.
- If the moisture content of the soil and the crop specification allow it, shade out weeds by increasing plant density and making rows closer.
DID YOU KNOW?
- Rosemary and sage grow very well together.
- The herb makes a good companion plant for cabbage, beans and carrots.
- When harvesting rosemary for drying, cut the crop frequently before flowering as the dried product only contains leaves.
- Rosemary aimed at the fresh market should be cut early to ensure shoots are fresh. Woody stems could lower the price.
- Harvest early in the morning and keep the product cool at 5˚C before packaging. At this temperature the product’s shelf life is two to three weeks.
- This article was written by Wilma den Hartigh and first appeared in Farming SA.