Lavender belongs to thermophile plants and requires high temperatures and plenty of sun and sunlight during vegetation in order to accumulate its essential oil. Warm, wind-protected soil is favourable  in lavender growth. Cold soil and frost can harm the crop, although the plant can take temperatures of  -20 ºC during the resting phase. In cases when vegetation starts early, hybrid lavender may be harmed due to late spring frosts. If the weather is rainy and cold during the blooming phase, the content of essential oil is reduced even in  50%, as well as the content of ether in it (up to 30%) . Lavender can easily survive periods of droughts, except for the initial period of growth.

Common lavender does not require any specific soil, it is grown equally well in shallow, poor soil and in limestone areas. Hybrid lavender requires more care and yields highest in deep, fertile soil with the proper water and air flow, but it can be grown in the type of soil favourable in common lavender growth. Neither common nor hybrid lavender can grow in cold, impermeable pseudoclay and sandy soils.

One year prior to starting a lavender plantation, deepest possible autumn plough should be done. In case there is a possibility of forming an impermeable layer, the soil selected for cultivation must be ploughed. The last previous forecrop needs to be a legume which needs to be harvested by September. Immediately following the forecrop harvest, the soil needs to be ploughed at the depth of 18-20 cm, fertilized, and the surface layer of soil needs to be made loose to 15 cm depth and settled by the time sowing starts.

Lavender remains in the same place for the period of 15 to 20 years. The forecrop needs to leave the soil weedless. The young plant is extremely sensitive to dissolvable herbicides, and can be sown in the same soil after maize only after the period of two to three years has passed.

Propagation has been used in reproduction of both lavender types. Cuttings are rooted in non-heated beds and covered with a foliage. The best clones are those cut from 3-4 year old bushes, cut in August or April. The clones are put into sand, 4-5 cm deep, 6-10 cm between the beds and 2-3 between the clones in one bed. These should be watered abundantly. The rooted clones are replanted into open beds at the end of May. One square metre may provide with 600-800 clones.

Hybrid lavender clones can be grown in open areas, in loose soil rich in humus and with plenty of water. The  12-20 cm sprouts are cut in October or in March and lain into the prepared soil, to 18-20 cm deep beds that have previously been watered.  The distance between the rows should be 35-40 cm, while the distance between the two sprouts in one row should be 3-5 cm. As the beds are coated with earth, the height of the clone remaining above the ground  is only 7cm. These should be watered 3-5 times during the following few days. When the sprouts reach 15-20 cm in height, they should be cut at the height of 8-10 cm in order to enhance the growth of lateral sprouts. 700 000 to 900 000 clones may be cultivated on one acre.

Common lavender is mostly reproduced by seedlings obtained from the seeds, but it can be reproduced vegetatively, by plant green seedlings and clones. Hybrid lavender is reproduced only vegetatively, as its seed is sterile.

Prior to sowing seeds, hotbeds should be prepared in shaded places and the soil disinfected by methyl bromide. Sowing is done before winter, in November, or during early spring season, in March. Spring sowing requires the seed to go through the process of stratification, 36 hours at 16 ºC. Sowing can be done manually or mechanically at the distance of 20-40 cm between the beds and at 0,5-1,5 cm of depth at the beginning of May. When the plants form 4-5 leaves, they are pricked into open hotbeds at the distance of 35x5cm. With regular water supply, the plants remain there until autumn. 18-20 cm high plants are pruned to 8-10 cm of height in order to branch. 600 000 to 800 000 seedlings may be grown from 7-9 kg of seed in one acre.

It is a common and a cheap way of hybrid lavender reproduction. Propagated lavender is prepared in spring, when there is no frost. 3-4 year-old plants are coated by loose ground to the height of 30 cm. Coated plants need to be provided with enough moisture. In autumn, following the rainy season, the ground is uncoated, well rooted branches are cut by scissors and planted. 100 to 150 propagated lavender plants can be obtained from a middle-sized  bush. All seedlings are planted in autumn, during October. Spring planting is not recommended, the last period for successful planting being March. Only properly developed seedlings are planted, but their root should be cut to 15 cm in length. Lavender is planted manually or mechanically. Common lavender is planted into 150 cm distanced beds and with 40 cm distance between the plants in one bed, with the capacity of 16700 seedlings per acre. Hybrid lavender is planted into 180 to 200 cm distanced beds with 50-60 cm distance between the plants in one bed, and the capacity of 9200-1000 seedlings per acre.

Essential cultivation of crops requires pruning at the end of May, when plants are cut to 8-10 height in order to form a thick shrub. The plant is once again pruned in its second year to the height of 15-18 cm. Following the second pruning, there is no need to form the crown further. At the end of the plant’s first year,  stronger seedlings are added to the already planted area, as only fairly even crop can be machine cut in a satisfying way. It is important to cultivate the soil regularly, and to hoe the crop in a row. Weed should be suppressed before vegetation period begins. Common lavender starts growing old after 6-8 years, shrubs become thinner, flower buds lessen in number, and stalks become shorter.

Sources:

BIOPA; Lekovito bilje

Dr. I. Šilješ, ing. Đ. Grozdanić, mr. I. Grgesina; Poznavanje, gajenje i prerada ljekovitog bilja; Osijek, 1992.