Soil and Climate Requirements of Lavender Plant
With its deep root structure, lavender has the ability to grow in low rainfall/arid regions where many essential oil plants cannot grow. However, extremely hot summers and mild winters are not suitable for commercial lavender production. Because while the extremely hot summers prevent growth and cause a decrease in yield and quality, the warm winter seasons cannot meet the cooling need of the plant in order to bloom abundantly in the summer period. In order to have a good flowering, it must be exposed to cold for a certain period of time in winter.
Although lavender can grow in soils with a very different structure, it shows good growth in dry and calcareous soils that are not rich in plant nutrients, rich in lime, sandy, without drainage problems and with a pH of 6.0-8.5. If it is cultivated in soils with high ground water, excessive moisture and rich in nutrients and organic matter, the essential oil rate decreases. Because in soils rich in nutrients and organic matter, when there is enough water, the plant continues its vegetative development and delays its flowering.
Due to its rich genetic variation, Lavandula angustifolia (English lavender) is distributed in regions ranging from cold to tropical climates and can be grown in regions with an altitude of up to 1700 m. Due to the formation of more and brightly colored flowers in plants depending on the increasing altitude, essential oil yield also increases in these regions. However, if it is cultivated in regions with very cold winters, there is always the possibility of being damaged by extreme winter cold. For this reason, it is beneficial to choose south-facing, closed to winds and slightly inclined areas when establishing plantations in cold regions. English lavender is not resistant to high humidity, regions with an annual precipitation of 300-1400 mm are more suitable for the culture of this genus.
Lavandula latifolia (German lavender) has a lower frost tolerance than English lavender and can be grown in areas with an altitude of 200-700 m.
Lavandula intermedia (Hybrid Lavender) is grown with greater success in regions with an altitude of 700-1000 m.
Lavender Production
Since the seeds of the lavender plant are small, the germination period of the seeds is long, the emergence of the germinated seeds and the first development period of the seedlings after emergence is very difficult, it is very hard to produce from seed and planting these seedlings in the field should be preferred rather than direct sowing method. However, growing seedlings from seed is a laborious and intensive care process, and it is very difficult to preserve the genotype of lavender due to foreign pollination.
The most widely used method in lavender production is the cutting(steeling) method. In this way, it is more possible to preserve the genotype of the lavender propagated. Each of the plants propagated by cuttings is a clone and the genotypes are the same as the parent plant used in propagation. For cuttings, steels taken in 10-15 cm length from healthy, productive and quality lavender plants are rooted in pillows consisting of 30% compost and 70% sand, which are kept warm and moist, after 3000 ppm indole-3 butyric acid (IBA) is applied (Baydar and Nimet, 2008). 2013). Hybrid lavender, which does not have the ability to form seeds as it is a hybrid species, can only be propagated in this way.
Two types of steel are used in reproduction by cuttings in lavender. These are soft and semi-hard steels at the beginning of lignification. Soft cuttings are preferred when a large number of rooted cuttings are needed and can be taken in two different times, in spring and autumn. If the cuttings are to be taken in the fall, the flower buds on the shoots should be removed in the spring or early summer and the formation of many soft shoots on the mother plant should be encouraged.
The length of the soft end shoots to be taken for rooting should be 6-8 cm. The leaves in the 3-4 cm part of the bottom of these 6-8 cm soft shoots are removed from the cuttings and planted for rooting by immersing them in the hormone solution. Rooting success is high in propagation using soft steels, and 90% of the cuttings planted in the pillows can be rooted. When a small number of steel is needed, propagation can be made from semi-hardened steels without any need for the use of heating and greenhouses (Beus, 2006). Rooting rate in the use of semi-hard cuttings varies between 50-80%. The timing of taking the steel is also very important in obtaining a successful result in steel production.
Planting Seedling
In order for the lavender seedlings to be removed and planted in a new field, the plant must be waited to go to sleep. In order for the lavender seedling to go to sleep, it is expected that the frost will fall depending on the climatic conditions. It occurs in the months of November-December. Planting of seedlings removed during this period can be done between November and March, depending on climate and soil conditions. After the seedlings are planted, life water should be given. Seedling planting can also be done in May, depending on climatic conditions. However, the yield in plantings made in autumn and winter months is higher than planting in May, as it is more suitable for the plant's need for cooling. It is very important to give life water to the plants after planting the seedlings.
It is extremely important that the field is cleared of weeds before the lavender seedlings are planted. Before planting, deep ploughing is made in the land, and seedlings are placed on the land that has been leveled with a disc harrow and rake.
140 cm row spacing and 35 cm row spacing are suitable for lavender cultivation, especially for Lavandula angustifolia species. These distances were calculated in this way due to the distance between the wheels of the tractor while the automation was harvesting. Accordingly, when planted, 2200 lavender seedlings can be planted per acre (1000m²). The fact that the fields where lavender will be planted are in the south and southwest directions, slopes and sun-exposed lands increase the yield. As Lavandula hibrida species. The fact that the soil is slightly alkaline and the pH value is between 6-8.5 makes an important contribution to the yield of lavender.
Fertilizing in Lavender Fields
In lavender cultivation, it is not desired the soil be too rich in terms of plant nutrients. Because the soil is rich in nutrients, besides negatively affecting the rate and quality of the essential oil produced, reduces the yield of flowers. Therefore, it is necessary to be careful when fertilizing. Especially Lavandula angustifolia prefers soils that are poorer in terms of plant nutrients compared to the other widely cultivated species.
The lavender plant needs most nitrogen and phosphorus. Nitrogen fertilizers provide vegetative growth (branches and leaves) of the plant. Nitrogen fertilization should be terminated after the lavender plantation has been fertilized for 3 years from the first year it was established. Nitrogen fertilizer, which will be applied every year in these first three years, should be divided into two and half should be given when the plants start to wake up in the spring and the other half should be given after the first harvest (Bienvenu, 1995, https://www.dalrrd.gov.za/, 2009, Beus, 2006). Phosphorus and potassium should be applied if the soil analysis reveals that there is a need. In addition, if the soil pH is too low, some lime can be applied to correct it (Bienvenu, 1995, https://www.dalrrd.gov.za/, Beus, 2006, Biesiada, 2008).
In order to improve the soil structure and obtain higher flower yield in lavender fields, farm manure is applied at a dose of 2-4 tons/da every 2-3 years and mixed with the soil (Aslancan and Sarıbaş, 2011). In recent years, worm fertilizer, which is an organic fertilizer type that is produced as a result of the digestion of fermented animal manure and food wastes by Red California worms, and contains trace elements, especially NPK (nitrogen-phosphorus-potassium) in a balanced way, is preferred by many lavender growers for fertilization needs.
Irrigation in Lavender Fields
The lavender plant is more resistant to drought compared to many plants used in the production of essential oil, and it is one of the aromatic plants that can be cultivated almost without the need for irrigation. The irrigation that the lavender plant needs most is the lifeblood application at the planting stage. In general, starting from the 2nd week after planting, this irrigation interval will be opened according to the need and continued until the plants take rootand will reduce the loss of seedlings (Gülşen, 2017). Although there is no need for irrigation in the following years, if the rainfall is very limited during the vegetation period and production is made on light (sandy) soils, irrigation is carried out especially at the beginning of flowering in order to increase the yield a little. However, excessive irrigation should be avoided as it encourages diseases. As an irrigation method, if possible, drip irrigation method should be preferred and the development of weeds should be controlled (https://www.dalrrd.gov.za/, 2009, Aslancan and Sarıbaş, 2011). If it is grown in areas close to the upper limits of elevations where lavender can be grown, excessive irrigation and nitrogen fertilization towards the end of summer should be avoided in order to protect the plants from winter cold. In such regions, if the weather is not excessively dry, cutting off the irrigation approximately one month before the first frost will reduce the risk of adversely affecting the plants from the winter cold (Gülşen, 2017).
Caring of a Lavender Field
One of the most important maintenance processes in lavender production is weed control. Especially in the years when the seedlings were first planted, the competition of the plantlets against weeds is very weak. For this reason, clean areas from the weeds should be selected as much as possible where the field will be established before planting. Then, weeds should be destroyed before planting with appropriate and consecutive tillage.
Weed control is very important in the lavender plantation in the first three years. In the following years, weeds are suppressed due to the allelopathic effect of the lavender plant, and after the first three years, there is no need for weed control (Aslancan and Sarıbaş, 2011). After hoeing 3 times in the first year, this process can be done with mechanical hoeing (10-15 cm deep) between the rows and hand hoeing between the rows in the second and third years. In some plantations, these numbers may increase up to 4-5 times between rows and 2-3 times above rows in the first year.
Mulching between rows in the production field (coating with polyethylene nylon or preferably organic material) is also a very effective method in controlling weeds. Mulching can be done either by hand immediately after planting, or by planting machines that can mulch during planting. Mulching can be preferred to increase product quality and preserve soil moisture for a long time (Bienvenu, 1995, https://www.dalrrd.gov.za/, 2009, Beus, 2006).
There are no important diseases and pests that will prevent the production of lavender. Only in some years, capped fungus and white root rot can be harmful to the root parts of the plant, and disease agents such as Septoria lavandulae and Ophiobulus brachyascus to the above-ground parts of the plant.
Development of the Lavender Field
Lavender growth is very slow in the first year, short stems occur. The main growth and yield starts from the second year. Lavender seedlings begin to flower from planting during their development. In the first two years, the flower stalks are short and the flower spikes are quite small. In the spring, pruning must be done before the plant starts to wake up. With pruning, the number of flowers increases. While some of the harvested plants are in new bud form, the flowering time of some plants passes and the oil yield decreases. For this reason, the main purpose in the first 3 years should be to accelerate the formation of side branches of the plant rather than flower and oil yield. For this reason, 2-3 harvests can be made per year.
Although lavender varies according to climate and soil conditions, altitude and directions of the land, it usually shows budding and then flowering in June-July. The period when more than half of the flowers dry upwards from the flower stalk is the harvest time of the plant.
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