Geraniums (Pelargonium x hortorum) make popular bedding plants in the garden, but they’re also commonly grown indoors or outside in hanging baskets. Growing geranium plants is easy as long as you can give them what they need.
Essential oil of scented Geranium is widely used in high grade perfumery and cosmetic industries. It is also employed as a flavouring agent in many major food categories, alcoholic and soft drinks. Traditionally Geranium is used to staunch bleeding, healing of wounds, ulcers and skin disorders and also in the treatment of diarrohea, dysentry and colic. The oil has antibacterial and insecticidal properties and is profusely used in Aromatherapy.
The oil is priced at Rs. 3,200 to 3,500 per kg. Farmers can expect to earn an income of about Rs.1,00,000 from one hectare of crop with a net profit of about Rs. 60,000.
Scientific name: Pelargonium cv. rosé
Common names: Rose geranium
Family: Geraniaceae
Climatic requirement
Rose geranium prefers warm temperate to subtropical climates with a long growing
season without extreme weather conditions. It grows well at a temperature
range of 10 to 33 °C, and it needs enough sunshine for the development of oil in
the plant. The plant is sensitive to cold weather and cannot withstand frost.
The favourable rainfall for dryland growing of rose geranium should range from
700 to 1 500 mm per year
Soil requirements
Rose geranium can be grown on a wide variety of soils. It prefers well-drained
sandy to loam soils with a pH range of 5,8 to 8,5 and sunny, hot, frost-free conditions.
Ideal soil types should be rich in organic matter and have a clay content.
Seed sowing
Plant spacing should be adapted for mechanisation. Generally, a row spacing
of 40 cm, with a row width of 50 cm that will give a total of 50 000 plants per ha
when growing in a high-rainfall area or under irrigation, is recommended. With
such spacing, 60 000 to 80 000 plants per ha can be achieved. In areas with
lower rainfall, density can be 20 000 to 30 000 plants per ha.
Sowing time
seed being produced, and propagation is done by cuttings from mother-plant
material or by means of tissue culture. Planting of cuttings can be done as soon as the active growing season commences, i.e. in spring, and during most times of the year when soil moisture is sufficient. Avoid planting during very hot times of the year and close to and during winter time when plants are usually dormant.
Irrigation
Irrigation should be done on alternate days during the first week and later at an interval of 5-7 days.Overhead, flood and drip irrigation can be used. Overhead irrigation should be
used with care as it may cause loss of oil at certain stages before harvesting.
Nutrient management
The crop responds well to macro and micronutrients. About 100-120 kg of urea is applied as side dressing in four split doses during the crop’s growth. Calcium and potassium are important for successful growth. Phosphorus uptake is enhanced by mycorrhizal fungi association present in the soil. There is a close correlation between phosphorus and essential oil production. High nitrogen levels can increase herbage yield, however, it could
result in lower oil yield per mass.
Inter crop
Blackgram, garlic, onion and peas can be planted as intercrops.
Weeding
Weeding must be done 30 days after planting.Hand-weeding and hoeing are very important as weeds affect the yield and quality of oil. Generally, 2 to 3 weed sessions are necessary during the year. Inter-row cultivation can be done by a tractor-drawn cultivator or hand hoe. Care should be taken not to damage roots. Exclusion of sunlight is one of the best weeding practices. Therefore, rose geranium should be planted so that it forms a canopy quickly. Cover cropping practices with plants that inhibit weed growth are advised. Mulching with compost or grass will inhibit weed growth. Pre-emergence application of pendimethalin (0,75 to 1,00 kg AI per ha) or oxyfluorfen (0,25 kg AI per ha).
Pest control
Rose geranium is attacked by many different species of pests belonging mainly
to the Hemiptera, Coleoptera and Lepidoptera families. Among the most important
pests are the white grubs, cutworms, cockchafers, whiteflies, aphids, mites,
termites and white peach scale. Chemical control seems possible as well as biological control with a nematophagous fungus and/or companion cropping with nematicidal plants
(periwinkle, marigold).
Cutworms can be troublesome when young plants are transplanted into the
land. They can be eradicated by using biological means and poisoned bait.
Thrips are often the most serious insect pest in greenhouses. They are very difficult
to control once a population becomes well established. They feed on leaves
Whiteflies are a very frequent pest in greenhouse production. During development, whiteflies are usually found on the underside of leaves. The adult and immature stages of whiteflies use their piercing/sucking mouthparts to extract fluid from the plant tissue. Whiteflies also produce sticky honeydew that can be a growth medium for black sooty moulds.
Spider mites are very small arthropods that develop mostly on the undersides of leaves. Spider mites cause damage/injury to plants while feeding. Using their piercing/sucking mouthparts, they extract plant sap. Feeding injury often gives the upper leaf surface a characteristic mottled or speckled appearance. Large numbers of spider mites produce a web that can completely cover the leaves and flowers.
Aphids have small, soft bodies with piercing/sucking mouthparts that they insert into the phloem tissue of plants and remove sap. Aphids cause injury by feeding, the transmission of viruses, and further damage by spreading sticky honeydew over the surface of the leaves and flowers. Encourage beneficial predators such as ladybirds and syrphid flies.
Mites can cause a scorched appearance on young leaves, which then curl up and drop off. Control with sprays of insecticidal soap, horticultural oils and currently recommended insecticides.
Subterranean termites may attack rose geranium as they tunnel through the stems and cause the plants to wilt, turn yellow and die.
Snails and slugs may be a problem. They can be trapped by placing out saucers
of stale beer or using dichotomous earth.
Disease control
leafspot and blossom blight
It is caused by the fungus Botrytis cinerea that penetrates the plant tissue through the wounds and reproduces itself in humid atmospheres, causing darkgrey stains. It is very frequent during cool and moist weather. Water-soaked lesions occur first, which later dry out and are covered with a greyish-brown mass of fungal growth. When the petals are infected they become discolored, wilt and fall off.
Control: Ensure good air circulation and full sunlight, and keep the plants on the dry side. Use fungicidal sprays if the disease is severe.
Rust
It produces stains of a yellowish-brown colour in the inferior part of the leaves, causing die-off at a later stage. It is produced in plants subjected to high temperatures and humidity. Powdery, golden-brown pustules appear on the leaves, petioles and stems. The leaves turn yellow and drop prematurely.
Control: Avoid purchasing infected plants. Spray with fungicides if the disease is found in the land.
Bacterial blight (Xanthomonas campestris pv. pelargonii)
Takes place by the action of Xanthomonas campestris pv. pelargonii that produces stains in the leaves and dark necrosis in the stems. It results from a too humid and hot atmosphere, and as a consequence of wetting the leaves. It can sometimes be treated with fungicides. The disease is favoured by warm, humid weather, crowding of plants and planting infected stock. Sometimes rose geranium begin to rot in the stem, just in the area that it is in contact with the soil and the disease advances to the entire stem until reaching the leaves.
Control: Copper fungicides are effective. Alternaria leafspot (Alternaria tenuis) It is a fungal leafspot resembling bacterial leafspot.
Black leg (Fusarium sp.) and black stem rot (Pythium splendens)
These rots occur on cuttings and occasionally on fully grown plants and are most frequent in hot, humid conditions. The rots start at the base of the cutting and progress upward, blackening the stem and defoliating the plant.
Control: Take cuttings from healthy plants only which have been kept dry. Sanitise cuttings before rooting and root the cuttings in a sterilised rooting medium. Sanitation to sterilise cutting tools is by using a bleach solution. Fungicidal sprays are useful.
Harvesting
Geranium crop is harvested after 4-5 months of transplanting.The first harvest can be obtained after 3 to 6 months, depending on cutting size and locality in South Africa as well as nutrition and moisture. Harvesting is done 3 to 4 times per year, beginning 3 to 6 months after planting. When the leaves start turning light green they exhibit a change from lemon like odour to that of rose. The change in colour of leaves and odour are the main criteria for harvesting. Green leafy shoots are harvested with a sharp sickle. The crop, after harvesting, is maintained by weeding, fertilizer application and irrigation. It puts forth fresh shoots, grows fast and reaches a harvesting stage in about four months. Though it can be maintained as a perennial crop, it is advisable to replant after two years as wilt disease affects the crop.
To ensure good oil yield, it is better to wait a few days after rain and having at least 3 days of hot sunshine before harvesting. It has been shown in trials that oil yields increase with stress factors such as moisture and heat.
