Everything you need to know about growing almonds! Learn about: 1. Botany of Almond 2. Climate and Soil for Almond 3. Orchard Cultural Practices 4. Propagation and Rootstocks 5. Planting Operation 6. Flowering and Fruiting 7. Training and Pruning 8. Harvesting and Handling.
Botany of Almond:
Almond (Prunus amygdalus) belongs to the family Rosaceae, Genus Prunus and Subgenus Amygdalus. Morphologically and taxonomically, almond is very closely related to peach. The tree characters of peach and almond are very similar. The chief differences in the two are found in matured fruits. The fruit of peach is a delectable esculent, that of almond inedible. The flesh of peach is fleshy, juicy and soft, that of almond thin, tough and leathery.
The pit of peach must be removed, while that of almond drops off naturally from hard flesh which splits at maturity. The pit of peach is deeply sculptured and of bone-like consistency, that of almond is nearly smooth and in some varieties thin and soft in texture.
The buds of almonds are solitary and pointed those of peach in triplets with the central bud being pointed and vegetative and the side buds rounded and floral. Both almond and peach have low chilling requirement. Almond, in general, needs somewhat lesser chilling than peach as it sprouts earlier.
Botanically almond fruit is not a nut but a drupe. Exocarp is a thick, leathery, grey green in colour is called the hull. Inside the hull, hard woody shell is the endocarp. Inside the shell is the edible seed which is called a nut. Thus edible portion is cotyledons.
Climate and Soil Required for Growing Almonds:
Almonds can be grown successfully both in temperate and subtropical areas with low rainfall. Precipitation at the time of flowering and fruit maturity is injurious. The areas where almonds are being grown successfully in the world are located between 30° to 40° N or S. Elevation of prominent almond-growing areas ranges from above 700 to 2500 metres above sea level.
The altitude of almond growing areas in Kashmir ranges between 1500-1800 metres above sea level. Almonds can be grown successfully on lower elevations. The most, tender stage is blossoming and development of young fruit is shortly after dropping of the husk. The blossoms can often withstand temperature from – 2.0 to – 3.3°C for a short time. If low temperature continues for many hours they get damaged. As almond is known to have low chilling requirements, warmer aspects are preferable for its cultivation.
Thus, it has more chances of success on the western and southern aspects of the hills as compared to the northern sides. Srinagar which is located in the midst of almond belt has an altitude of 1650 MSL. The place gets an annual rainfall of nearly 400 mm which is well distributed throughout the year. About one-third of the rains are received in spring months.
Almond requires a fairly large number of heat units for crop maturity and may not do well at places where summers are cool and foggy. At a place known as Dalwal in Jehlum district of West Pakistan, almonds are grown successfully under sub-montane and subtropical conditions.
The chilling requirements of almonds for proper growth and fruiting are rather low i.e. an exposure to low temperature of 250-500 hours below 7.2°C during winter is only needed. This requirement of about 200-350 hours of chilling temperature is usually available in the plains of Punjab.
Almonds are not very fastidious in their soil requirements. However, good drainage is essential. In poorly drained soils, even well grown almond trees collapse suddenly whenever the soil remains saturated for 3 to 4 days.
Light loam soils are considered suitable for almond while heavy soils are not desirable. The ideal soil is the deep alluvial type. Shallow soils overlying calcareous subsoil tend to dry out rapidly during summer unless frequently irrigated.
Orchard Cultural Practices for Growing Almond:
i. Irrigation:
Irrigation is the most important practice to improve the growth and yield of almond. In Kashmir, almond has proved as an exceptionally hardy tree, which can withstand drought as well as negligence remarkably. The almond orchards here are growing under rainfed conditions and are seldom irrigated. The trees should be given 3-4 irrigations during dry spell for achieving better yield and plump kernels.
Frequent dry summer irrigation is good for proper development of nuts and prevention of fruit drop besides laying foundation for the next year’s crop. For successful growing and cropping of almond tree 65 cm or more annual rainfall is needed.
In case of established plants of almond, a 10 day interval of irrigation in summer and about 20-25 days during winter is sufficient. In the event of rainfall, irrigation may be suitably delayed and adjusted.
ii. Manuring and Fertilization:
Fertilization of the almond trees in Kashmir is rarely practised but some almond growers do apply nitrogenous fertilizers. Some apply di-ammonium phosphate which also provides phosphorus.
At Hariparbat, each tree is given 1 kg urea + 500 g potassic fertilizer.
The addition of nitrogenous fertilization to almond is important- Two to three kg ammonium sulphate and one kg superphosphate per tree annually are considered adequate doses.
It is reported that 200 kg P and K per hectare should be applied before planting. Subsequently 100-120 kg N, 50-60 kg each of P and K should be applied annually to maintain the fertility of the bearing orchards.
Nitrogen should be given in three split doses i.e. in February, March and April. The phosphorus and potash should be given in single dressing during December or January. In Kashmir for 10 years and above old almond trees, 450 g N, 65 g P2O5 and 600 g K2O is recommended.
Nitrogen may be split in 2-3 doses. First dose (half the quantity) should be applied along with phosphorus and potassium a fortnight before expected bloom, second dose (25% of total quantity) may be applied about three weeks after fruit set and third dose (25% of total quantity) should be applied in June-July. It is also reported that full grown almond tree need 50 kg FYM, 500 gN, 250 g P2O5 and 700 g K2O for better tree growth and yield of kernels.
Propagation and Rootstocks of Almond:
The old plantations in Kashmir valley have all been raised from seeds. Vegetative propagation by T-budding and Tongue or cleft grafting is most successful.
Rootstocks:
The most commonly used rootstocks for almond in Kashmir Valley are the seedlings raised from sweet or bitter almond. Wild peach is also used in certain areas of valley. Sweet almond seedlings are being favoured more because of the reason that if the budded sprout fails, at least the tree will yield sweet almonds.
In Australia, the Challeston variety has been a good source of seedling rootstocks. The variety California Paper Shell has proved as a good rootstock for poorly drained soils but the performance of almonds budded on plums has been highly variable.
Almond, peach and Marianna plum are the common rootstocks for almonds. The almond seedlings are the most satisfactory and widely used. In Himachal Pradesh, Behmi Prunus mira is also widely used as a rootstock for almonds. In a rootstock trial conducted at Solan, wild peach was observed a better rootstock than either bitter almond or Behmi. The wild peach rootstock was most vigorous and produced the maximum yield of green almonds, whereas the Behmi rootstock was the least vigorous and produced minimum fruit yield.
At Dunda, Uttarkashi, bitter almond was considered as the best rootstock on the basis of different growth parameters, though the plants on local peach were more vigorous and those of Harsil peach were dwarf. Under the subtropical conditions of Punjab, the almond cultivars on Kabul Green Gage plum rootstock produced more flowers per spur and took significantly less time to mature the crop than those on sloh rootstock. However, fruit set was significantly higher in trees grafted on sthan those of Kabul Green Gage rootstock.
Raising of Seedlings:
The almond nuts are harvested from July to September and are stored in a cool and dry place till December. Stratification of nut is needed to break the rest period. The nuts are stratified in sand in boxes in the end of December. It consists in putting a layer of sand 3 cm thick at the bottom of the box and spreading almond nuts over it in 3 cm thick layer. They are covered over with a second sand layer of the same thickness and again a layer of nuts is put over it.
In this way, 4-5 layers of seeds and sand are placed. By the middle of February, the hard shell of the seeds breaks open by absorbing moisture and the Kernels which begin to show signs of germination are exposed partly or wholly. When the shells have split partly, the nuts are taken out from the stratification box and sown in beds.
Seeds are sown 3-4 cm deep on well cultivated and manured beds in lines 30 cm apart. The seeds within a line are sown at a distance of 10 cm. A distance of 60 cm is left after every two rows which will facilitate the budding process and cultural operation in the nursery beds. Germination starts in 2 to 3 weeks.
For direct stratification, seeds are sown in lines in the nursery beds by the end of December. The seed received the required chilling in the field and starts germination as soon as the soil temperature is favourable. These nursery beds are irrigated from time to time to keep the soil in moist conditions. A fairly good germination is obtained by this method also. The seedlings make vigorous growth and become fit for transplanting in their permanent places in the orchard after one year.
Vegetative Propagation:
When the seedlings are of pencil thickness and have attained a height of 30 cm they are T-budded in June to August. The seedlings which are do not make sufficient growth so as to become fit for T-buddings, are Tongue or cleft grafted in December- January. Tongue grafting is employed when stock and scion are of equal thickness.
Recently mound layering, stooling etc. is also being tried for multiplication of almond plants.
Planting Operation for Growing Almonds:
The land should be thorough prepared for almond planting. The pit should be dug 1 x 1 x 1 m size atleast fifteen days before actual planting. Depending upon the nature and fertility of the soil, almonds can be planted 6-7 m apart. The square system is easiest to plant and maintain. With the suggested planting distance 202-275 plants will be accommodated in one hectare.
In Kashmir, budded plants are planted by square or hexagonal system at a distance of 5.4m-7.5 m depending upon the soil fertility, vigour of the tree and availability of irrigation. The planting should be made in autumn. Under Punjab conditions, the best time for plantation is the end of January.
Almond sprouts very early and if plantation is delayed beyond January the rate of mortality may increase. Till sprouting starts, irrigation may be given at 10 day intervals, thereafter light irrigations should be given at weekly intervals.
The varieties of the almond are mostly self-unfruitful which is due to self-incompatibility. It is, therefore, necessary that more than one variety of almonds should be planted in an orchard. Ordinarily one variety will pollinate any other variety, provided their flowering periods overlap and when the pollens of the one variety are produced while the pistils of the other are receptive. The varieties with long flowering periods are considered to be good pollenizers.
The best method to plant the different varieties together is to put 3 rows of the main variety and one row of the pollenizer variety. It is also useful to have 3-4 colonies of bees per hectare of orchard.
Flowering and Fruiting in Almond Trees:
Almond is one of the first trees to blossom in spring and for this reason, it is very susceptible to spring frosts which make its cropping very uncertain from year to year. The bud differentiation in almond starts in August:-September and continues upto February next. The most tender stage in blossoming and the development of the young fruit is shortly after the dropping of the clay or husk.
The blossom becomes more and more tender as it opens. The blossom appear before the foliage develops and the first leaves appear about the time the last petals fall depending upon the variety and season.
Flowering takes place in very early season occurring between January and April depending on the cultivar. Flowers are hermaphrodite with white or pink petals, 5 sepals, a single and unicarpel pistil which usually contains 2 ovules in orthotropic position and 20-40 stamens.
The almond fruit is an egg-shaped drupe with a sigmoid growth pattern. Fruit development stops at 70-75 days after blooming. The pericarp (hull) is almost always thin and may be pubescent. In July it begins to split open freeing the endocarp. The endocarp contains one or two kernels varying in size weighing from 0.5- 1.5 g with brown integuments at maturity.
Most almond varieties are self-unfruitful and as such cross pollination is necessary. Generally any two varieties with over-lapping flowering period intercross and set good fruit if climatic conditions are favourable but certain cases of inter-sterility are also reported. A few such as Taxas and Languedoc, Non-pareil and I.X.L., California Paper Shell and I.X.L., Jordanalo and Harpareil are intersterile. Other varieties can cross-pollinate each other if their flowering period coincides.
On account of the acute problem of self-unfruitfulness, suitable pollenizers need to be provided right at the time of plantation. An efficient arrangement of the pollenizing varieties is to plant these at every third position in every third row. This means that no tree of the main variety is more than one tree away from the pollenizer tree. In some cases complete rows of the pollenizing variety are planted.
For obtaining proper fruit set, two or more cross compatible varieties should be planted in alternate rows. It is further evident that to obtain good fruit set and yields, the presence of honey bees is essential in the flowering season. Usually one or two colonies of honey bees per hectare, but four or five colonies will ensure good pollination even during less favourable seasons with lower temperatures, rain or wind.
Training and Pruning of Almonds:
At the time of planting, head back the tree to one meter above the ground level. Allow the lowest branch at 0.6 m from the ground. The plant should be trained to central modified leader system. Select 3-4 main scaffolds 15 – 20 cm apart spirally in order to produce a good framework of the tree. The crotch angles of the scaffold limbs should be 45 – 60°. In weak crotches, the branches should be tied by strong tying material with pegs.
The almond fruit is borne largely on short spurs. However, a small percentage is also borne on one-year old wood. The spur remains productive up to five years. In order to renew about one-fifth of fruiting wood every year it is a practice to stimulate new shoots by pruning. Amount of pruning depends on the previous crops, efficiency of pollination, kind of fertilization, cultivars, tree vigour and climate.
The young bearing trees should make an annual extension growth of 25-50 cm and older trees 20-30 cm. The almond should not be pruned severely, firstly because it never over bears and secondly its foliage is sparse enough to permit enough light to reach every part of the tree. The pruning consists most of thinning of branches rather than heading them back.
Reinvigorating pruning is carried out only when trees are old and unproductive but healthy. The main branches can be cut back and many new shoots will grow out to replace them in the spring.
Harvesting and Handling the Fruits of Almond:
Almonds become ready for harvesting in the hills from July-September. In subtropical areas, the harvesting may be done in June. The thin leathery hull or husk in almond is non- edible. In Kashmir harvesting season starts by the end of July and lasts for 10-15 days. Dehulling of in-shell harvested almonds is done by engaging labour for the purpose.
One labourer can dehull 10-12 kg of almond daily. Dehulled almonds are spread over mats for drying and they lose 20-50 percent weight in the drying process. The dry nuts are usually graded into two categories viz. thin-shelled and hard-shelled and sent to markets.
Normally, the harvesting should be started when the hulls split and before the nuts begins to fall. At harvest hull colour changes from green to yellow with cracks or splitting at suture starting from pedicel end. A sheet of cloth is spread under the tree and the nuts are made to fall by giving the branches a vigorous shaking or jarring.
The more persistent nuts are knocked off by striking the branches with bamboo poles, taking care not to injure the bark of branches. The nuts are then dried in the sun for a short time. Hard-shelled varieties are bleached with sulphur fume which makes the shells bright and improves their market value.
The nuts grown in Punjab have thin and papery shells. The yield of kernels from these nuts is about 60 per cent in Almond Hybrid-15, 72 per cent in H.P. Selection 10, 54 per cent in California Paper Shell and 46 per cent in Pathick’s Wonder. The kernels are free from bitterness and are very tasty and rich in flavour.
The yield range 3 to 6 kg of nuts per plant. Usually, they are between 3 to 4 kg in varieties of good nut quality. In Kashmir, several trees yield 10-20 kg nuts each at Hariparbat, Tral, Noorpara, Zaboora, Khunmoh etc.