Germination temperature
Warm tropical weather; cashew is killed by frost. Sow in the hot pre-monsoon season.
Nut tree growing guide
Cashew is easy to raise from fresh seed nuts in a warm, frost-free climate: soaked nuts sown stalk end up usually sprout in one to three weeks. This guide follows Kerala Agricultural University's nursery method and covers planting, frost and the pests that matter.
Warm tropical weather; cashew is killed by frost. Sow in the hot pre-monsoon season.
2-3 cm (3/4-1 1/4 in), stalk end up.
7-10 days in dry weather, 15-20 days in the monsoon.
Not needed to germinate; full sun for trees.
Soak seed nuts in water for 18-24 hours (overnight at least).
Sow one nut per polybag, plant out at the start of the monsoon.
Sow raw, unroasted nuts still in their shell. Kerala Agricultural University (KAU) selects mature, medium-sized nuts that sink in water after 2-3 days of sun drying and rejects floaters. Use nuts less than a year old: World Agroforestry reports that open-stored seed falls to 50% viability after 10 months and is dead after 13-14 months. The shell contains a poisonous oil, so do not crack or bite it and wash hands after handling.
Not needed. Soaking is enough to start germination.
Not needed. Cashew is a tropical tree with no chilling requirement.
Recommended. KAU soaks seed nuts for 18-24 hours before sowing seedlings, and overnight for nuts raised as grafting rootstock.
Sow in warm weather. KAU sows in May in Kerala; World Agroforestry lists a mean annual temperature range of 17-38 °C (63-100 °F) for the species and notes that frost is harmful. In cooler countries keep pots in a heated greenhouse or warm room.
2-3 cm (3/4-1 1/4 in) deep, one nut per bag with the stalk end facing up.
KAU fills 25 x 15 cm (10 x 6 in) polybags with 16-20 drainage holes with red soil, river sand and compost 1:1:1; for simple seedlings garden soil in 20 x 15 cm (8 x 6 in) bags is used.
Water right after sowing and then daily, but avoid excess irrigation; damping-off is a known seedling disease.
No light needed to germinate. Put the bags in full sun once seedlings emerge.
KAU reports 7-10 days for soaked seed, 8-10 days in dry months and 15-20 days in the monsoon.
Seed-grown cashew forms a strong taproot, so raise it in bags and plant out young without breaking the root ball. KAU plants in 50 x 50 x 50 cm (20 in) pits in June-July, 7.5 m (25 ft) apart on poor soils and 10 m (33 ft) on rich, deep or sandy coastal soils.
Keep weeds down in the dry months to save soil moisture for young plants. Seedlings raised as rootstock are ready for softwood grafting 50-60 days after germination; grafts are planted at 5-6 months with the union about 2.5 cm (1 in) above the soil.
Cause: old or light nuts. Fix: sow nuts under a year old that sink in water.
Cause: damping-off in wet, poorly drained mix. Fix: use free-draining bags with plenty of holes and avoid overwatering.
Cause: tea mosquito bug, the most serious cashew pest in Kerala. Fix: watch new flushes and flowering from October to February and follow local extension spray advice; avoid sprays toxic to bees during flowering.
Cause: cashew stem and root borer. Fix: inspect trunks January-May, cut out grubs without removing more than half the bark circumference, and remove dead or heavily infested trees.
Cause: frost. Fix: grow cashew only where it stays frost-free, or keep it in a container under cover.
Cashew yields best on well-drained red sandy loams and light coastal sands and tolerates poor laterite soils. KAU lists heavy clay, poor drainage, very low temperature and frost as unsuitable.
Cashew is cross-pollinated, so seed-grown trees vary in nut size and yield. For a known variety, graft a selected scion onto your seedling.
World Agroforestry notes that rainfall distribution matters more than total rain and that nuts keep best when they mature in a dry period.
Seed-grown trees normally start flowering at 3-5 years.
Soak and sow cashew seed nuts in warm weather for a sturdy tropical nut tree.
No. Shop cashews are shelled and processed kernels. Only raw seed nuts in their shell can germinate.
Sow it 2-3 cm deep with the stalk end facing up, as Kerala Agricultural University recommends.
Only in a warm greenhouse or conservatory. Frost damages it, and it needs high temperatures to grow and fruit.
Seedlings normally begin flowering in 3-5 years; nut size and yield vary from tree to tree.