Cashew tree ∗ The big guide from A to Z (kidney tree)

Characteristics

• Scientific name: Anacardium occidentale
• Family: Sumac family (Anacardiaceae)
• Synonyms: cashew tree, kidney tree
• Occurrence: tropics
• Growth type: deciduous tree
• Growth form: broad crown
• Growth height: 10 m to 12 m
• Leaves: obovate, evergreen
• Flower: panicle
• Fruit: drupe
• Root: taproot
• Hardiness: sensitive to frost

growth

Where do cashew nuts grow? Of the cashew tree is an evergreen deciduous tree with high economic value in its tropical native regions. Anacardium occidentale is grown primarily for its tasty, kidney-shaped seeds. Cashew nuts are a popular snack in this country. Hobby gardeners in German-speaking countries appreciate the exotic cashew tree as a decorative container plant, which, with good care, allows you to harvest your own crunchy cashew nuts. A look at the following characteristics of growth provides revealing details:

• growth type: evergreen, tropical deciduous tree with yellowish pink flower spikes, edible fruits and seeds.
• growth habit: broad-spreading, richly branched crown.
• growth height in the habitat: 10m to 12m
• Growth height as a container plant: 2m to 3m
• root system: Taproot with extensive lateral roots.
• Horticulturally interesting properties: medium to demanding care, needs warmth, tolerates pruning, non-toxic, no second cashew plant required for pollination.

digression

Largest cashew tree in the world

blossom

The prologue for a rich cashew harvest is the summer flowering period with these flower characteristics:

• inflorescence: long-stalked, 20 cm to 25 cm long panicle with numerous, fragrant individual flowers.
• single flower: fivefold, hairy (5 ovate sepals, 5 oblong, reflexed petals.
• flower color: greenish-yellow to reddish.
• flower ecology: andromonoceous (male or female and hermaphroditic flowers are on a tree).
• pollination: bees, flies, wind.

fruit

If you are familiar with these fruit properties, you will know the right answer to the question: How do cashew nuts grow?

• fruit type: single-seeded drupe.
• fruit shape: 5 cm to 10 cm long, thickened, paprika-shaped fruit stalk (cashew apple), on which a 2 cm small, kidney-shaped structure hangs (cashew fruit).
• fruit color: cashew apple with yellow-orange-red skin, drupe with greenish-brownish skin.

The cashew apple is a dummy fruit whose seedless pulp is suitable for consumption. The actual, reproductive cashew fruit is the boxer glove-like appendage on the thickened fruit stalk, popularly known as the elephant louse. Inside are the edible seeds known as cashew nuts or cashew nuts.

cashew nuts

Cashew nuts inspire gourmets all over the world with their mild, sweet and nutty taste. The kidney-shaped kernels are often roasted, salted or eaten raw. These valuable ingredients make cashew nuts a healthy snack for the whole family:

Worth knowing detail: With a proportion of 238 mg amino acid tryptophan per 100 g, cashew nuts boost the production of the neurotransmitter serotonin. For this reason, eating the delicious nuts puts you in a good mood. The only downside is the poisonous shell that envelops each cashew seed. Since raw cashew nuts are also slightly toxic, the nuts are only sold peeled and roasted.

Sheet

The richly branched crown of a cashew tree bears evergreen leaves with these characteristics:

• leaf shape: obovate, entire, rounded to obtuse, sometimes slightly indented.
• sheet size: 8 cm to 15 cm long, 6 cm to 12 cm wide.
• leaf color: leathery green, evergreen, leaf veins clearly visible.
• arrangement: alternate

Plant cashew tree

A ready-to-plant cashew tree can only be bought sporadically in Germany. Anyone who finds what they are looking for, for example at flora-toskana.com, pays around 20 euros for a 18 cm to 20 cm small specimen. The planting succeeds more cheaply and with a gardening experience factor after one sowing of cashew seeds. These planting tips explain how and where to properly plant a kidney tree:

sowing

Commercially available cashew nuts are not suitable as seeds. Immediately after harvesting, the peeled seeds are roasted and cannot germinate. You can buy certified cashew seeds from specialist retailers for around 1 euro per seed. The following instructions explain step by step how to grow a cashew tree from seeds yourself:

1. Sow cashew seeds no later than 6 weeks after receipt.
2. Roughen the seed coat with fine sandpaper or a nail file.
3. Soak the seeds in room-warm water for 12 to 24 hours.
4. Fill a seed pot per core with a mix of seed substrate, unfertilized coconut soil and lava granules.
5. Put the soaked seeds halfway into the ground (indentation points down, seed dome is exposed).
6. Moisten the substrate and seeds with a fine spray of soft water.
7. Place the seed pots in the heated greenhouse.
8. Keep slightly moist in a bright window seat at a constant 28° Celsius.

Under ideal conditions, germination takes four to six weeks. Cashew seedlings are further cultivated at a cooler 18° to 22° Celsius.

planting

These tips & tricks explain what really matters when planting cashew trees:

• The tub is deeper than it is wide to allow the taproot to develop undisturbed.
• A drainage made of potsherds on the bottom of the bucket prevents waterlogging.
• Optimal culture substrate: premium potting soil without peat, fertilized coconut soil as a peat substitute, lava granules(€14.00 at Amazon*) or expanded clay(€19.00 at Amazon*) and coarse sand.
• A lukewarm water bath prepares the root ball for planting.
• The planting depth in the tub corresponds to the planting depth in the seed pot or purchase container.

Location

The ideal location for a cashew tree as a container plant simulates tropical conditions:

• Sunny, light to semi-shady location with high humidity.
• From spring to autumn with temperatures from 20° Celsius.
• In winter with normal room temperatures around 18° Celsius.
• Minimum temperature: 15° Celsius

Recommended locations are heated conservatories and light-flooded living and working spaces. In contrast to most tropical potted plants, the summer balcony is not suitable for a cashew tree.

Cultivate cashew tree

A cashew tree is moderate to demanding to care for. The water supply requires a sure instinct. A good sense of proportion is desirable for the nutrient supply. With inappropriate wintering, the kidney tree indignantly sheds its evergreen leaves. By comparison, trim maintenance is a breeze. The following care tips explain important details:

Pour

• Maintain consistent soil moisture all year round without waterlogging or drought stress.
• Irrigation water quality: warmed up, room temperature, filtered rainwater or decalcified tap water.
• Spray evergreen leaves regularly with soft, lukewarm water.

Fertilize

• Cashew tree from April to September every 14 days fertilize with a liquid fertilizer for tropical potted plants.
• Do not fertilize a cashew plant that has been weakened by diseases, pests or care errors.
• Pour clear water before and after fertilizing.

hibernate

• Cashew trees spend the winter light and warm at an ideal 18° Celsius.
• Maintain even soil moisture while adjusting watering frequency to winter conditions.
• Do not fertilize from October to March.

To cut

• Do not prune the cashew tree in the first few years.
• If necessary, in the spring withered flowers, fruit mummies and dead leaves from the treetop remove.
• Thin out older treetops occasionally in February or March.
• Extra tip: it is possible to cut back individual overly long branches protruding from the crown at any time.

repot

As a container plant, a cashew tree grows much more slowly than in its tropical home regions. Every two to three years you should repot the cashew tree into a larger bucket with fresh soil. The best time is in early spring, just before fresh sprouting begins.

Diseases, pests, care errors

Far from its tropical homeland, a cashew tree is not immune to diseases and pests. Negligence in care can also weaken a cashew tree. The following table draws attention to common damage patterns, names typical causes and refers to effective countermeasures:

The important thing to note is that you do not fertilize a damaged cashew tree until it has recovered. Otherwise, unused fertilizer salts accumulate in the substrate and cause irreversible damage to the sensitive taproots.

Popular Varieties

Apart from the original species Anacardium occidentale, no cashew tree varieties are available in Europe.

FAQ

Are cashew nuts poisonous?

Freshly harvested cashew nuts are slightly toxic and not suitable for consumption. The peel contains anacardic acid, a toxic oil that causes painful skin irritation. Furthermore, raw kernels contain various substances that are harmful to health. Steaming at high temperatures allows the hard shell to open and dissolve the toxins in the core. For this reason, you can only buy peeled and roasted cashew nuts in the grocery store. Untreated, raw cashew nuts are only used as seeds.

How is a cashew tree pollinated as a container plant?

In the tropics, bees, flies and ants take care of the pollination of a cashew plant. Hobby gardeners take on this task in closed living rooms, greenhouses and conservatories. Using a soft hair brush, stroke each flower to transfer the pollen from the male flowers to the female and hermaphrodite flowers.

Where can you buy a cashew tree?

Shopping sources for a ready-to-plant cashew tree are few and far between. We looked around for you in the German-speaking area and found these providers: flora-toskana.com with a well-stocked online shop and an on-site sale in Kempten. On Amazon, the German specialist retailer greenfuturepflanzenhandel occasionally offers cashew plants, either as a 5-10 cm seedling or as a 15-20 cm young plant.