I hadn’t really thought about cloves being dried flower buds until researching this story. And did you know that cloves, Syzygium aromaticum, are closely related to lillypilly and eucalypts? I’m talking with spice expert, Ian Hemphill from Herbies, about the fascinating history of cloves and their part in the fortunes of the Dutch East India Company, as well as their origins in ‘The Spice Islands’ a handful of tropical Indonesian islands in the Banda Sea.
Cloves were as important a trading commodity in the 15th century as oil is today and the famous explorer and merchant Magellan’s company made huge profits from bringing cloves back to Europe.
[Ian’s tip when buying ground cloves is to check the powder is fine, dark brown and with a pungent aroma, or you might be buying 2nd grade cloves with added ground up stem. Ground cloves have a very long shelf life of several years]
The clove tree is a 8-10m (25-33ft), tropical evergreen tree. Clove flower buds change over 5-6 months from green to pinkish-red, then are picked and sun dried for 4-5 days. The buds are quite waxy and both the flowers and leaves are very similar to an Australian gum tree, showing their Myrtaceae connection. As the buds dry, they turn brownish-black and create a volatile oil called eugenol (also found in basil), which makes it a wonderfully aromatic spice for cooking and also a strong natural anaesthetic and antiseptic.
[Ian’s recipe hint: use a pinch of cloves in your next pasta dish. It’s often a chef’s secret ingredient to make it something extra special!]
Cloves are also grown in India, Sri Lanka, Madagascar, Africa and many tropical countries. The islands of Zanzibar and Pemba off Tanzania on Africa’s eastern coast have large clove plantations and it’s said you can smell the cloves for kilometres out to sea.
Clove fruits are usually allowed to drop naturally from the tree and then sown straight into the growing medium. Otherwise, they need to stay moist and be sown within one week to germinate successfully, with the fruit first soaked overnight and then the fleshy pericarp removed by rubbing with sharp sand. Storing seeds in plastic bags will make them quickly rot and small seedlings are very prone to fungal attack.
Germination takes about 6 weeks and the seedlings are very delicate and slow growing. Don’t even think about potting them up until they’re about 25cm (9in) high, which may take up to 6 months! Some growers recommend letting the growing medium dry out the day before transplanting to try to keep the small, fragile root ball intact. Grow them on in the shade for another 18 months before planting in the garden. Cloves could potentially be grafted onto compatible Myrtaceae plants but this has not been commercially explored.
Although you can grow a clove tree in subtropical zones, it may not flower in cooler temperatures as it needs temperatures above 10 degrees C (50F) and consistently high humidity. You can grow it as an indoor plant or in a greenhouse if you can keep the humidity high enough – indoors you could try a terrarium-style growing environment as long as the potting mix can drain well.
Clove trees need plenty of water throughout the year and protection from strong wind. Volcanic and rich loam soils with added organic matter will give the best results, although a seed-grown tree will still take about 7 years to flower. It grows compatibly with either pepper or coffee, or bananas can be used as a protective nurse plant while the seedlings establish. Clove trees are often quite twiggy, which also results in more flower-bearing flushes of growth.
Commercial clove trees are fertilised twice a year with both complete mineral fertiliser and also manures.
[Fun tip from Ian: make a clove studded orange. The preservative nature of the cloves can keep the orange from rotting for many years]
Clove trees can be attacked by stem borers and also mealy bugs and scale, however fungal attack is by far the most common cause of plant disease and death, usually at the seedling stage but also even in mature trees. As clove trees have a fine, hairlike root system, mature trees can also quickly collapse and die from drying out. Although the fungi that infect clove trees have been identified, the spreading vector is not yet understood.
Where to buy clove trees:
Australia – Daley’s Fruit occasionally has potted clove trees for sale.