Clove trees are the tropical source of the famous, smoky flavored spice that’s so popular with ham and autumnal desserts. It’s tempting to want to have one of your very own, but their extreme sensitivity to cold makes it impossible for most gardeners to grow outdoors. This brings up the important question: can you grow cloves in containers? Keep reading to learn more about caring for grown clove trees.
I. Appearance and Characteristics
Cloves are the aromatic flower buds of a tree in the family Myrtaceae, Syzygium aromaticum. They are native to the Maluku Islands, or Moluccas, in Indonesia, and are commonly used as a spice, flavoring, or fragrance in consumer products, such as toothpaste, soaps, or cosmetics.
The word clove, first used in English in the 15th century, derives via Middle English clow of gilofer, Anglo-French clowes de gilofre and Old French clou de girofle, from the Latin word clavus “nail”. The related English word gillyflower, originally meaning “clove”, derives via said Old French girofle and Latin caryophyllon, from the Greek karyophyllon “clove”, literally “nut leaf”.
The clove tree is an evergreen that grows up to 8–12 metres (26–39 ft) tall, with large leaves and crimson flowers grouped in terminal clusters. The flower buds initially have a pale hue, gradually turn green, then transition to a bright red when ready for harvest. Cloves are harvested at 1.5–2 centimeters (5⁄8–3⁄4 in) long, and consist of a long calyx that terminates in four spreading sepals, and four unopened petals that form a small central ball.
Clove stalks are slender stems of the inflorescence axis that show opposite decussate branching. Externally, they are brownish, rough, and irregularly wrinkled longitudinally with short fracture and dry, woody texture. Mother cloves (anthophylli) are the ripe fruits of cloves that are ovoid, brown berries, unilocular and one-seeded. Blown cloves are expanded flowers from which both corollae and stamens have been detached. Exhausted cloves have most or all the oil removed by distillation. They yield no oil and are darker in color.
II. How to Grow and Care
Sunlight
Clove trees will grow best in full sun to partial shade. Young trees prefer to receive some shade.
Temperature and Humidity
Clove trees require a humid tropical or subtropical climate. Constant temperatures above 50 degrees Fahrenheit are essential with ideal temperatures being in the range of 70 to 85 degrees Fahrenheit.
Watering
These plants require constant moisture. Some gardeners opt for a drip irrigation system for best results, particularly during the summer months when the plants might require additional watering. Just be sure that the soil doesn’t become waterlogged or too soggy, as these conditions can lead to root rot. The clove tree will require the most frequent watering during the first three to four years of its life.
Soil
If the soil has good drainage, the clove plant will thrive in rich, loamy soil (preferably with organic matter).
Fertilizing
Clove trees will grow and produce best when provided with regular fertilization. Well-composted manure can be applied from May through June. In the early fall months, fertilizer can be applied in shallow trenches dug around the plant.
Pruning
A clove tree does not require extensive pruning, though its branches can be cut back to the desired height after harvesting. Remove dead or damaged branches and dead leaves at any time.
Propagation
A clove tree does not require extensive pruning, though its branches can be cut back to the desired height after harvesting. Remove dead or damaged branches and dead leaves at any time.
How to Grow From Seed
It’s best to propagate seeds in the middle of the summer. Seeds should be planted immediately after harvesting. After fruits are allowed to ripen on the tree, they will naturally fall and their seeds can either be soaked in water overnight or sown directly into the garden.
Don’t cover seeds with soil, they require light to germinate. If you are germinating the seeds in a container, cover the pots or seed tray with a piece of plastic to increase the humidity levels. The seed germination process will take about six weeks.
Use fresh seeds because if the seeds are dried out they are less likely to germinate. If you are not able to plant clove seeds immediately, it’s best to store them in soil until the time is right.
Growing in Containers
Clove trees can be grown in containers, though they will not grow as tall as when planted outdoors. Containers should be at least 18 inches in diameter and have a proper drainage system.
The pot or container can be filled about two-thirds full with moist (but not soggy) soil, and seeds can be placed directly on top of the soil. If a clove seed is already rooted, then press it gently below the soil surface.
The container should be kept in a bright spot with access to indirect sunlight, preferably in a room with a temperature that remains consistently between 65 to 80 degrees Fahrenheit.
Pests and Diseases
Common Pests and Plant Diseases
Several diseases and pests can plague clove trees. Perhaps the most serious is Sumatra disease, a bacterial infection that causes the trees to begin to die from the top down. While there is no cure for the disease, its progression can be slowed by an injection of the antibiotic oxytetracycline. If the disease shows up around your clove tree, you might want to use an insecticide that fights insects in the Hindola species, which are thought to be the cause of the issue.
Clove trees can also suffer from eucalyptus canker, which happens when a fungus enters a wound. The best step here is prevention. Avoid nicking the tree with tools or equipment and if the bark is punctured, treat them with an antifungal paste.
In terms of pests, clove trees can be visited by coconut scale bugs, which are flat and oval and resemble a scale. If you witness pale yellow spots on leaves or entire leaves turning yellow and brown and dropping too early, this could be the cause. They can also fall prey to the Oriental fruit fly, soft scale bugs, and nematodes. Treatments include, respectively: bagging the tree’s fruits when they emerge, using horticultural oil; and solarizing the soil.
Common Problems
Aside from the issues mentioned above, there are few other problems that affect clove trees. Just be careful to keep the soil consistently moist without drowning the trees because too much water could lead to root rot.
III. Uses and Benefits
- Culinary uses
Cloves are used in the cuisine of Asian, African, Mediterranean, and the Near and Middle East countries, lending flavor to meats (such as baked ham), curries, and marinades, as well as fruit (such as apples, pears, and rhubarb). Cloves may be used to give aromatic and flavor qualities to hot beverages, often combined with other ingredients such as lemon and sugar. They are a common element in spice blends (as part of the Malay rempah empat beradik –”four sibling spices”– besides cinnamon, cardamom and star anise for example), including pumpkin pie spice and speculaas spices.
In Mexican cuisine, cloves are best known as clavos de olor, and often accompany cumin and cinnamon. They are also used in Peruvian cuisine, in a wide variety of dishes such as carapulcra and arroz con leche.
A major component of clove’s taste is imparted by the chemical eugenol, and the quantity of the spice required is typically small. It pairs well with cinnamon, allspice, vanilla, red wine, basil, onion, citrus peel, star anise, and peppercorns.
- Non-culinary uses
It is often added to betel quids to enhance aroma while chewing. The spice is used in a type of cigarette called kretek in Indonesia. Clove cigarettes were smoked throughout Europe, Asia, and the United States. Clove cigarettes are currently classified in the United States as cigars, the result of a ban on flavored cigarettes in September 2009.
Clove essential oil may be used to inhibit mold growth on various types of foods. In addition to these non-culinary uses of clove, it can be used to protect wood in a system for cultural heritage conservation, and showed the efficacy of clove essential oil to be higher than a boron-based wood preservative. Cloves can be used to make a fragrant pomander when combined with an orange. When given as a gift in Victorian England, such a pomander indicated warmth of feeling.
- Potential medicinal uses and adverse effects
The use of clove for any medicinal purpose has not been approved by the US Food and Drug Administration, and its use may cause adverse effects if taken orally by people with liver disease, blood clotting and immune system disorders, or food allergies.
Cloves are used in traditional medicine as an essential oil, which is used as an anodyne (analgesic) mainly for dental emergencies and other disorders. There is evidence that clove oil containing eugenol is effective for toothache pain and other types of pain, and one review reported the efficacy of eugenol combined with zinc oxide as an analgesic for alveolar osteitis. Clove essential oil may prevent the growth of Enterococcus faecalis bacteria which is often present in a root canal treatment failure.
Studies to determine its effectiveness for fever reduction, as a mosquito repellent, and to prevent premature ejaculation have been inconclusive. It remains unproven whether blood sugar levels are reduced by cloves or clove oil. The essential oil may be used in aromatherapy.
