Psidium guajava Seeds | Pink Fruit
LATIN NAME: Psidium guajava
COMMON NAME: Guava, Pink Guava, Common Guava
Plant Profile
Guava is a small evergreen tree or large shrub of the myrtle family, usually three to eight metres in a garden, though old specimens in the tropics can reach ten. The bark is smooth, pale brown and peeling in long flakes, the leaves are opposite, oblong, deeply veined and aromatic when crushed, and the whole plant has the slightly untidy, eager look of a species that grows fast and fruits young.
The flowers are white, about two and a half centimetres across, with a prominent brush of stamens, and they are borne singly in the leaf axils. They are pollinated by bees and by a range of small insects, and a single tree can set a heavy crop without a partner, which is one reason the species has followed people around the tropics so successfully.
The fruit is a berry, round or pear-shaped, green turning yellow-green as it ripens, with a thin skin, a layer of soft, sweet, strongly aromatic flesh and a central mass of small, hard seeds. The pink-fleshed forms, which this page covers, get their colour from lycopene, the same pigment that colours a tomato, and they are generally sweeter and less acid than the white-fleshed types.
The species is native to Mexico, Central America and northern South America, and it was carried across the tropics by the Spanish and Portuguese within a century of contact. It now grows wild and cultivated from Florida to Fiji, and it is one of the most widely planted fruit trees in the world, valued for its speed, its tolerance and its vitamin content rather than for its beauty.
Science & Biotechnology
The vitamin C content is the fact that made guava famous, and it is not exaggerated. A hundred grams of fresh fruit contains roughly two to four times the ascorbic acid of an orange, with the concentration highest in the skin and in the outer flesh, which is exactly the part that is often discarded. The pink flesh adds lycopene and a suite of carotenoids, and the fruit also carries dietary fibre, potassium and a range of phenolic compounds.
Guava leaves are a separate pharmacology. They contain flavonoids, tannins and triterpenes, and leaf decoctions are used across the tropics for diarrhoea and for blood sugar control. Clinical work on guava leaf extract has shown modest reductions in post-meal glucose in small human trials, and there is reasonable evidence for antidiarrhoeal activity, largely attributed to the tannins and to the flavonoid quercetin. It is not a treatment for diabetes, and it should not replace one.
The species is also a study organism for invasiveness. It produces enormous numbers of seed, the seed passes through the gut of birds, bats, pigs and cattle, and it germinates readily in disturbed ground. On oceanic islands and in open habitats it can form dense thickets that exclude native vegetation, and it is listed as invasive in parts of Hawaii, Fiji, the Galapagos and several Indian Ocean islands.
Taxonomically the genus is messy, with a long history of hybridisation and of cultivated selection, and the pink and white flesh types are forms of a single variable species rather than separate taxa. Named cultivars are propagated by grafting or by air layering, because seed does not breed true for fruit quality.
Uses & Benefits
The fruit is eaten fresh, stewed, made into jam, jelly, paste and juice, and in much of Asia it is eaten half-ripe with salt and chilli. The pink-fleshed types are preferred for juice because of their colour and sweetness, and the fruit is a major commercial crop in India, Mexico, Brazil, Thailand and China. In a garden, a single tree will fruit within two or three years of sowing, which is unusually fast for a fruit tree.
The leaves are used medicinally as a tea, and the bark and roots appear in the folk medicine of Central America for diarrhoea, wounds and fever.
There is a practical caution for growers in citrus and fruit-fly regions. Guava is a preferred host of the Mediterranean, oriental and Mexican fruit flies, and in areas where those pests are managed, fallen fruit must be collected and destroyed to break the cycle. The tree is also a host of guava rust, a fungal disease that threatens eucalyptus plantations, and planting it near forestry estates is discouraged in some countries.
Ecologically, the flowers feed bees and the fruit feeds birds and bats, which is precisely why the species spreads. In a garden that is not near sensitive natural habitat, that is a benefit; near one, it is a liability, and the difference should be understood before planting.
Growing from Seed
Sow fresh seed, cleaned of pulp, in a loose, free-draining mix at about one centimetre depth, and keep at twenty-two to twenty-eight degrees in bright light. Germination is usually two to five weeks, and fresh seed germinates far better than seed that has dried. The seed coat is hard, so a light scarification or a day of soaking speeds things up.
Grow the seedlings on in full sun, in a free-draining soil, and pot them on as they grow. Plant out once the root has filled the container and the risk of frost has passed, into a sheltered, sunny position. Water through the first two summers, then only in drought. Young trees benefit from tipping to encourage branching, and a light annual prune keeps the canopy open and the fruit within reach. In cool climates the plant can be grown in a large container and moved under cover for winter, though the crop will be smaller.
Our Take
Guava is one of the most rewarding fruit trees a warm-climate gardener can raise from seed: fast, tolerant, productive and genuinely nutritious. The pink-fleshed forms are the best eating, and a single tree will give more fruit than a family can use. Grow it where it can be kept in bounds, watch for fruit fly, and do not plant it next to a natural area where it does not belong.
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