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Papaya is a fast-growing, sun-loving tropical herb that can yield tasty fruit within a year. It is not tolerant of cold (though other varieties are somewhat frost tolerant) or surface water.
Papaya has several features which make it a staple of the urban guerrilla gardener in tropical areas:
- It is fast growing and yields attractive fruit
- It requires minimal land area and can be planted next to walls
- Seeds are small, plentiful and germinate well enough if simply dropped onto soil
- Its distinctive leaf shape is easily recognised and known
- Its sap makes it unattractive to some livestock (cows?), though goats reportedly eat it
Points to note are:
- It is intolerant of flooding or cold weather
- It requires highly fertile soil and plenty of sun
Papayas grow readily from seed, which can be simply tossed over walls as they are - seedballs may help but are not required for successful germination. Germination percentage is apparently increased by breaking the soft seed coat, though again, though this is not necessary for fresh seeds. For public areas, cultivate a seedling in a nursery until it is tall enough to withstand grazing or other accidental damage before planting out.
Papayas are surface rooters with delicate roots. They are very sensitive to transplanting, so transplant them as little and as carefully as possible. One method is not to plant the seed in a pot, but instead use a thin polythene bag (remembering to puncture it to ensure drainage). When the time comes for transplanting, simply dig a matching hole and place the bag in it, cutting it as you do so, so it can be easily removed.
Dwarf cultivars exists which may have less space requirements, though Robin reports that although possible, it is not easy to get papayas to thrive in containers. Robin recommends it as an educational challenge!
Most papaya cultivars are dioecious, so both males and females are needed to set fruit. Gender is easily determined for plants once they start to flower. Males flowers are long and thin, and grow in large numbers on stalks from the stem. Female flowers are rounder, and grow close to the stem. After fertilization, female flowers develop into fruit which hangs on thick stalks next to the stems.
Since females fruit earlier and produce sweeter fuit, they are preferred. Plant gender is not fixed but may vary according to plant stress. Male plants are often decapitated in a deliberate effort to stress the plant and cause it to develop female flowers. This sometimes causes more than one meristem to become apically dominant, resulting in branching, which is otherwise very rare in most papayas.
In the right spot, papayas need little care. The ideal spot is atop a mound of well drained, fertile soil, next to a south-facing white wall (for maximum sunlight), with a adequate wind protection up to a height of perphaps 5 metres. The number and shape of leaves is a pretty good indicator of plant health.
Anywhere which has standing water for more than a day or so is unsuitable for papaya. However, their shallow rooted nature means that building a mound of around 50cm or more in height may be sufficient to allow papaya to flourish.
Papayas have large leaves which transpire a lot of water, so in periods of drought, they will appreciate water, as indicated by a wilting appearance. Soil should be moist but not wet. Be particularly careful to avoid overwatering - especially when temperatures are low. If the soil does not have time to dry properly, you may find the leaves suddenly turning yellow and dropping off due to water stress.
A surface rooters, papayas are good at absorbing nutrients from the base of the stem, so one way to strengthen them is to deposit rotting leaves, fruit peelings and other decaying organic matter at the stem. You should however always leave one side of the plant completely clear of mulch to prevent root rot, and it may be helpful to remove mulch in times of heavy rain to facilitate sun drying of the the base of the papaya (root crown?).
Papayas' large leaves and weak stems makes them very vulnerable to being blown over. If this happens, it need not prove fatal. The main priority is to make sure the stem does not remain on the ground, or it will rot. One option is to tie the stem to a nearby wall or other tree trunk, another is to prop it up, so the top is at least a metre off the ground (to allow room for branches). The trunk will naturally bend towards an upright orientation.
Mealybugs are a common threat to Papaya. Left unchecked, thousands together can overwhelm a plant. This are a short (up to ~5mm) white creatures which locate themselves mainly on the underside of leaves and in othe cracks where they are not vulnerable to rain. There they extract juice from the plant. They exude honeydew, which attracts ants, providing easy diagnosis; if you see ants climbing up the stem, follow them to get the mealybugs. The recommended removal method for mealybugs is simply to remove them from the plant by spraying with water (though be careful not to physically damage the leaves when you do this). Another method is to throw fine ash on the plant. This is not damaging to the plant, but can prove fatal to mealybugs.
Most papayas are susceptible to viruses which can cause leaf curling or other symptoms of distress. These are not treatable but do not generally afflict healthy plants.