Papaya Seedlings: Why You Grow Several and Cull the Males

You cannot tell the sex until it flowers

A papaya is one of three things: male, female, or bisexual (usually called hermaphrodite). A male plant produces pollen and nothing else, and it will stand there growing leaves for the rest of its life without ever setting a single fruit. A female plant fruits if pollen reaches it. A bisexual plant carries both parts in the same flower, pollinates itself, and is the one most home growers actually want because it needs no partner.

Nothing about the seedling tells you which one you have. Leaf shape, vigor, stem thickness, color, the speed it grows, the size of the first true leaves: none of it correlates with sex. Growers stare at seedlings looking for a tell every season and there is no tell. The plant declares itself only when the first flower buds appear in the leaf axils, which is typically four to six months after germination, and by then it is a stem three to six feet (0.9 to 1.8 m) tall that has occupied a planting spot all season.

So the method is numerical rather than diagnostic. You germinate more seedlings than you need, plant them in small clusters, wait for the flowers, then remove everything that turns out to be male and keep the best fruiting plant in each cluster. This feels wasteful the first time you do it. It is simply how the crop works, and skipping it is how people end up with one handsome plant that flowers beautifully every year and never gives them fruit.

How many seedlings per spot

The number comes from probability. Seed saved from a bisexual fruit tends to give roughly one male in four, with the rest split between female and bisexual; seed from a female fruit pollinated by a male gives about half males. Three or four seedlings in a cluster reduces the chance of ending up with an all-male spot to something you can live with, and five is not excessive if the seed source is unknown.

Plant the cluster tight, six to twelve inches (15 to 30 cm) apart, in one prepared planting position rather than spread across the bed. They will crowd each other for a few months, which is fine, because you are going to remove most of them. Spreading them out instead means every hole you prepared and fed is committed to a plant that may be useless.

Germinating and raising them

Papaya seed germinates on warmth and little else. Below 68F (20C) it sulks and rots; at 77 to 86F (25 to 30C) it comes up in one to three weeks. The gelatinous coat around each seed contains germination inhibitors, so rub the seeds between your fingers under running water until the film is gone before sowing. Fresh seed from a ripe fruit is far more reliable than seed that has sat in a packet for a year.

1. Clean and sow shallow Rub off the gel coat, then sow half an inch (1 cm) deep in a free-draining mix. Sow two or three seeds per cell or pot so you are not left with gaps; papaya germination is rarely a hundred per cent even with fresh seed.
2. Keep it warm, not wet Hold the mix at 77 to 86F (25 to 30C) and merely damp. Seedling papaya damps off and rots at the base with very little provocation, and a tray sitting in cold wet compost will lose the lot before anything emerges.
3. Move them on early Papaya makes a fast, brittle taproot that resents disturbance. Pot on or plant out while the seedling is still small, six to ten inches (15 to 25 cm) tall, and keep the rootball intact. A seedling left to spiral in a small pot never grows away properly afterwards.
4. Plant the cluster out warm Set the whole cluster out only once soil is reliably above 68F (20C) and no cold snap is coming. Papaya stalls below that and rots at the collar if cold and wet arrive together.

Reading the first flowers and thinning

Watch the leaf axils from about four months on. The difference is easy once you see it. Male flowers hang in long branching sprays, sometimes a foot (30 cm) or more, on thin stalks, with a slim tube and no swelling behind the petals. Female flowers sit tight against the trunk, singly or in small groups, on almost no stalk, with an obvious green bulb at the base that is the future fruit. Bisexual flowers also sit close to the trunk but are more elongated, with visible stamens inside and a slimmer bulb behind them.

Once you have read the cluster, cut the males off at ground level and take out any weak or lopsided plant, leaving one strong fruiting plant per position. Do this promptly. Every week a doomed male stays in the cluster it takes water, feed and light from the plant you are keeping. The one reason to keep a single male somewhere in the garden is if all your keepers turned out female, in which case one male within a hundred feet (30 m) pollinates the lot.

Sex can shift under stress. Bisexual plants sometimes throw male-only flowers through a hot dry spell and return to normal when conditions ease, so do not condemn a plant on one flush of flowers in the middle of a heatwave.

What to write down now

Note the sowing date, the fruit or source the seed came from, and how many days each cell took to emerge. Then, when the flowers open, record the position of every plant in the cluster and what sex it turned out to be. That single record is worth more than anything else you will write about papaya, because it tells you next season whether that seed source gives you mostly bisexual plants (sow three) or a coin toss (sow five).

Also note the date of the first flower on the plant you keep. Papaya runs to a fairly fixed schedule from flower to ripe fruit in a given climate, so once you have one season logged you can predict your own harvest window instead of guessing at it.