Getting it to bloom

Why won't my Watermelon bloom? (and how to make it flower)

Also called water melon (Citrullus lanatus).

About Watermelon

Citrullus lanatus · also called water melon · edible

Watermelon is a heat-loving annual vine grown for large juicy fruit. Needs 80-100 frost-free days at high temperatures. Best with mulch and consistent water. Pet-safe — flesh is non-toxic, but rinds and seeds should be limited.

Watermelon, Citrullus lanatus, was domesticated in northeast Africa around Egypt and Libya; a sprawling, frost-tender warm-season annual vine.

Plant type: edible

Sources: extension.umn.edu, extension.umn.edu

The reasons watermelon isn't blooming

Almost every non-blooming watermelon traces back to one of these, roughly in order of how common they are:

Too little sun — most of these need full sun (or very bright light) to flower well; shade gives leaves, not blooms.
Too much nitrogen feed, driving lush foliage at the expense of flowers (very common with general or lawn feeds).
Heat or cold stress at flowering, or poor pollination, so flowers form but drop without setting.
Irregular watering — drought or waterlogging at the budding stage makes buds abort.
It is still too young or was checked by a transplant and is rebuilding before flowering.

Feeding watermelon a high-nitrogen general feed and growing it in too little sun — you get a big leafy plant and almost no flowers.

The fix — how to get watermelon to flower

Maximise sun. Give watermelon the sunniest spot you have — for most bedding and fruiting plants, more direct light directly means more flowers.
Switch the feed. Move off high-nitrogen feeds and use a higher-potassium "bloom" or tomato-type feed as it comes into flower.
Help it set. Keep moisture steady, avoid temperature extremes at flowering, and encourage pollinators (or hand-pollinate) so flowers turn into fruit.
Water consistently. Keep moisture even through budding and flowering — drought-then-flood swings make buds drop.

Light and feeding do most of the heavy lifting here. Dial in the spot with the light guide for watermelon and get the feeding right with the watermelon fertilising schedule — the wrong feed (too much nitrogen) is one of the most common silent reasons a healthy plant makes leaves instead of flowers.

Bloom season and what to expect

Watermelon flowers through its warm growing season and, with good pollination, follows each flush of flowers with the crop — expect a steady run rather than one burst.

Post-bloom care so it flowers again

Keep feeding and watering steadily so flowering and fruiting continue; remove tired or diseased growth to keep energy going into new flowers.

For everything else this plant needs day to day, see the full watermelon care brief and its watering schedule — a stressed, badly watered plant rarely has the energy to flower at all.

Watermelon blooming — frequently asked questions

Why won't my watermelon flower?

Watermelon flowers (and then fruits) on the current season's growth — it needs full sun, warmth, steady moisture and a switch to a lower-nitrogen, higher-potassium feed once it starts to flower. The most common reason it is not happening: Too little sun — most of these need full sun (or very bright light) to flower well; shade gives leaves, not blooms.

How do I make watermelon bloom?

Give watermelon the sunniest spot you have — for most bedding and fruiting plants, more direct light directly means more flowers. Move off high-nitrogen feeds and use a higher-potassium "bloom" or tomato-type feed as it comes into flower.

When does watermelon normally bloom?