Growing Watermelon

Cucurbitaceae c. lanatus : Cucurbitaceae / the gourd family

Jan F M A M J J A S O N Dec
                S S S S
T                   T T
                    P P

(Best months for growing Watermelon in New Zealand - cool/mountain regions)

  • S = Plant undercover in seed trays
  • T = Plant out (transplant) seedlings
  • P = Sow seed
  • Grow in seed trays, and plant out in 4-6 weeks. Sow seed at a depth approximately three times the diameter of the seed. Best planted at soil temperatures between 70°F and 95°F. (Show °C/cm)
  • Space plants: 24 - 30 inches apart
  • Harvest in 12-17 weeks.
  • Compatible with (can grow beside): Sweetcorn, Sunflowers
  • Avoid growing close to: Potatoes

Your comments and tips

06 Feb 19, Cherry (New Zealand - temperate climate)
If you pick a watermelon early and its greenish, is there any way to ripen it up without throwing out to the chickens
06 Feb 19, Mike (New Zealand - sub-tropical climate)
Read up about when to pick them.
13 Jan 19, Grahame B (Australia - tropical climate)
Water melons must have been invented for rank amateurs. I live in Coconut Grove, Darwin, NT and have zero gardening experience, but decided to plant some water melon seeds (in pots) at the end of October - build up time to our summer wet season. They germinated fast so out into the garden they went with a lot less ground preparation than there could have been. They grew, started producing flowers (male only for quite some time) so I kept watering them with the odd bit of general purpose soluble plant food. I haven't seen any diseases so they haven't been sprayed - apart from the termite man's overspray with he did my house's annual ant and spider treatment. Then, in early December, growth went up a few notches; I could see how far a vine had grown in a day. They started taking over the garden. Flowers appeared everywhere, as did tiny native bees to attend to pollination. Every few days a small watermelon appeared and quickly got bigger. At that point I sought some advice from a local garden shop on what I should be doing; they told me to keep watering and sold me some organic fertilizer pellets to feed them with. Now they've taken over the garden, have started climbing fences and keep on producing new melons. I'd never have imagined it could be that easy.
09 Dec 19, Linda (Australia - tropical climate)
Hi Grahame, can you tell me what type of seeds you used please where they from a packet or out of a fresh melon? Thanks
13 Jan 19, Mike (Australia - sub-tropical climate)
I have never been able to grow them. I really don't have the ground to do it. Watermelons like virgin soil. There is a lot of difference between a plant growing well and producing a good end crop. I have rock melons growing - huge - some would weigh 3-4 kg. First one I picked, tasteless - probably too much watering. Have cut back the watering. Over watering when the fruit has grown it's full size can make the melons split. Hope it keeps going well for you.
15 Jan 19, Mike (Australia - sub-tropical climate)
Rock melon weighed 4.55 kgs
15 Jan 19, Grahame B (Australia - temperate climate)
Climate must be a big factor with water melons, Mike. We'll never get an overnight low of less than 24C in summer, and rarely get one under 18C in what we call winter, so I'm going to try growing them all year round. Evidently Darwin soils are very poor because nutrients get leached from them by the heavy rain during the wet season so I'm learning how to counter that. Having never been a gardener, the water melon experience has spurred me into action and today I'll be planting some papaya and guavas. I don't think the traditional favourites like plums and peaches can be grown up here but I'm looking into it. I do remember a particular plum from my childhood (50+ years ago!) called a greengage; they were green when ripe, and sweet. Has anyone on here ever grown them?
16 Jan 19, Mike (Australia - sub-tropical climate)
They grow water melons here - Bundaberg - in the spring. Winter 10 to 24 degrees with some nights down to 3-4-5. Spring time it is warming to 16 to 30 and summer 20-24 to 30-34. Seedlings are started late winter and transplanted in Sept. They pick them from late Nov and can extend into Jan. We can buy them on the side of the road - 2 for $5 - weigh from 2-3 kgs to 8-10 kgs.
27 Dec 18, Leon Brand (Australia - sub-tropical climate)
We are in Brisbane. Our watermelons start well but when the fruit gets to about rockmelon size the ends (opposite to the stem) starts to go back and soft. Our soil ph seems ok (about 6.8 with a Bunnings ph probe). I heard the problem may be a lack of calcium? Shall I work lime into the soil before trying again? Thanks in advance. By the way, beetroot is doing very well in the same area as the watermelon, and a few months ago we had a good egg plant crop in a nearby bed.
05 Jan 19, Mike Logan (Australia - sub-tropical climate)
Try planting them earlier - late August.
Showing 141 - 150 of 350 comments

Is July too late to plant or transplant? Or should I wait for August. Wanted to get a plant or seeds as a late Father's day gift but thought I should ask. It can always get a birthday present in August

- NSyed

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This planting guide is a general reference intended for home gardeners. We recommend that you take into account your local conditions in making planting decisions. GardenGrow is not a farming or commercial advisory service. For specific advice, please contact your local plant suppliers, gardening groups, or agricultural department. The information on this site is presented in good faith, but we take no responsibility as to the accuracy of the information provided.
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