Planting, Growing, and Harvesting Watermelons
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Planting
When to Plant Watermelons
- In cool climates with short growing seasons, start seeds indoors 2 to 3 weeks before your last frost date. Plan to transplant seedlings into the garden about 2 weeks after that date or when the soil has warmed to at least 65°F (18°C).
- In warmer climates with long growing seasons, sow seeds directly outdoors 1 to 2 weeks after your last frost date, as long as the soil temperature has warmed to at least 65°F (18°C).
- Young watermelon plants can also be bought from nurseries. Plant these after there is no longer a chance of frost; they are very tender. Watch the local forecast and err on the side of caution! Consider laying black plastic over your planting area to warm the soil even more.
- Tip: Starting with young plants can result in an earlier harvest (usually up to 2 weeks earlier), so consider buying young plants, particularly if you live in a cooler climate.
Choosing and Preparing a Planting Site
- Amend soil with aged manure, seaweed, and/or compost before planting. Watermelons are heavy feeders, meaning they need soil that is fertile and has a high nutrient level. Learn more about soil amendments and preparing soil for planting.
- Watermelons do best in loamy, somewhat sandy, well-drained soil. They can struggle in soil that contains too much clay and doesn’t drain well.
- Watermelons prefer a soil pH between 6.0 and 7.5 (“slightly acidic to neutral”).
- Watermelons need A LOT of space—up to 20 square feet per plant. Their vines need room to sprawl, so plant them in a place where they won’t crowd out other crops.
- Growing the vines in raised rows, known as hills, ensures good drainage and will hold the sun’s heat longer.
- Plan to space the plants 2-3 feet apart in a 5-foot-wide hill.
- If you’re growing in traditional rows, space them at least 6 feet apart.
How to Plant Watermelons
- Sow seeds 1/2 to 1 inch deep outdoors or 1/4 to 1/2 inch deep in seed-starting pots indoors.
- Tip: To allow for more root growth, use larger starting pots than you would for most seeds. Also, consider using compostable pots that can be cut away or planted directly in the garden, as this will minimize the risk of damaging seedlings’ tender roots during transplanting.
- If direct seeding outdoors, sow 4 to 6 seeds per hill, eventually thinning to 2 to 3 seedlings.
Transplanting Seedlings
- Handle watermelon seedlings with extreme care when you transplant. Their roots are very fragile, so try not to disturb the soil when removing them from pots.
- After transplanting, cover the plants with row covers to keep pests at bay. Remember to remove the row covers when you see both male and female flowers on the vine, as pollinators will need to access the flowers.
- Find even more tips for planting melons in your home garden.
Growing
Watering Watermelons
- Watering is very important—from planting until fruit begins to form. While melon plants are growing, blooming, and setting fruit, they need 1 to 2 inches of water per week.
- Keep soil moist, but not waterlogged. Water at the vine’s base in the morning, and try to avoid wetting the leaves and avoid overhead watering. Reduce watering once fruit are growing. Dry weather produces the sweetest melon.
Fertilizing
- If you choose to fertilize (and many do), make sure it delivers more nitrogen than phosphorus and potassium, as this will encourage leaf and vine growth. However, after flowering begins, use a fertilizer with less nitrogen to instead encourage flowers and fruit. We like to use a seaweed-based fertilizer.
Flowering and Fruiting
- Vines produce male and female flowers separately on the same plant. They often begin producing male flowers several weeks before the females appear. Do not be concerned if the male flowers fall off. The female flowers (which have a swollen bulb at the base) will stay on the vine and bear fruit.
- Blossoms require pollination to set fruit, so be kind to the bees! Learn how to support pollinators in your garden.
- As the fruit is ripening, prevent rotting by gently lifting it and putting cardboard or straw between the fruit and the soil.
General Watermelon Care Tips
- Mulching with black plastic or straw around the plants will serve multiple purposes: it will warm the soil, hinder weed growth, and keep developing fruits off the soil.
- Pruning generally isn’t necessary for watermelon plants, but vine productivity may be improved if you do not allow lateral (side) vines to grow and stick to the main vine. When the plant is young, just cut off the end buds as they form (before the side shoots become vines). You can also pinch off some blossoms to focus the energy on fewer melons (though it’s challenging to kill off a potential fruit).
- ‘Sugar Baby’: 80 days to maturity. Produces 10-pound melons with bright red flesh. This variety of smaller fruit can be planted just 4 feet apart.
- ‘Sweet Beauty’: 80 days to maturity. A 2004 All-America Selection. Bears 6-pound, oblong melons with red flesh.
- ‘Golden Midget’: 70 days to maturity. Bears petite, yellow-skinned 3-pound melons with pink flesh. Good for Northern gardeners.
Catherine Boeckmann
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I planted Sugar Baby Watermelon. It's growing very good. They are solid green but I'm not sure when to pick it. They do sound hollow now. Please advise
Hi - what is the reason that my watermelon is white inside? It is not sweet and the seeds are white too. Not sure what type I got, I planted a seed from a store bought watermelon. The watermelons are oblong with stripes. I cut one off because it was getting rotten at the tip. It was about 3 lbs. I would appreciate your response. Thank you.
This does happen with watermelons. For whatever reason some rot like this. It would have never reached maturity. I usually cut those kind off. Wait till the melon is yellowish on the bottom side then it is ripe.
My watermelons are as big as a Granny Smith Apple
How much longer till mature?
Do you know what variety it is? Do you still have the seed packet? They have a wealth of information on them like how many days it takes for the fruit to mature. I'd say that unless you have grown a watermelon that is supposed to be that small, you need to wait a little longer before harvesting. See the tests for maturity listed in the watermelon article above to know when it is time to pick it.
The watermeons at the grocery store are most likely hybrids, which are a cross between two different varieties. When you plant a seed from a (non-sterile) hybrid, the resulting fruit may not come out exactly like the original fruit (may not "come true"). They might be like one parent plant, or something totally different. There are white-fleshed watermelons; perhaps a white-fleshed watermelon was an ancestor to the watermelon that you saved the seed from?
I planted some jublie watermelons about 2 year's ago and they would sound ripe when thumped cut it open and still be green. Waited till the vine started to discolor same thing still green even went as far as the vein being rotting off and still green. A old timer told me I messed up when I limed my garden area I don't know if he was correct or not but most old farmers had been there done that and hardly ever wrong. I just wanted to get everyones input. I ended up plowing them up and didn't mess with it the following year and had some volunteers start growing and ended up geting a few ripe one's.
Your old farmer friend might be right! Watermelons like soil a little on the acidic side, a pH of 6-6.8 at the highest down to 5 at the lowest. Test your soil before you add any more amendments. The leaves produce sugars that help your watermelons to ripen. If they are dying off prematurely due to disease or insects the fruit doesn't stand of chance of ripening. Nothing is more disappointing than cutting into a melon you have been growing for months only to find that it is not ripe! Some tests, other than the thump test (which I have never perfected) are:
The tendril closest to the fruit will turn brown.
The fruit will twist off easily from the stem.
The white spot on the bottom of the fruit will turn yellow.
The rind of the melon will be dull green.
The vine nearest the end of the fruit will be cracked and brown.
The fruit should smell sweet when sniffed.
They should have a slight give when squeezed.
Hi, we planted watermelons this year, and do have watermelons growing pretty well. the problem is I keep finding some of my melons with eaten spots out of them, thinking a rabbit! Any ideas to keep him from eating them without hurting the rabbit? Is is possible if the eaten part isn't all the way thru the fruit,am I able to save any ot those? Thank you
You can take a rag or towel and put ammonia on it or bar of soap and cut up in the garden area in multiple areas I have heard of hair working also heard of people peeing aroind the garden. Probley best thing is a couple a fake owels or something motion sensored. Fence works for smaller animals . But wont stop a deer they say to keep a deer out is to get a mesh like fenceing and fix it in a way laying flat about 1 to2 feet off the ground cause the deer has good height perception but have depth or width perception which ever way you look at in. | ----
