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How long to grow a watermelon depends on the variety and growing conditions, but most watermelons take between 70 and 100 days from planting to harvest.
If you’ve been asking yourself how long to grow a watermelon from seed, the answer is usually a bit longer than transplanting because seeds need extra time to germinate and establish.
Watermelons are warm-season fruits that thrive in full sun and well-drained soil, so the time it takes to grow them can vary based on your climate and how you care for them.
In this post, we’ll break down exactly how long to grow a watermelon, the factors that affect that timeline, and tips to speed things up so you can enjoy a sweet, juicy harvest sooner.
How Long to Grow a Watermelon: The Basic Timeline
How long to grow a watermelon is mostly determined by the type you plant.
Here’s a closer look at the typical timeline you can expect.
1. Days to Maturity by Variety
When figuring out how long to grow a watermelon, the first thing to check is the days to maturity on your seed packet.
Smaller varieties like Sugar Baby can take around 70 to 80 days, while larger ones like Charleston Gray may need 90 to 100 days.
Seedless watermelons often take a bit longer, sometimes up to 100 days, because they need specific pollination conditions.
2. Starting from Seed vs. Transplant
How long to grow a watermelon from seed is longer than starting with transplants.
Seeds typically germinate in 7 to 10 days, and then you add that time to the overall growing period.
Transplants give you a head start of about 3 to 4 weeks, which shortens how long to grow a watermelon overall.
3. Germination and Early Growth
The first stage of how long to grow a watermelon is germination, which takes about a week in warm soil.
After that, seedlings need another 2 to 3 weeks to develop strong roots and leaves before they start vining.
This early phase is critical, so keep the soil moist and warm to avoid delays.
Factors That Affect How Long to Grow a Watermelon
Several things can change how long to grow a watermelon, so let’s look at the biggest ones.
1. Temperature and Climate
Watermelons love heat, and how long to grow a watermelon is directly tied to temperature.
They grow best when daytime temperatures are between 70°F and 90°F.
If it’s too cold, growth slows down, and how long to grow a watermelon can stretch by weeks.
2. Sunlight Exposure
Full sun is essential, and how long to grow a watermelon depends on getting at least 8 to 10 hours of direct sunlight daily.
Shade or cloudy conditions can delay ripening and reduce fruit sweetness.
So the more sun, the shorter how long to grow a watermelon will be.
3. Soil and Watering
Well-drained, fertile soil helps speed up how long to grow a watermelon.
Watermelons need consistent moisture, especially during flowering and fruit development.
But overwatering can cause root problems, which extends how long to grow a watermelon and may even kill the plant.
4. Pollination
Good pollination is often overlooked when people ask how long to grow a watermelon.
Without bees or hand pollination, female flowers won’t set fruit, and you’ll wait longer for a harvest.
Planting flowers nearby can attract pollinators and shorten how long to grow a watermelon.
Tips to Shorten How Long to Grow a Watermelon
If you want to speed up how long to grow a watermelon, try these practical tips.
1. Start Seeds Indoors
Starting seeds indoors 3 to 4 weeks before the last frost can cut down how long to grow a watermelon.
Use peat pots or biodegradable containers so you can transplant without disturbing the roots.
2. Use Black Plastic Mulch
Black plastic mulch warms the soil and can reduce how long to grow a watermelon by a week or more.
It also keeps weeds down, so your plants get more nutrients and water.
3. Choose Early Varieties
If you have a short growing season, pick varieties with fewer days to maturity to shorten how long to grow a watermelon.
Look for ones labeled 70 to 80 days for the quickest harvest.
4. Water Deeply and Regularly
Consistent watering helps maintain steady growth, which affects how long to grow a watermelon.
Aim for about 1 to 2 inches of water per week, including rainfall.
5. Fertilize Wisely
A balanced fertilizer at planting and again when vines start running can speed up how long to grow a watermelon.
Avoid too much nitrogen, which promotes leaves over fruit and delays how long to grow a watermelon.
So, How Long to Grow a Watermelon?
How long to grow a watermelon typically ranges from 70 to 100 days, depending on variety, temperature, sunlight, and care.
Starting seeds indoors, using mulch, and choosing early varieties can all shorten how long to grow a watermelon.
With the right conditions and a little patience, you’ll be harvesting sweet, homegrown watermelons before you know it.