Watermelons in the garden range from 1-8 per plant. Commercial watermelon grows often have tight spacing with high plant density that leads to 1-2 watermelons per plant. The main factors that decide how many watermelons one plant produces are plant spacing and watermelon variety.
Watermelons Per Plant – Watermelon Variety & Plant Spacing
Here’s a 2017 study by North Carolina State University on watermelon varieties. The watermelon per plant average for the 39 varieties grown was right around one watermelon per plant.
Because of tight spacing, commercial watermelon plants will produce 1-2 watermelons per plant. Some of the best producing cultivars include Bottle Rocket, Charismatic, Lemon Ice, Neptune, PeeDee Sweet, and Sugar Fresh.
As with most garden plants, hybrid varieties of watermelon usually have higher yields and are more disease resistant than heirloom varieties.
Plant Spacing vs. Yields In General
Plant spacing and yields have been studied thoroughly with corn because of the crops importance. Corn fields are spaced tight for optimal results leading to most corn stalks producing one good ear of corn per plant. However, it’s common for corn on the edge of fields to have multiple ears.
The extra space on the edge of the field gives the plants more access to water, nutrients, and sunlight that the plant uses to produce more ears. Corn spaced too tight will not grow ears at all. Watermelons are the same way.
Tighter spaced watermelon plants, up to a point (around 2 square feet), will yield more in overall weight but have less watermelons per plant.
Watermelon Yields Study – Variety, Black Plastic Mulch Use, Plant Spacing
In this study done by the Department of Horticulture of the University of North Carolina State University, two varieties were grown for three consecutive years.
Both varieties had the same environment and the variety “Royal Jubilee” had higher yields than “Prince Charles” all three years. The first year “Royal Jubilee” out performed “Prince Charles” by 21%, by 25% the second year, and 34% the third year.
Yields in the three years differed significantly with the best year having 2x the yield than the worst year. Plant spacing and the use of black plastic mulch was different each year.
Polyethelene mulch use increased yields at all plant spacings. Yields were best with spacing of 0.7-0.9 m^2 per plant or about 2.1-2.7 square feet per plant.
Tighter spacing of watermelons leads to higher yields by weight, up to a point. Less than 2 feet of spacing between watermelons seems to be too tight and lead to less yields.
This is in line with square foot gardening practices that suggest 2 square feet per watermelon plant.
To learn more about how plant spacing and watermelons check out “How Far Apart to Plant Watermelons?“.
How Do You Grow Bigger Watermelons
If your goal is to produce big watermelons the first priority is to select a variety of watermelons that is known for producing big watermelons and then take excellent care of the plants. Regular fertilizer application, keeping the plants stress free (water and heat stress).
Stress stunts plants and reduces optimal growth and yields. Check out the section on increasing watermelon yields below for tips on keeping watermelon plants growing well throughout their life cycle.
The three types of watermelons are personal, icebox, and picnic with picnic varieties of watermelon being the largest. The world record for biggest watermelon is 350 lbs. and was “Carolina Cross” variety.
Create World Record Size Watermelon
If you want to create the biggest watermelon possible prune the watermelon plant down to one watermelon on a single plant and give it plenty of space.
I think picking which watermelon to leave is guesswork. A tip to know is when a watermelon reaches golf ball size you can be sure it has been successfully pollinated.
Increase Watermelon Yields
Here are some things to do to increase you watermelon yields.
- Plant Spacing – This is essential for overall yields. A tight spacing of 2 square feet per watermelon plant is ideal. Choose “bush” type watermelons or varieties that produce small watermelons combined with a trellis. Train the main watermelon in a zig-zag or circular pattern and prune runners. When doing intensive gardening plants are competing for nutrients, water, and sunlight. Be sure to fertilizer regularly to keep up with the dense plant growth.
- Variety – The main factor in choosing variety is the size of watermelon you want to grow: personal, icebox, or picnic. After that choose a hybrid variety that is well known for being a heavy producer.
- Apply Fertilizer – Watermelons are heavy feeders and need regular fertilizer to be all they can be and produce at their best. Jack’s Classic is a good standard water soluble fertilizer and Organic Plant Magic is my favorite organic fertilizer followed by Garden-Tone.
- Water Correctly – Watermelons should be watered at least 1″ of water a week up until flowering and fruit production when they should be watered 2″ per week. When the majority of fruit has reached a mature size go back to 1″ of water a week. These measurements include rainfall so use a rain gauge or measured rain barrel to accurately measure rainfall. Water deeply and less often for best results. This allows water to reach deeper and the top couple inches to dry so the shallow roots are not constantly wet. Typically watering right after a light rain is a good idea. Sticking your hand in the dirt is often the best way to know if it’s time to water. If the dirt is still sufficiently moist 3-4 inches down hold off on watering. If it’s dry then water.
- Hand Pollinate – Hand pollinating is a great idea and the way to give every female flower the best shot at becoming a watermelon. Watermelons are insect pollinated and rates of pollination can be poor for a few reasons. If you’re growing in an area without much insect activity or if temperatures are too low or high or if there’s a lot of rainy days during the pollination period. These things can all lead to poor pollination rates and a bad season. Hand pollination is easily done by swirling a paint brush or this thing inside a male flower and then female flower.
- Temperature – If temperatures are below 60 degrees or above 90 degrees for more than a few days especially during flowering and fruiting the plant can fail to set fruit and yields can be lower. The more common problem during this time is a heat wave. More frequent watering and protecting plants from the sun during the hottest time of the day with bed sheets, umbrellas, or shade cloth is a good idea. Mulch helps to keep weeds down, keep soil temperatures more even and help the soil retain moisture on hot days.
How Many Watermelons Do Farmers Get Per Acre?
The United States, and other developed countries in Europe have the highest yields of watermelons per acre, and most other crops, because of access to fertilizer and farming equipment. An average for watermelons per acre in the US is about 45,000 lbs. per acre.
An article from 2007 expected watermelon yields in Georgia to be between 40,000-50,000 lbs. per acre and said this was a good but not great yield for Georgia watermelon farmers.
In Imperial County, California from 1997 to 2001 average watermelon yields per acre were 52,400 lbs. per acre. The scientific paper suggests that 70,000-100,000 lbs. are possible with ideal conditions.
Check out “How To Plant Watermelon Seeds” for the ins and outs of planting the seeds.
How Long Does a Watermelon Plant Produce For?
A watermelon plant will not keep producing. It will produce fruit and then die. Even in Florida where watermelons are harvested year round they have to be successively planted.
Watermelons are annuals with varieties that take an average of 90 days to produce mature fruit. Male flowers appear on the plant first and then female flowers a week or two later.
The ovary behind the female flower will turn into a golf ball size and at that size you know the fruit has been successfully pollinated and it will become a ripe watermelon in 30-35 days from there.
Please comment below with any thoughts or experiences you have with how many watermelons grow per plant or anything else watermelon related.