Why Are My Watermelons So Small and Not Growing?

Watermelons Not Growing

Every now and again you’ll plant watermelons and yes you do get melon, but they’re squeamishly small and stunted.

There are a number of reasons watermelons fail to grow to their anticipated size and at times even fail to ripen at all.

Here we discuss a variety of factors causing small watermelons. We’ll discuss how to prevent stunting your watermelon growth so you can enjoy that sweet, summer treat.

Here’s 5 reasons your watermelons growth may be stunted:

  • Maturity and Melon Variety
  • Watermelon Transplant Damage
  • Pollination Factors
  • Environmental Factors
  • Plant Damage and Disease

5 Causes of Small Watermelons

1. Maturity and Melon Variety

The first and foremost factor to consider is did you wait long enough? Watermelons have differing maturity dates, anywhere from 70 – 130 days or more depending on the variety and environmental factors.

Check the seed packet for the maturity date.

The second factor to consider assuming they have reached their maturity as per the cultivar is how big the variety you planted is supposed to be. Are you sure you didn’t plant a personal or mini style watermelon?

2. Watermelon Transplant Damage

If you started your watermelons from transplants as opposed to direct seeding, there’s a possibility you damaged the roots when doing so.

Damaged roots can’t always take up sufficient nutrients to support the hefty growth rate of watermelons.

Deep cultivation too close to the plant can also cause root damage.

3. Pollination of Watermelons

A picture of a large watermelon with a hand holding two small watermelons in front of it. Text reads "small stunted watermelons - why? I planted watermelon and all I got were these scrawny little balls!

Pollination is needed to produce quality watermelons. If weather was poor at pollination time, chances are your vines did not get as much traffic from bees and butterflies as they should have.

Poorly pollinated plants will produce fewer watermelons, smaller melons, and substandard ones. Inter planting a diversity of plants that attract bees in the vicinity helps to attract pollinators and reduce the risk of inadequate pollination.

4. Environmental Factors


The primary reason for small melons is temperature. Watermelons thrive in the dog days of summer, they are heat lovers.

A minimum of 60 degrees, but preferably more than a tad higher is needed. Lower temperatures lead to slower plant growth and ultimately stunted melons that are usually substandard in other mannerisms as well.

The best day time temperatures for Watermelon is 80 to 90 degrees, night time no lower than 60 degrees F.


Who put the Water in the Watermelon ? You did – I hope. If you didn’t that’s another reason why your watermelons may be stunted and substandard.

Watermelons love the heat, this is true, but they also crave moisture. Watering is critical to producing quality watermelons. The key time to water is from the time the fruit begins to form until it is half-grown.

As harvest time approaches you need to cut back on the watering so the fruits can concentrate their sugars. Excessive watering too close to the harvesting of watermelon will reduce the sugar content and cause the fruit to have hollow centers.

Check the soil moisture daily or more in hot arid and dry weather and water as necessary. Always allow the top inch and a half of soil to dry between re-watering.

Watering early in the morning is best so leaves will be dry by sunset, this will help to curtail fungal diseases. Some organic mulch wouldn’t hurt either. just around the base.

5. Plant Damage and Disease



Aphids are a common culprit for smaller melons. Usually, in an aphid infestation, the fruit is also distorted and misshapen. [See: Aphid Control] Aphids also spread a disease known as Watermelon mosaic virus which also leads to stunted growth.


They are microscopic worms which that dwell in the soil and feed on the host plant roots preventing them from taking up the nutrients they need to grow. Beneficial nematodes added to the soil will help prevent another occurrence.

Related: Why is My Watermelon Splitting?