Seedless Watermelon Spacing and Pollenizer Placement

March 8, 2013 in Uncategorized

Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu

We have received several questions about seedless watermelon spacing and pollinizer spacing as growers make final decisions for 2013. Several growers had questions about 2 ft versus 3 ft in-row spacing as well as pollinizer placement.

The original work on seedless watermelons when spacing recommendations were developed showed no difference in yield or returns between 2 ft and 3 ft in-row spacing with standard size (14-24 lb) seedless watermelons. Wider spacing (4 ft or greater) reduced yield, closer spacing (2 ft, 1 ft) did not yield better than 3 ft between plants.

Another common question is, will changing in-row spacing affect fruit size in seedless melons? Some studies have shown that decreasing in-row distance decreased number of fruit per plant but did not decrease fruit size. Other studies have shown that if square footage per plant is maintained, closer in-row spacing will increase the number of smaller melons but not affect overall tonnage. This effect will be variety dependent. In our research in 2012 in comparing 3 ft and 4 ft spacing, overall yields in the variety Fascination were not affected; however, in the variety SS 7187, yields were decreased at the 4 ft spacing. Fruit sizes for both varieties increased significantly from 3 ft to 4 ft spacing.

Our recommendations for standard size watermelons are 20-25 square feet per plant. On 8 ft bed centers this would be 2.5-3 ft between plants. On 7 ft bed centers this would 3-3.5 ft between plants. This maximizes yield with the minimal plant cost.

In mini-watermelons (under 8 lbs), the standard recommendation hast been to plant at a 2 ft spacing between plants. However, recent research has shown that yield and size grades were optimized at a 1 ft in-row spacing.

The definitive work with pollenizers showed that pollenizers between every third and fourth seedless plant (seedless planted every 3 ft) optimized yields when compared to dedicated rows or pollenizers planted every fourth plant.

Our research has shown that the majority of special pollenizers performed well in this configuration (seedless at 3 ft, pollenizers between seedless plants 3 and 4). However, most standard seeded types when used as in-row pollenizers were too competitive and reduced yields. An exception was with the standard seeded type ‘Stargazer’ which performed equal to the special pollenizers. In research in the south, they have shown similar results using the seeded variety ‘Mickylee’ as an in-row pollinizer.

A recent inquiry was the potential for planting every 2 ft with a standard diploid pollenizer every fourth plant. This system should perform equal to our standard (seedless at 3 ft., pollinizer between plants 3 and 4). However, plant cost will be higher.