Eyal Vardi, Ph.D

The watermelon (Citrullus lanatus) is native to the dry areas of tropical and sub-tropical Africa, south of the equator, therefore very demanding in terms of sunlight and temperature throughout the growing period. 

Sowing and germination
The most common reasons for poor germination are over-watering and low temperatures. The minimum temperature for germination is 15⁰c (optimal is 25⁰c). For seedless varieties, the requirements are even higher at 28⁰-32⁰c with relative humidity of between 95-100%. During the first week in the greenhouse, water only in order to keep the growing medium wet. 

Transplanting
For seedless, a pollenizer (seeded variety) must be present to achieve fruit set. A ratio of three triploids (seedless) plants to one diploid (seeded) plant is recommended. Choose a pollenizer with fruits that can be distinguished from the seedless fruits. It is important to choose a pollenizer cultivar that produces male flowers within the same time frame that the female flowers appear on the seedless plant. 

Plant development
The minimum temperature for growth is about 12⁰c-15⁰c, depending on the cultivar. Optimal temperature for vegetative development is between 15⁰-20⁰c at night and 25⁰-35⁰c during the day. 
A standard fertilization program per hectare is 120-180 Kg N, 150-200 Kg P2O5 and 150-220 Kg K2. For grafted watermelon, the fertilization of P2O5 & K2 is significantly less and must be adjusted according to local conditions. Watermelons grow best when soil pH is between 6-7. 
In order to achieve the optimal fruit setting, it is recommended that the plants reach the pollination period in not too vigorous a state (by avoiding too much water and fertilizer).  

Pollination and fruit development 
Bees are essential to achieve pollination. Normally, one hive per acre is recommended. In order not to interfere with the activity of the bees, spraying should be done only with bee-friendly chemicals. Optimal temperature for pollination and fruit setting is 20⁰-25⁰c; temperatures up to 35⁰c are acceptable. For best fruit quality, there is an advantage to good exposure to sunlight. Fruits reach full maturity 35-45 days after setting in optimal conditions (15⁰-20⁰c at night and 25⁰-35⁰c during the day).   

Disease control
Origene Seeds varieties have disease resistance to some pathogens.
Please see the catalog and find your own variety to protect your environment and soil.

Note: Origene Seeds offer you these recommendations for growing watermelons according to its knowledge and experience.  These suggestions are general in nature and they will need to be adapted to different specific growing conditions.    

*** Plant pathogen alert: Please >> Click Here << and see the CGMMV Brochure on the ASTA website.