I have been growing melons on a small but professional scale for a good 4 years now. In the process, I have learned a few things about growing melons that I wish I had known earlier. Over the years I have researched more and more facts, but I have also learned a few things the hard way. I am happy to share this knowledge with you so that you can grow melons successfully in your own garden!
A central question that you ask yourself when planting vegetables is when they will ripen. I wanted to know how long it takes until I can harvest the first fruits, or how many fruits I can expect.
I decided to look at two varieties of muskmelon in a more scientific way for the 2022 harvest season. A commercially available “Cézanne“, which can be bought in practically every garden store, and a somewhat special sugar melon called “Scarlet Lady F1” (Ogen-type). All plants were sown at the same time and planted in the unheated high tunnel on 20.04.2022. The following day, the melons were raised on strings. On 28.05.2022, the side shoots were pruned once. The plants were continuously tied up throughout the growing season. The first ripe fruits were harvested on 12.07.2022, around 83 days after planting and a good 102 days after sowing. The cultivation season ended on 06.08.2022 for “Cézanne” and around a week later on 14.08.2022 for “Scarlet Lady F1”. The plants were still bearing small fruits, so I waited to see if they would ripen, but on 24.09.2022 it was clear that they would hardly reach full maturity and no longer meet my requirements in terms of taste.
Almost each harvesting season shows the exactly same shaped yield-curve. The graphic for 2022 is shown below. The x-axis is the timeline and the y-axis shows the number of fruits that were harvested. It becomes clear that both varieties have three peaks in harvest. Why this is the case is explained in the journal “How to prune melons”. For a constant daily harvest, it is therefore imperative to grow staggered crops. I would recommend three sets, each one week apart in age, for unheated cultivation in a high tunnel. This should lead to an almost constant harvest in the number of fruits per day during the harvesting season.
How many fruits can you expect?
In this yield survey, 52 plants of “Cézanne” and 30 plants of “Scarlet Lady F1” were considered. With a total of 156 fruits of the variety “Cézanne” and 84 fruits of “Scarlet Lady F1” harvested when ready to eat, the average yield per plant was 3 fruits for “Cézanne” and 2.8 fruits for “Scarlet Lady F1“. My survey corresponds well with the data from various American vegetable producers and specialist agencies, with around 2 to 4 fruits per plant. Fortunately, this means that melons also thrive magnificently in protected cultivation in the somewhat harsher climate at the southern foot of the Jura.
Although many plants bore more than three fruits, in some cases over eight, barely half of them ripened. This is because the growing season is too short, even in the (unheated) high tunnel. From September onwards, the nights in my region become too cold for melons, so the plants stop growing. Various literature sources expressly point out that even in heated cultivation, no more than 4 fruits per plant should be allowed to ripen. Accordingly, fruits are broken out to better control the distribution of nutrients between the fruits and thus achieve maximum fruit quality. This is particularly important in outdoor cultivation, where a reduction of 2 fruits per plant is recommended. Sometimes the plants are topped, as excessive shading of the plants leads to poorer quality fruit.
Quickly read
- For cultivation in an unheated high tunnel, sowing/pre-cultivation is recommended towards the end of March; depending on the year, planting takes place around mid-April (until the end of May) after at least three true leaves have formed.
- For early-ripening varieties, the harvest begins at the beginning of July and lasts until around mid-August.
- In protected cultivation, an average of 3 fruits per plant can be expected, and in open fields with 2 fruits per plant
How do bad years look like?
Read more about why 2023 was a “bad melon year” and what yield can be expected such seasons.
Two varieties of sugar melons were examined more closely in 2023. A commercially available smooth “Cézanne” was considered, in addition to a “netted Charentais”. Both muskmelons were sown on April 1st and planted at the end of April. Around 76 days after planting on July 10th, or 83 days for the netted Charantais melons and thus a week later, on July 17th, the harvest of marketable fruit began. This year the harvest was limited to a few days and ended for both varieties on July 22nd. With an average yield of 1.3 fruits per plant, the harvest yield is significantly lower than in previous years, even 56% lower than in the cool and wet summer of 2021.
This can be explained by the large fluctuations in day and night temperatures. Although the plants were optimally pollinated, watered and cut, they showed physiological fruit damage typical of melons, which occurs under increased stress.
Melon plants prefer temperatures of 20-23°C during fertilization and 20-25°C when ripe. Melon plants thrive best in a very narrow temperature range. As soon as temperatures reach a low of 15 °C, the plants stop growing; depending on the literature, heat stress occurs above 30 °C. The plant stops growing or drops the fruits. I only observed such behavior at temperatures of 36°C and over a longer period of several hours. Since I cultivate melons without heating and cooling systems, climate control can only be carried out to a limited extent. Despite the high tunnel being open, it can briefly reach 48°C on sunny days! However, this was not a problem at times.
Although a number of heat records were set in Europe in 2023, it was anything but summery in my growing region. Not a single tropical night was recorded, and hardly any hot days. Throughout June and July the warmest night was 17°C in the high tunnel. The majority of the lowest temperatures were 12-13°C, and on July 22nd 2023 it was even 11°C.
The massive temperature fluctuations of up to 27 degrees Celsius prevented the formation of 3rd and 4th generation fruits. This clearly affected the average yield per plant.
After a brief trial in 2020, I did not pursue growing melons outdoors any further. Without intensive plant protection measures, melons are only suitable for outdoor cultivation to a limited extent in our harsh climate. Specially grafted melons on pumpkin rootstocks and Fusarium-resistant varieties are clearly preferable for outdoor cultivation. But still are no guarantee for any yield at all. What makes it even more difficult is that the snail problem in the field can only be dealt with with great effort. So not a single fruit was harvested for the year 2020.
I can therefore guarantee with great certainty that growing melons in Switzerland needs at least protection from above (roof) or below (ground cover) to ensure any yield at all.