A quick guide to harvesting and storing melons, squash, and pumpkins

UNIVERSITY OF MINNESOTA EXTENSION - www.extension.umn.edu

The tendril on this watermelon is beginning to dry up. It will be ready to pick soon.

Melons are one of the trickiest plants to grow, because the guidelines around harvest are confusing and often contradictory. Gardeners often struggle to pick melons at the right time, and find that they are either flavorless, or mushy and overripe.

This is a quick guide to harvesting ripe and delicious melons. It also covers squash and pumpkins, which are in the same family as melons, and seem to be ripening ahead of schedule this year. 

Some ripening basics

Fruit and vegetables are typically assigned to two categories that define their ripening behaviors: climacteric and non-climacteric. 

Fruits and vegetables that continue to ripen off the vine

These fruits and vegetables are referred to as “climacteric.” You can harvest these fruits and vegetables before they are fully ready, and they’ll continue to ripen on your kitchen counter. Common examples of climacteric fruit include apples, bananas, peaches and tomatoes. 

Fruits and vegetables that do not ripen after harvest

These fruits and vegetables are referred to as “non-climacteric.” Once removed, the sugar content will not increase, and so picking at exactly the right time is important for flavor. These fruits and vegetables can still go bad if left out, but they will not get sweeter. Examples include grapes, strawberries and watermelon. 

However, sometimes the lines between climacteric and non-climacteric are a bit blurry, and this is especially true in melons. Ripeness is determined by a variety of traits including sugar content, how easily the fruit detaches, ethylene production, and firmness of the skin. 

Watermelons

The yellow spot on the ground will become more pronounced as the watermelon ripens.

Watermelons all belong to the same species, Citrullus lanatus. They were likely domesticated in the area around Libya and Egypt. All watermelons are non-climacteric, meaning they should be left on the vine until they are fully ripe. Signs of ripeness include:

• The spot where the fruit touches the ground becomes more prominent and changes color (typically yellow). 
• The tendril closest to the fruit becomes brown and dries up.
• Ripe melons have a hollow, dull sound.
• The sheen of the rind tends to change slightly with maturity, but this is variety dependent. 
• Watermelons do not reach “full slip.” This is a term you might see in seed catalogs, which refers to the time when a melon can easily be slipped from the vine.

Watermelons are sensitive to ethylene, and so they should be stored separate from ethylene producing crops like tomatoes, bananas, apples, or cantaloupe in order to extend the shelf life. 

Melons

“Melon” is a vague word in English; many other languages have distinctly different terms for the fruit belonging to the species Cucumis melo subspecies melo, and for watermelon, bitter melon, and other related but distinct cucurbits. Melon in this article refers to the Cucumis melo subspecies melo, which contains hundreds of distinct cultivars including cantaloupe and honeydew. Melons originated in both Asia and Africa, with the oldest known melons dating back to China in 3000 BC, and lower Egypt in 3700 BC. 

There are both climacteric and non-climacteric varieties within this species. While this is not a comprehensive summary, these are my main takeaways for farmers: 

Cantaloupe

"Full slip" is the point where cantaloupes slip easily from the vine. This melon is not quite ready.

The primary varieties of cantaloupe-style melons often have netted rinds, but not always, and they vary from lobed to smooth. They all have a relatively high sugar content. 

• Cantaloupe style melons have been consistently bred over time to be fully climacteric, meaning they will continue to ripen off the vine. 
• They can be harvested at “full slip,” meaning they are ripe when they easily pull away from the vine.
• Sometimes it’s easy for melons to become over-ripe in gardens. Cantaloupe can reliably be harvested a little bit early (before “full slip”), and left to ripen on the kitchen counter. 

Honeydew group

Honeydew are the most well-known type of melon in the subspecies Cucumis melo spp. melo var indorus. This group also includes common melons like Piel de Sapo. These melons have an even higher sugar content than cantaloupe melons.

• These melons are, for the most part, non-climacteric. This means they will not continue to ripen or become sweeter after they are harvested.
• They will not reach “full slip”, so this should not be used as an indicator of ripeness. 
• Indications of ripeness vary across varieties, but common indications include rind color changes, and the presence of a sweet smell. 
• These melons should be fully ripe when you harvest them. 

Makuwa, Chinensis, and Conomon melons

(And other melons from China, Japan, Korea, and the Philippines)

This group is a bit less defined than the cantaloupe and honeydew groups, because there is more genetic variation between varieties. 

• They tend to range from non-climacteric to “weakly climacteric”, meaning they usually will not ripen or get sweeter once harvested.
• Since this group is variable, read the variety descriptions in your seed catalog, and check on these melons more often in storage. 

When reading variety descriptions, check for terms like “harvest at full slip,” “cut from vigorous vines when the skin begins to yellow,” and “cut from vines when the skin becomes soft.” 

All types of melons should be stored at 95% relative humidity. Cantaloupe should be stored at 40 degrees fahrenheit, and honeydew can be stored in slightly warmer conditions, between 45-50 degrees fahrenheit. The crisper drawer in a refrigerator is a great place to store these melons once they are ripe.

Winter squash and pumpkins

Winter squash that is ready to harvest - the vine has hardened and become woody, and the flesh doesn’t dent with pressure from a fingernail.

Winter squash and pumpkins fall into three main species groups: Cucurbita maxima  (kabocha, hubbard, arikara squash, some pumpkins)), Cucurbita moschata (butternut and some other winter squash), and Cucurbita pepo (pumpkins, zucchini, acorn, delicata, pattypan, and summer squash).

Pumpkins and squash originated across Mesoamerica, with specific types originating across the continents in places including Argentina, Brazil, Guatemala, Mexico, Puerto Rico, and the Southern United States.

All types of pumpkins and squash are non-climacteric, and so they should be allowed to ripen to full maturity on the vine. As pumpkins and squash ripen, the rind will become increasingly firm, and they should not dent when you press a fingernail into the skin. The vines usually also begin to decline when squash are ready, and the part of the vine immediately attached to the fruit (which will become the stem) should become hard and woody. 

Winter squash and pumpkins should be stored at 50% relative humidity, and around 50-55 degrees fahrenheit. They can last 1-6 months in storage, depending on the variety.

If left on your front porch, take them inside if a hard frost is projected. After sitting outdoors for a month or more, they should be eaten quickly, as outdoor conditions will decrease the shelf life.

Read more about Postharvest handling of fruit and vegetable crops in Minnesota.

This article was adapted from a more in-depth version for Fruit and Vegetable News. Avid gardeners who want to learn more can read the article here.