Saving Seeds Bulletin No. 3: Squashes and Pumpkins
CUCURBITACEAE- CUCURBITS
The Cucurbitaceae family is a large family of plants that include the commonly known genus’ Citrullus (watermelon and citron), Cucumis (muskmelon, cantaloupe, cucumber), Cucurbita (squash and pumpkin), and Lagenaria (gourd).
All Cucurbitaceae species have imperfect flowers, meaning they are single-sexed, and therefore require a pollinator to reproduce. The plants produce both male and female flowers on the same plant (monoecious), often times the male flowers opening first. The plants of this family are heavily visited by pollinators, and any plants within the same species can cross-pollinate to produce seed that will not come true. These plants produce seed in the same year as they are planted (annual), and therefore require careful isolation, as many gardeners grow these popular plants. The isolation distances for cucurbits are 1/2 mile without any mechanical isolation. (For isolation instructions, see Saving Seeds bulletin No. 9.)
A minimum of ten plants of each species should be grown for a healthy seed stock, however Cucurbitaceae can tolerate fewer plants without expressing depressed vigor in the progeny. As such, for the home gardener, seed swapping of the same variety with other gardeners will help maintain a healthy stock of seed.
The male flowers of Cucurbitaceae are attached to a simple stem. Inside the flower is the pollen-producing anther. The female flower is attached to a small round ovary; the immature fruit. Inside the female flower is the stigma. Pollen from the anther must be introduced to the stigma in order for the fruit to continue to develop. For the seed saver, this can be done with hand pollination and subsequent bagging to prevent additional pollination. (For pollination instructions see Saving Seeds bulletin No. 10)
Flowers of this family must be carefully monitored in order to prepare for pollination, with many variations in requirements between species (see Seed to Seed by Suzanne Ashworth for more detail), Hand-pollination should be done on the earlier forming flowers to guarantee enough time for the fruit to fully form. As such, the best conditions would allow for the seed to be harvested from fruit that is a few weeks past maturity.
To harvest seeds, the fruit is cut open, seeds and attached material are removed, and the seeds are then fermented, much as they are for tomato seeds. The fermented seeds are then rinsed and dried until seeds snap in half easily. Seeds should then be stored in a cool, dry place, and will remain viable for 6-7 years under ideal conditions.
When saving seeds from tomatoes, the seeds need to be allowed to ferment in order to remove the growth inhibitors present in the gel sack that surrounds the seeds. To do this, scrape the seeds out of very ripe tomatoes, then place in a glass jar with a little water. Stir the seeds vigorously, cover with a cheesecloth, and allow to ferment. Fermentation has occurred when bubbles start to rise from the mixture. Do not leave the seeds in the water mixture past this point or they may begin to germinate. To clean, scrape off any seeds, plant matter, or mold that has formed on the top of the jar, and then pour off remaining water. Next, rinse the seeds by adding more water, stirring vigorously, and pouring off any seeds that rise to the surface again. The viable seeds will sink to the bottom of the jar. The leftover seeds in the bottom are then poured into a very small mesh strainer, and dumped onto a plate to dry out of the sun. Seeds should be stirred daily to prevent mold and to encourage drying.
