Can I save zucchini seed?

Top tips for saving zucchini seeds

• allow fruit to fully mature on the vine until skin is hard
• cover male and female flowers with mesh bags and hand pollinate
• ferment the seed

The short answer to whether you can save zucchini seed is ‘yes’ but it is a complicated process to achieve seed that is both viable and true. Not for the faint hearted!

Zucchini (Cucurbita pepo) belongs to the gourd family (Cucurbitaceae). The gourd family has several genera of which one is squash (Cucurbita) and one of its species is C.pepo or zucchini. Others include C. maxima and C.moschata (types of squash or pumpkin). Knowing this is important because cultivars in the same species can cross-pollinate meaning you will not get seed true to the original plant while cultivars that are from different species cannot cross-pollinate and you will get seed true to the original plant.

Within C. Pepo, there are a number of members including cocozelle zucchini, crookneck squash, Jack o’Lantern pumpkin, spaghetti squash, black beauty zucchini and zucchini of other colours, all of which can cross so saving seed requires isolation from other varieties. Commercially this is done with netting and exclusion of insects. In the home garden it requires covering the flowers before they open and hand pollinating them. Usually very fine mesh bags are used that exclude insects. Once the flowers have been pollinated the female flower needs to be covered again. If you plan to repeat the process, remove the male flower completely and use another bagged one next time. This process will give you true seed but there’s more to it.

Saving zucchini seed is notoriously difficult. The zucchini needs to be left on the vine until it is overgrown and yellowed – really quite large – and until the stem is woody and dried. The skin needs to be so hard that you cannot mark it with your fingernail. At this stage, it needs to be harvested and placed in a cool, airy (but not damp) place for a couple of months while the seed further ripens. Then there is the problem of getting the seed out!

The easiest way does not work for Melbourne – that would be to leave the hardened zucchini on the vine until the first frost. However, by the time the first frost arrives, the seed would be germinating inside the zucchini.

The best method is to ferment the seed (wet method):

• cut (or saw) open the zucchini
• scoop out the seeds
• place seeds in a bowl and just cover with water for 1-2 days, leaving the bowl uncovered. The water will smell ‘off’ when fermentation has taken place
• add more water so that seeds that are not viable will float to the surface and pour this layer away
• remove the seeds and wash again to remove any fragments of flesh
• place on a screen in a single layer and dry in a warm, airy environment, moving seeds around every day or two until completely dried
• store them in seed packets

Seeds should look plump when they are fully dried. This process can be used for cucumber seeds too.

Reference: Heistinger, Andrea, The Manual of Seed Saving, 2013, Timber Press

Useful links

Growing curcurbits – cucumber, zucchini and pumpkin

Written by Robin Gale-Baker