What is the proper method of growing summer/winter squash from seed?

Asked January 4, 2015, 8:41 PM EST

I would like your opinion on the proper method of growing summer/winter squash from seed. I've seen multiple different recommendations. Some say plant 3 seeds and then thin to one plant. Other places say plant 4-5 seeds and thin down to 2-3 plants. I've seen different recommendations for the same variety being sold by different seed vendors. The instructions from one vendor says thin down to 1 plant...the instructions from another vendor says thin down to 3 plants. For someone with limited garden space, I would obviously prefer to thin down to 3 plants. Is there an advantage/disadvantage to either method?

Washington County Oregon

1 Response

Thank you very much for your thought-provoking question.

Let's break down the question with a few more questions.

How old is your seed? Germination rates decline with seed age. If your seed is held over from last year and stored in the kitchen cabinet or is more than three years old, an additional one or two seeds may be called for in order to get one plant. Germination can be helped by holding the seeds in a dry , cool place during storage, such as a zipper closure food bag in the back of the refrigerator or a cool dry cabinet in a basement. Fresh seed should have a germination rate on the packaging or in the seed catalog.

How much room do you have? What is the habit of the plant? Bush varieties can be 3-4 feet across and require plenty of space to aid in air circulation to avoid mildew diseases. It is likely that you will only want 1 bush zucchini or Bush Delicata plant per hill. Vine varieties can grow together along the ground, but they can be up to 20' long. Vines can also be trellised, provided you have a sturdy structure.

How much squash do you want? If you are just growing for yourself and a small family, more than one prolific Zucchini plant can cause you to have to make a LOT of zucchini bread, as they do not store long and must be picked young for peak flavor and continued production. Pumpkins can pose a similar problem, as we typically have a short warm period between harvest time and our cold, wet Autumns. They require time to "cure" before they can be stored in the home. Please look at publication EC 1632-E at www.extension.oregonstate.edu/catalog for information on curing and
storage.

Another factor that is important to know is that squashes require soil fertility, 10+ hours of sun during growing season and calcium to produce fruit. If supplimenting the soil is difficult, or you have a less than optimally sunny spot, it is likely that one healthy plant is better than three poor ones.

There are advantages and disadvantages to each strategy in planting squash. As a person who has limited garden space, remember plant quality is important. Be sure that you have enough space for the plants you want, but don't be afraid to thin them out if it looks like more than one will be a burden.
I do hope that this has been helpful. Thank you very much for using Ask an Expert.