Squash cross pollination seed saving

So for saving seed, we do not want cross pollination. On squash, these winter and summer, which of these varieties will be safe to plant together and not contaminate each others seeds?
*BUTTERNUT SQUASH (Cucurbita moschata)
*Pennsylvania Dutch Winter Neck Squash (Cucurbita moschata)
*Triamble (Cucurbita maxima)
*Tarahumara Indian winter squash (Cucurbita pepo L.)
*Queensland Blue Winter Squash (Cucurbita maxima)
*Summer yellow squash (Cucurbita pepo)
*Cinderella Pumpkin(ROUGE VIF D’ETAMPES) (Cucurbita maxima?)
Which are safe to plant together and not cross the seeds?
Are Tarahumera Indian winter squash and summer yellow crookneck really both pepo? They look very different by appearance. Do they cross?

If it is Pepo, it will readily cross with a Pepo. If a Maxima, it can be crossed easily with a Maxima.

To prevent cross pollination just plant one variety of each of these.

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If you only need seeds from one pumpkin or so, I would plant them all together and hand pollinate. Go out the night before you want to pollinate and pick your female flower and a male flower or so from the same plant. Either put a small cup over the flower or tie it closed with a zip tie or piece of string. This makes sure the flowers don’t open and bees visit them.

Go out early in the morning and cut off the male flowers and pull off all of the petals exposing the stamen. Now pollinate the female flower with the male flower and tie the female flower closed again. I would remove the tie the next day. You will have to keep this pumpkin marked so you keep the seeds from that exact pumpkin, but no need to limit what you grow.

Giant pumpkin growers do this so they know the lineage of their seeds. You can find Youtube videos on hand pollinating giant pumpkins, which might help.


I should be more specific, the flower is only really open for one day. So the night before you pick flowers that look like they will open the next day. That’s when you tie or cover them.

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I have been growing and saving seed of the same butternut squash for several decades.
They originally were of the tipical shape , as the one on the right.
Then I noticed some with longer necks ,with more percentage of the meaty part, smaller seed cavity’s.
Saving seed from these , has given me a strain with much longer meaty necks, as per the 3 on the left.
No controlled crosses, just saving seed from the meatiest ones.


Those are some nice looking neck pumpkins!

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Paul, I suggest Suzanne Ashworth’s “Seed to Seed”, an excellent resource for seeed savers. Well written, very good explanations and instructions. Squahes can be a lot of fun once you understand the families and possible crossing. Sue


The worst cross would be summer and winter squash.
Most summer squash, Acorns, and Pumpkins are Curcurbita pepo, so keep them away from the Delicata and any Moschata type.
Maxima and Moschata squash hybridize.
Do you have a long, “over 120 day” growing season?

Unfortunately for me
It’s not warm enough to grow Butternut squash locally.
The plants grow
But rarely get fully mature.