Pumpkins and squash can be preserved for later use by freezing, canning or drying. They should have a hard rind and stringless mature pulp. Small size pumpkins (sugar or pie varieties) make better products.
Freezing is the only safe method for preserving pumpkin and squash purees, butters and preserves.
- Select full-colored, firm and undamaged produce.
- Wash, cut into cooking-size sections and remove seeds.
- Cook until soft in boiling water, in steam, in a pressure cooker or in an oven.
- When soft, remove pulp from rind and mash.
- To cool, place pan containing pumpkin in cold water and stir occasionally.
- Pack into rigid containers leaving ½-inch headspace and freeze.
Freeze these items for up to 1 year. Frozen pumpkin or squash is great to use in pies, desserts and as a vegetable. Thaw pumpkin and squash in the refrigerator - not on the counter - before using.
The only safe instructions for home canning stingless pumpkin and winter squash are for cubed flesh in a pressure canner. Follow these safety precautions:
- Soup made with pumpkin, winter squash, broccoli, cauliflower cannot be safely home canned. Freeze instead.
- Mashed or pureed or stringy squash like spaghetti squash, cannot be safely home canned because it's too thick preventing adequate heat penetration to the center of the jar allowing harmful bacteria, like c. botulinum can survive.
- While it is true that previous USDA recommendations had directions for canning mashed winter squash, but USDA withdrew those recommendations after studies conducted at the University of Minnesota in the 1970's found too much variation in density among different batches of prepared pumpkin purees to give a single processing recommendation to cover the variation among products.
- University of Minnesota researchers also evaluated processing times and methods and released updated recommendations released in 1994. Be sure to look at the date of the resources and choose sources printed from 1994 and beyond. Earlier editions do not have current methods and processes. Using recipes from canning publications or cookbooks dated before 1994 will be under-processed (Zottola et. al, 1978).
Caution: do not mash or puree! The density of this product prevents adequate heat transfer to the center of the jar and may allow harmful bacteria to survive.
To can pumpkin or squash:
- Cut the flesh into 1-inch cubes.
- Boil the cubes in water for 2 minutes.
- Fill the jars with cubes and cooking liquid, leaving 1-inch of headspace.
- Pumpkin and squash are low-acid vegetables and must be pressure canned. Process the vegetables at:
- 11 pounds pressure in a dial gauge pressure canner.
- Or 15 pounds pressure in a weighted-gauge pressure canner.
- For either method, process pints for 55 minutes and quarts for 90 minutes.
To use canned pumpkin or squash, drain the jars, mash the cubes and re-heat.
- Wash, peel and remove fibers and seeds from pumpkin or squash flesh.
- Cut into small, thin strips, no more than 1 inch by 1/8 inch.
- Blanch strips over steam for 3 minutes. Drain and pat dry.
- Dry the strips in a dehydrator until brittle.
- To reconstitute, use 1 cup of dried food to 2 cups of water.
- Pre-soak for 1 hour and then boil until tender.
1 cup of dried pumpkin or squash is enough for one pie.
Use pumpkin or squash in pickled products such as salsas, chutneys and relishes, but treat these products as fresh foods and refrigerate them. They cannot be safely canned by either the boiling water or pressure canning methods.
Butters and preserves
Refrigerate or freeze pumpkin or squash butters and gelled preserves to ensure they will be safe to eat. Pumpkin or squash butters and gelled preserves cannot be safely home canned.
Pumpkin and squash are low-acid foods and require special attention to preparation and processing. Currently, the USDA does not have any tested recipes for safely canning pumpkin preserves (jams, jellies, conserves or pumpkin butter). Research done at the University of Missouri found pumpkin butter made of mashed or pureed pumpkin and with added sugar to vary widely in acidity levels from batch to batch using the same recipe, therefore USDA deemed pumpkin butters unsafe for home canning.
Canning Pumpkins and Winter Squash - Cubed, 2018. National Center for Home Food Preservation.
Home Preserving Pumpkins. 2015. National Center for Home Food Preservation.
Let's Preserve: Squash and Pumpkins. 2021. Penn State Extension.
Zottola, E. A., Wolf, I.D., Norsiden, K.L. and D.R. Thompson. 1978. Home canning of food: Evaluation of current recommended methods. Jn. of Food Science 43:1731.
Reviewed in 2021