Temperature and time, and the one place the sources disagree

Temperature is the one variable the cellar sets for you. Salt, weight, and container you choose; the room you ferment in decides how fast the work proceeds and whether it proceeds at all. The published guidance for fermented cucumbers and for sauerkraut is built around two figures: a temperature window and a duration. This page states what those figures are, what the sources say happens outside them, and the one place where two sets of documents flatly disagree.

What the published windows are for cucumbers

For fermented dill pickles, four publications print the same pair of figures: the national guide, Oregon State's PNW 355, Clemson's HGIC 3380, and Penn State. All four are adapted from the same USDA cucumbers document, and all four agree. At 70 to 75 F, fermentation takes 3 to 4 weeks. At 55 to 65 F, it takes 5 to 6 weeks. Above 80 F is to be avoided.

The reason given for the upper limit is texture. PNW 355 states it directly: "Pickles will become too soft if temperatures are above 80°F during fermentation." The national guide's troubleshooting material goes further and lists "Cucumbers stored at too high a temperature during fermentation" among the published causes of soft or slimy pickles. A crock held too warm does not merely work faster; it produces a pickle the sources tell you to discard.

What the published windows are for sauerkraut

For cabbage, the same four publications print the same core figures. At 70 to 75 F, sauerkraut will be fully fermented in three to four weeks. At 60 to 65 F, the figure is 5 to 6 weeks; PNW 355 also prints a plain 60 F entry, stating that "fermentation may take five to six weeks." The duration stretches as the room cools, and it stops altogether below a stated floor: below 60 F, "kraut may not ferment," according to the national guide and Penn State.

The upper limit for cabbage is lower than the one for cucumbers. Above 75 F, "kraut may become soft," per the national guide and PNW 355. In other words, a cellar that suits a cucumber crock perfectly can already be too warm for a cabbage crock sitting beside it.

A cold room stretches the calendar but does not break it

The pattern across both vegetables is the same in direction. Every published window that steps down in temperature steps up in duration by roughly the same amount: 3 to 4 weeks at the warmer setting becomes 5 to 6 weeks at the cooler one. The sources do not publish a curve, an acidification rate, or a pH measured against temperature; nothing of that kind appears in any accepted document, so nothing of that kind can be restated here. What the documents give you is pairs of figures, a stated floor below which fermentation may simply stop, and a stated ceiling above which texture fails. Between the floor and the ceiling, the instruction is patience: check the crock several times a week, remove scum or surface mold immediately, and let the cooler room take its longer time.

Where the sources disagree on sauerkraut

One accepted publication breaks rank. Colorado State's sauerkraut sheet, revised October 2025, directs fermentation at 68 to 72 degrees F for about 7 to 14 days. Every other document on this page prints 70 to 75 F with a duration of three to four weeks.

The disagreement is not small. Colorado State's recommended range overlaps the zone the other sources place below their optimum, and its stated duration is two to four times shorter than the three-to-four-week figure printed by the national guide, Oregon State's PNW 355, Clemson, and Penn State. If you ferment cabbage for 7 days at 70 F because one sheet says that is enough, you have a jar the other four documents would call barely half finished. If you ferment for four weeks on the authority of the four, you are two to four times past the other sheet's mark.

Neither side cites the other. This manual does not referee between them, because no accepted source does. Both figures are reported above exactly as printed, and the choice of which to follow belongs to you.

The disagreement applies to cabbage only

The cucumbers figures carry no such conflict. The national guide, Oregon State's PNW 355, Clemson's HGIC 3380, and Penn State all print identical windows and identical durations, all descending from the same USDA cucumbers document. If you are fermenting dill pickles, you may treat the table above as settled. If you are fermenting cabbage, you must know that two published answers exist and that no document reconciles them.

What marks the end, when the calendar is only a guide

No accepted source publishes a target pH or a reached pH for a home fermentation. There is no number to test against, no strip to read, no threshold that closes the process. The only published test of doneness is sensory: taste, and for sauerkraut weighted with a brine-filled bag, the cessation of bubbling. PNW 355 instructs you not to disturb the jar until fermentation stops, defined as when bubbling ends. Beyond that, the documents tell you to taste the product and to judge the flavor. The printed weeks are the range within which that tasting happens, not a substitute for it.

What this page does not tell you

This page does not give salt quantities, container sizing, weighting methods, or canning processes for either vegetable; those are the business of the recipe pages, which the site lists elsewhere. It also does not give any pH figure, any acidification curve, or any rate of souring as a function of temperature, for the reason stated above: none is published in any accepted source. And it does not resolve the sauerkraut contradiction between Colorado State and the four other documents, because no publication has done so. You are left holding both figures, printed as issued.

Sources of the figures on this page

• National Center for Home Food Preservation, University of Georgia, Dill Pickles, in the fermenting recipes, adapted from the USDA Complete Guide to Home Canning, AIB 539, revised 2015. Quantities, container, weight, fermentation temperature and duration, storage and the boiling water schedule for fermented cucumbers.
• National Center for Home Food Preservation, University of Georgia, Sauerkraut, adapted from the USDA Complete Guide to Home Canning, revised 2015. The 25 lb to three quarter cup ratio, the depth of the container, the fermentation temperatures and both processing schedules.
• Colorado State University Extension and FoodSmart Colorado, Understanding and Making Sauerkraut, reviewed October 2025. The only salt figure published as a percentage by weight, 2 to 2.5 percent, and a fermentation window of 68 to 72 F for 7 to 14 days.
• Oregon State University Extension Service, Pickling Vegetables, PNW 355, by Jeanne Brandt, revised July 2019, reviewed 2024. Equipment, water, salt and vinegar, the fermentation procedures and seventeen tested recipes.
• Penn State Extension, Let us Preserve: Fermentation, Sauerkraut and Pickles, updated May 22, 2023. Ratios, containers, temperatures, the prohibition on changing proportions, and the criteria for discarding a batch.
• U.S. Food and Drug Administration, Fish and Fishery Products Hazards and Controls Guidance, chapter 13 and appendix 4, fourth edition, June 2022. The limiting conditions for pathogen growth: minimum pH, minimum water activity, maximum water phase salt and minimum temperature, organism by organism.