How to Grow Crocus for Saffron
As an Amazon Associate we earn from qualifying purchases.
How to grow crocus for saffron comes down to one fact: the spice is the red stigma inside a fall-blooming crocus flower, and each flower produces just three of them. The rest of the work is planting corms in well-drained, sunny soil, keeping them away from rodents and standing water, and picking flowers on the right morning.
This guide follows six extension and university pages. They agree on the main steps and disagree on several numbers, including planting depth, hardiness zone and drying temperature. Each disagreement is shown beside the page that gave it. The guide recommends no product.
Quick answer
- Plant corms in full sun and well-drained soil in late summer or early fall. The guides differ on the month, from August to October.
- Set the corms between 2 and 6 inches deep. The sources disagree, so take the figure from your regional extension page.
- Pick flowers in the morning, pull out the three stigmas, dry them, and wait a month before using them.
- Expect a small first crop. Penn State says a corm may give one flower in the first year and six to nine in years two and three.
What one gram takes
The yield math explains why saffron is expensive. UVM’s news article says it takes approximately 150 to 170 saffron flowers to produce one gram of spice. Penn State says each flower produces just three stigmas, which must be plucked by hand or with tweezers. That makes roughly 450 to 510 stigmas for one gram.
| Dried saffron | Flowers needed (150 to 170 per gram) | Stigmas needed (3 per flower) |
|---|---|---|
| 0.5 gram | 75 to 85 | 225 to 255 |
| 1 gram | 150 to 170 | 450 to 510 |
| 2 grams | 300 to 340 | 900 to 1,020 |
Illinois Extension arrives at a larger corm count. It says the stigmas lose about 80 percent of their weight as they dry, so a gardener would have to plant 150 corms to pick enough stigmas for one gram. Penn State says a corm may give only one flower in its first year and six to nine in years two and three, so a new bed yields far less than a gram in its first season.
Pick the site and the planting window
Saffron needs full sun and soil that drains. NC State lists full sun as six or more hours of direct sunlight a day, and Penn State asks for at least five hours of direct light. Penn State puts the drainage point plainly: “Corms will rot if the soil is too wet.” UVM adds that standing water or excessive moisture can rot the corms.
The soil targets differ. UVM describes a light to moderate texture with a high level of organic matter. NC State asks for moderate organic matter. Penn State gives a pH of 7.0 to 8.0 and calls the soil nutrient-rich. The sources we opened give no pH figure from UVM or NC State.
The planting window is the first place the pages differ. UVM’s planting sheet says corms should be planted as soon as possible in August or early September, and it warns that corms held until spring will sprout and then die. Penn State gives September through October, and Illinois gives September.
Buy plump corms from a reputable source. UVM’s news article advises discarding any that are shriveled or soft or that show signs of disease.
Containers and raised beds both work. UVM’s planting sheet says corms can go directly into the bed, into a raised bed or into containers. Penn State says a container should be at least 6 inches wide and 8 inches deep, and it lists milk crates lined with landscape fabric. For the volume question, see the guide on how much soil a raised bed garden needs, and for the mix, see raised bed soil mixes.
Set the depth and spacing
Depth is the biggest disagreement among the pages. The sources we opened do not explain the gap, so the regional extension guidance for your site should decide the depth.
| Source | Depth as written | Spacing as written |
|---|---|---|
| UVM planting sheet (September 2021) | Around 6 inches | Usually 3 to 4 inches apart, at 6 to 12 corms per square foot |
| UVM news article (November 2024) | About three inches deep in the fall | Not stated |
| NC State Plant Toolbox | 4 inches deep | 4 inches apart |
| Penn State Extension | 3 to 4 inches deep | 3 to 4 inches apart |
| Illinois Extension blog (September 2017) | Two to four inches deep | Four inches apart |
Spacing agrees more closely than depth does. UVM’s density of 6 to 12 corms per square foot means a 10-square-foot bed holds about 60 to 120 corms.
Protect the corms from rodents and wet soil
Animals are a real risk. UVM’s planting sheet warns that squirrels and voles may eat corms in a garden bed, and that deer feed on the leaves over winter and spring, so netting may be needed. NC State says squirrels, mice and other rodents may eat the corms. UVM’s news article describes hardware cloth laid over the corms as a way to deter squirrels, chipmunks, mice, voles and rabbits.
Mulch is where the pages disagree. UVM’s planting sheet describes the potting soil on top as a mulch that keeps weeds down and insulates the corms in winter. UVM’s news article says researchers discourage covering plants with mulch because it may attract rodents.
Water once, then let winter pass
Penn State says to water only once after planting. UVM’s planting sheet says that after planting outdoors, natural rainfall should be enough. The corms should begin to sprout in about 30 days, and flowers emerge soon after.
The leaves keep growing through winter and go dormant in June or July, according to UVM’s planting sheet. Its news article says no insulation is required. Hardiness figures differ, as the table shows.
| Source | Hardiness as written |
|---|---|
| UVM planting sheet (2021) | USDA zones 4 to 8 |
| UVM news article (2024) | Hardy to zone 6, and survives zones 5 and even 4 |
| NC State Plant Toolbox | USDA zones 5a to 8b |
| Penn State Extension | Thrives in USDA zones 6 through 9 |
| Illinois Extension blog (2017) | Zone-hardy to 6; Central Illinois is zone 5b, and microclimates matter |
Harvest the flowers in the morning
Harvest timing is the most important daily task. Penn State says to pick in the morning after the dew or frost dries but before the sun wilts the flowers, because flowers wilt after just one day. UVM’s harvest sheet says to pick flowers when they are fully elongated and just beginning to open, since flowers picked closed and short may not have fully developed stigmas.
Early in the season, UVM’s harvest sheet says flowers can be picked every other day. At the peak, pick daily and do not wait more than two or three days.
Cut each flower at the base with a thumbnail and index finger, and pick only clean, fresh flowers. UVM says, “The leaves should not be picked.” Those leaves keep growing through winter and contribute to next year’s corms. Place the flowers on a clean tray or in a wide basket, avoid piling them deeply, and separate the stigmas as soon after picking as possible. If you cannot process them at once, spread the flowers on a paper towel on a tray and refrigerate them, as UVM’s harvest sheet advises.
Dry and rest the stigmas
Drying methods differ by page, as the table shows. UVM’s planting sheet recommends an oven or dehydrator at about 200 degrees Fahrenheit until fully dry. Penn State lists a range of oven settings, from 130 to 210 degrees, and also describes air drying indoors on a dry paper towel for one to two days.
| Method | Source | Setting as written |
|---|---|---|
| Oven or dehydrator | UVM planting sheet | About 200 degrees Fahrenheit until fully dry |
| Oven, first setting | Penn State Extension | 130 degrees for 60 minutes |
| Oven, second setting | Penn State Extension | 170 degrees for 25 minutes |
| Oven, third setting | Penn State Extension | 210 degrees for 7 to 10 minutes |
| Air drying | Penn State Extension | Indoors on a dry paper towel for one to two days |
After drying, rest the saffron. UVM’s planting sheet says to wait one month before using newly harvested saffron, and Illinois says the dried stigmas sit in an airtight container for a month before the flavor develops. UVM says to store the threads in a glass or metal jar with a tight-fitting lid, in a dark, dry place.
Divide the corms every few years
The corms multiply. UVM’s news article says to dig them up after several years and separate the daughter corms to prevent overcrowding. Penn State says to divide every four to six years during dormancy in July or August and to replant right away.
Check the plant before you harvest
NC State’s plant page lists autumn crocus as a common name for the saffron crocus, and it says Crocus sativus is often confused with Colchicum autumnale. The sources we opened do not describe how to tell the two apart in the garden, so buy corms from a reputable source and check with your local extension office before harvesting.
Mistakes to avoid
- Holding corms until spring. UVM’s planting sheet says they will sprout and then die.
- Planting in soggy ground. Penn State and UVM both say standing water can rot the corms.
- Picking the leaves. UVM says they should not be picked, because they feed next year’s corms.
- Waiting too long to pick. Penn State says flowers wilt after just one day.
How we chose
This guide draws on six pages that the sources we opened on 2026-10-23 covered: three University of Vermont pages from 2021 and 2024, NC State Extension’s Plant Toolbox, a Penn State Extension article updated in August 2025, and an Illinois Extension blog from 2017. We kept advice that a page states in plain words, checked each quoted sentence against its page, and show each figure where the pages disagree. The Illinois post is older, so the guide uses its numbers only where no newer page gives one.
What we could not verify
The pages disagree on planting depth, planting month, hardiness zone, mulch and drying temperature, and this guide does not settle those points. The sources we opened also give no yield per corm for a specific climate.
What the sources do not say
The sources we opened do not explain why the depth figures differ, and they do not say which depth suits a raised bed as opposed to the ground. None gives a soil temperature for planting. They do not describe how to tell saffron crocus from autumn crocus in the bed beyond naming the confusion.
Frequently asked questions
How many corms make a gram of saffron?
The sources do not give one answer. UVM’s news article says about 150 to 170 flowers make one gram, and each flower has three stigmas. The Illinois blog says a gardener would have to plant 150 corms for one gram. A corm may give one flower in its first year, so a new bed will yield far less than a gram at first.
When is the best time to plant saffron corms?
UVM’s planting sheet says as soon as possible in August or early September. Check your local extension office for the window in your area, since the pages do not agree.
Will saffron survive winter outside?
It depends on the zone and the page. UVM’s news article says the crocus is hardy to zone 6 and survives zones 5 and even 4, and it says no insulation is required. Penn State lists zones 6 through 9, and NC State lists zones 5a through 8b.
When do the flowers appear?
UVM’s planting sheet says corms sprout in about 30 days and flowers emerge soon after. Penn State says the leaves emerge in a few weeks and flowers appear within six to eight weeks. Penn State also puts the bloom between late October and December, while UVM’s harvest sheet says the season usually lasts four to six weeks.
How are saffron stigmas dried?
UVM’s planting sheet puts drying at about 200 degrees Fahrenheit. Penn State lists oven settings from 130 to 210 degrees and describes air drying for one to two days. Store the dried threads in an airtight container out of sunlight.
Bottom line
Plant corms in well-drained, full-sun soil in late summer or early fall at the depth your regional extension office recommends. Pick the flowers in the morning, pull the three stigmas from each one, dry them, and wait a month before using them.
Sources
- University of Vermont, North American Center for Saffron Research and Development, “Saffron Production for Home Gardeners: Planting Depth and Density for Saffron Corms” (September 2021): https://www.uvm.edu/%7Esaffron/pages/factsheets/SaffronplantingforhomegardenersSept2021.pdf (opened 2026-10-23)
- University of Vermont Extension, “Saffron: World’s Most Expensive Spice” (November 14, 2024): https://www.uvm.edu/news/extension/saffron-worlds-most-expensive-spice (opened 2026-10-23)
- NC State Extension Plant Toolbox, “Saffron” (Crocus sativus): https://plants.ces.ncsu.edu/plants/crocus-sativus/common-name/saffron/ (opened 2026-10-23)
- University of Vermont, North American Center for Saffron Research and Development, “Harvesting Saffron Flowers” (August 2021): https://www.uvm.edu/~saffron/pages/factsheets/HarvestingSaffronAugust2021.pdf (opened 2026-10-23)
- Penn State Extension, “Saffron: A Tale of Red Gold and How to Produce Your Own” (updated August 24, 2025): https://extension.psu.edu/saffron-a-tale-of-red-gold-and-how-to-produce-your-own (opened 2026-10-23)
- University of Illinois Extension, “Should we grow saffron crocus in Illinois?” (Flowers, Fruits, and Frass, September 15, 2017): https://extension.illinois.edu/blogs/flowers-fruits-and-frass/2017-09-15-should-we-grow-saffron-crocus-illinois (opened 2026-10-23)
