Plants
Forsythia planting zones
Forsythia covers 4a–8b, but the zone is only half the answer. All 3 types below carry their flower display through the spring freeze window, so the date that window closes in your zone decides whether a late freeze costs you a season of flowers.
Published October 30, 2026 · Cite this page
The types
Which forsythia you are choosing between
| Type | Zones | A late freeze |
|---|---|---|
| Border forsythia Forsythia × intermedia (e.g. ‘Lynwood’, ‘Spring Glory’, ‘Beatrix Farrand’) | 5a to 8b, then too little winter to flower | Exposed 8 to 10 feet tall and 10 to 12 wide (NC State, Clemson); Iowa State says the flower buds of ‘Lynwood Gold’ and ‘Spring Glory’ are not reliably hardy there. |
| Bud-hardy northern forsythia Forsythia ‘Meadowlark’, ‘Northern Gold’, ‘Northern Sun’ | 4a to 8a, then too little winter to flower | Exposed Selected for flower bud hardiness (Minnesota, Illinois); ‘Northern Sun’ is hardy to zone 4 (Clemson). |
| Dwarf forsythia Forsythia Gold Cluster, Show Off Starlet, ‘Fiesta’ | 4a to 8a, then too little winter to flower | Exposed 3 to 6 feet, for small spaces; on Minnesota’s list for cold climates. |
Zone ranges and bloom habit are a judgement — horticultural convention, not a measurement, and the same standing as the heat ratings on our crop tables. Everything below this panel is measured.
Zone by zone
Which forsythias are hardy where, and when the freeze lands
The two left columns come from the variety table above — a judgement. The two right columns are measured: they are the median last spring freeze across every NOAA station the zone’s ZIP codes actually cite, and how much later the one-year-in-ten freeze arrives.
| Zone | Hardy here | Flowers exposed | Last spring freeze | 1 year in 10 |
|---|---|---|---|---|
| 4a | 2 of 3 | 2 | May 6 – May 27 across 298 stations | about 14 days later |
| 4b | 2 of 3 | 2 | May 2 – June 1 across 477 stations | about 14 days later |
| 5a | 3 of 3 | 3 | April 28 – May 31 across 718 stations | about 14 days later |
| 5b | 3 of 3 | 3 | April 22 – May 28 across 752 stations | about 15 days later |
| 6a | 3 of 3 | 3 | April 18 – May 24 across 1004 stations | about 16 days later |
| 6b | 3 of 3 | 3 | April 11 – May 19 across 991 stations | about 16 days later |
| 7a | 3 of 3 | 3 | April 5 – May 9 across 941 stations | about 17 days later |
| 7b | 3 of 3 | 3 | March 30 – April 26 across 679 stations | about 16 days later |
| 8a | 3 of 3 | 3 | March 20 – April 16 across 689 stations | about 17 days later |
| 8b | 1 of 3 | 1 | March 7 – April 17 across 700 stations | about 19 days later |
“Hardy here” and “flowers exposed” are a judgement, from the variety table above. The freeze dates are measured — NOAA 1991–2020 climate normals, and the range is across the stations the zone’s own ZIP codes cite rather than one station chosen to speak for it.
Why the date matters
Your zone does not tell you your last freeze
Across the 10 zones above that publish a range, the median last spring freeze varies by 34 days inside a single zone — 21 days even in the tightest, zone 4a, and 41 in the widest, zone 8b. Two gardens with the same zone on the label can be a month apart on the date that decides whether forsythias flower.
And the median is not the risk. Across the 5,673 NOAA stations serving these zones, the freeze that arrives one year in ten lands a median of 16 days after the median date, and 20 days after it at the tenth of stations where that tail runs longest. A variety marked exposed above has its flowers standing in front of that whole window, not in front of one date.
⛔ We publish no temperature at which a bud is lost. NOAA’s normals give dates, not damage thresholds, and inventing a number to bridge the two is the one thing this site refuses everywhere else. What is on this page is when the freeze arrives and which flowers are out when it does.
Which forsythia for your zone
NC State Extension’s plant toolbox rates border forsythia for zones 5a to 8b, and Clemson says it is adapted to all of South Carolina. In the North the limit is the flower buds, not the plant: University of Minnesota Extension says the dormant flower buds of non-hardy varieties are often winter-killed there, so they bloom only near the ground, where snow covered the buds.
| Forsythia | Notes | Source |
|---|---|---|
| ‘Meadowlark’, ‘Northern Gold’, ‘Northern Sun’ | Selected for flower bud hardiness; ‘Northern Sun’ is hardy to zone 4 | Minnesota, Illinois, Clemson |
| ‘Fiesta’, Gold Cluster, Show Off Starlet | Compact, 3 to 6 feet; recommended for Minnesota | Minnesota |
| ‘Lynwood Gold’, ‘Spring Glory’ | Flower buds not reliably hardy in Iowa | Iowa State |
| ‘Beatrix Farrand’, ‘Karl Sax’, ‘Spectabilis’ | Large border forsythias; ‘Karl Sax’ blooms about 2 weeks later | Clemson |
Minnesota says even the hardiest forsythia can lose flower buds in mid- or late-winter thaws. Forsythia flowers before its leaves, in late February or March in South Carolina (Clemson) and April or early May in Minnesota, so in most zones it is in bloom inside the last-freeze window in the table above.
Planting and soil
- Full sun for the most flowers (Clemson, NC State); Illinois says the less light forsythia gets, the fewer blooms.
- Almost any soil that drains. Minnesota gives pH 5.0 to 8.0 and suggests a soil test; NC State says it tolerates poor soils, salt, drought and city conditions.
- Room to grow: 8 to 10 feet tall and 10 to 12 wide (NC State, Clemson). Clemson says forsythias do not belong where they must be kept in bounds, such as foundation plantings, unless you choose a compact cultivar.
- For a hedge, Clemson plants 3 to 4 feet apart.
Pruning: right after bloom
Forsythia flowers on last year’s wood. Iowa State says the buds begin to form by early summer, and that pruning any time from midsummer until just before bloom drastically reduces flowering; NC State says pruning after mid-July likely removes next spring’s buds. All the sources prune right after it blooms.
- Thin, do not shear: Clemson removes the older branches at the base and lets the vigorous ones take over. Illinois takes out a quarter to a third of the oldest stems at ground level every other year.
- Rejuvenate an overgrown plant by cutting it back to within a few inches of the ground in winter; Illinois says it may then take a year or two to bloom.
- Shearing into a box hedge, Illinois says, means pruning later in the season and cutting off flower buds.
Full guide: How to Prune Flowering Shrubs: Spring vs Summer Bloomers
Supplies
Supplies the sources mention
Each link opens an Amazon search for a plain kind of product, not one we picked. We have not tested these, and we do not rank them.
As an Amazon Associate I earn from qualifying purchases. It costs you nothing extra and changes nothing on this page: the dates are NOAA’s and the advice is the extension services’. Affiliate disclosure
- LoppersIllinois Extension takes a quarter to a third of the oldest forsythia stems out at ground level every other year.
- Bypass hand prunersClemson thins forsythia rather than shearing it, cutting the older branches at the base.
- Pruning sawIllinois cuts an overgrown forsythia back to within a few inches of the ground in winter to rejuvenate it.
Why forsythia does not bloom
Illinois Extension and Iowa State give three reasons: it was pruned at the wrong time, from fall through winter or from midsummer on, and the buds were cut off; it gets too little sun; or winter killed the flower buds, which are less hardy than the plant. Flowers only below the snow line are the sign of the third (Minnesota).
Forcing branches indoors
Clemson cuts branches between early January and late February, brings them indoors and stands them in water; the flowers open in about 10 days.
Common problems
- Phytophthora root rot in poorly drained soil, the most common problem in South Carolina (Clemson).
- Botryosphaeria canker on drought-stressed plants, and Phomopsis gall, round knots along the branches; Clemson prunes out affected branches and disposes of them.
- Leaf spot, crown gall and dieback, and spider mites, aphids and four-lined plant bug (NC State).
- Deer occasionally, and suckers (NC State).
Illinois suggests spicebush as a native alternative with yellow spring flowers.
Common mistakes
- Pruning in fall or winter, which cuts off the flower buds (Illinois, Iowa State).
- Shearing into a box. Clemson thins old branches at the base instead.
- A non-hardy cultivar in the North; Minnesota says its flower buds are often winter-killed.
- Shade. Illinois says the less light, the fewer flowers.
- A full-size forsythia in a foundation planting (Clemson).
- Poorly drained soil, which invites root rot (Clemson).
We found no Texas A&M or UF/IFAS source on forsythia we could read; the Southern advice here is Clemson’s and NC State’s, and NC State rates border forsythia only to zone 8b.
Your ZIP code
Your ZIP, your answer
Enter your ZIP code to see your USDA zone, which of the 3 types on this page are rated for that zone and when its late-freeze window runs, read from the table on this page, and the freeze dates of the NOAA station nearest you.
Your answer appears here.
Full details for any ZIP code: ZIP code zone finder.
Questions
- What zones does forsythia grow in?
- NC State Extension rates border forsythia for zones 5a to 8b, and Clemson says the cultivar ‘Northern Sun’ is hardy to zone 4.
- When should I prune forsythia?
- Immediately after it flowers in spring. Iowa State says the flower buds begin forming by early summer, so pruning from midsummer until bloom drastically reduces flowering.
- Why does my forsythia only bloom at the bottom?
- Winter killed the flower buds above the snow line. University of Minnesota Extension says that is the sign of a variety whose flower buds are not hardy enough, and suggests bud-hardy cultivars such as ‘Meadowlark’ and ‘Northern Gold’.
- Can I cut forsythia to the ground?
- Yes, to rejuvenate an overgrown plant. Illinois Extension cuts it back to within a few inches of the ground in winter, and says it may take a year or two to bloom again.
- How do I force forsythia branches to bloom indoors?
- Clemson cuts branches between early January and late February and stands them in water indoors; the flowers open in about 10 days.
Sources
Freeze dates on this page are NOAA 1991–2020 Climate Normals, for every station the ZIP codes in each zone cite. Zones are the USDA Plant Hardiness Zone Map, 2023. The type table is a judgement, as labelled above. Growing advice is quoted from the extension publications below, each written for its own area.
- NC State Extension Gardener Plant Toolbox, Forsythia × intermedia (border forsythia) . Written for: North Carolina (USDA zones 6b–9a).
- Clemson Cooperative Extension, Home & Garden Information Center, Forsythia (HGIC 1064) (Updated November 27, 2018). Written for: South Carolina (USDA zones 8a–9b).
- University of Minnesota Extension, Forsythia . Written for: Minnesota (USDA zones 3a–5a).
- University of Illinois Extension, Help! My forsythia isn’t blooming like it used to , by Ken Johnson (March 28, 2025). Written for: Illinois (USDA zones 5a–7a).
- Iowa State University Extension and Outreach, My forsythia shrubs are vigorous and healthy, but don’t bloom well. Why? . Written for: Iowa (USDA zones 4b–6a).
- Penn State Extension, Pruning Flowering Shrubs , by Sandy Feather (Updated July 10, 2025). Written for: Pennsylvania (USDA zones 5b–8a).
Published October 30, 2026
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- All plant guides
- When to Plant Trees and Shrubs in Fall, by Zone — watering and mulch after planting, and the last fall planting date for each zone
- ZIP code zone finder — your exact USDA zone, and your nearest NOAA station’s freeze dates
- What survives my winter — the same zone arithmetic over 74 perennial edibles, which is a separate table from the one above
- When to start my seeds — the spring calendar anchored on the same measured last-freeze dates
- Your hardiness zone is not a planting date — the whole dataset behind the spread quoted above