Unlikely — Zone Mismatch
string of pearls (zones 9-12) does not overlap with Delaware's zone range (7a-8a). Growing outdoors is unlikely without significant protection.
One zone short — what would close it
String Of Pearls is hardy to zone 9, and the warmest ground in Delaware is zone 8 — 1 zone short. Planted in open ground it will not survive a Delaware winter. To grow it here, grow string of pearls in a hoop house or unheated greenhouse — its modeled 1.5-zone lift covers this gap.
A hoop house or unheated greenhouse is the lift this needs. How a greenhouse changes what you can grow →
Zone math from 9-12 (plant) against 7-8 (Delaware). Lift modeled by crop_engine.GREENHOUSE_ZONE_MODIFIER_BY_SUBTYPE['hoop_house'] (+1.5 zones) via api/fast_sections.py Unlock Engine v2.
String Of Pearls in Delaware — the short answer
String Of Pearls in Delaware: hardy in zones 9–12, part sun, against a state median of ~241 frost-free days.
- Plant zones
- 9-12
- Manual horticultural correction (source not retained); NC State Extension and Missouri Botanical Garden, with the remaining rows from other published sources or Growable Ground compilation
- Delaware zones
- 7a-8a
- USDA PHZM 2023
- Frost window
- Mar 23 - Mar 23 – Nov 17 - Nov 19
- NOAA RCC ACIS 1991-2020, 28°F
- Shortest county season
- 238 days
- NOAA Regional Climate Centers ACIS, 1991-2020, county 28°F killing freeze
Plant data: Growable Ground Plant Database, compiled from FAO ECOCROP, USDA PLANTS and university Extension sources — per-field provenance varies and is published with the dataset.
Your yard isn't the whole zone.
Delaware spans zones 7a-8a, but your yard sits in exactly one — and slope, tree cover, and cold-air pockets nudge it further. Enter your address and we'll score string of pearls against your parcel's actual hardiness, soil, and sun.
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
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Where String Of Pearls Stands in Delaware
String Of Pearls is rated for zones 9–12 — a cold floor USDA puts at 20 to 30°F. No Delaware county sits inside it, so in open ground this is a grown-under-cover plant here rather than a bed plant — which is a statement about Delaware winters, not about string of pearls.
Below the zone 9 floor
3 counties
- Kent County · zone 7b
- New Castle County · zone 7b
- Sussex County · zone 7b
Winter cold is the limit here — the same plant works in a container that comes under cover.
County hardiness zones: USDA Plant Hardiness Zone Map (PHZM) 2023, per county. A zone is a 10°F band of average annual extreme minimum temperature, so the floor above is the band the plant's rating denotes, not a single measured kill point. Slope, shelter and cold-air drainage routinely move a site half a zone either way from its county figure — which is the part only your address resolves.
Zone Comparison
String Of Pearls Needs
- USDA Zones: 9-12
- Sun: Part Sun
- Mature size: 6 in tall
- Drought tolerance: High
Delaware Has
- USDA Zones: 7a-8a
- Last Hard Freeze (28°F): Mar 23 - Mar 23
- First Hard Freeze (28°F): Nov 17 - Nov 19
- Annual Rainfall: 42-48 inches
- Common Soils: Sandy loam, Silt loam, Tidal marsh
Plant Zone Range (zones 9-12)
Preferred Soil pH
Plant data: Growable Ground Plant Database, compiled from FAO ECOCROP, USDA PLANTS, and university Extension sources — per-field provenance varies and is published with the dataset. State data: USDA ARS PHZM 2023, NOAA Climate Normals, NRCS SSURGO.
When to Plant String Of Pearls in Delaware
The frost window
Across Delaware, the last spring hard freeze (28°F) clears between Mar 23 and Mar 23, and the first fall hard freeze lands between Nov 17 and Nov 19 (NOAA Regional Climate Centers ACIS, 1991-2020). Counting from the latest last freeze to the earliest first freeze, that's a 239-day window you can count on — up to 241 days on a mild site in a kind year. That marks the hard freeze, not the last light frost, so tender transplants usually wait another 2-3 weeks.
Winter standing
Delaware runs as cold as USDA zone 7, and no sourced winter-hardiness floor is on record for string of pearls, so this page does not state whether it overwinters here — and gives no fall establishment date on the strength of a guess. Whether string of pearls is a permanent planting or a replant-every-spring crop for you turns on your own zone within Delaware; check its hardiness range against that before treating it as long-lived ground.
Frost window: NOAA Climate Normals 1991-2020. Plant timing fields: Growable Ground Plant Database — frost-free days from FAO ECOCROP, days to harvest from university Extension production guides, and growing-degree-day and chill-hour minimums that are compilation estimates rather than published figures. Your site's own frost dates can run earlier or later than the state range — a parcel report pins them down.
Soil + Drainage Fit
String Of Pearls likes near-neutral soil (pH 5.5-7). That's the common-ground band across Delaware's sandy loam and silt loam — a soil test confirms it for your site. It will grow across that whole span, but it does best between pH 6.5 and 7 — worth knowing before you decide whether a Delaware soil test result is a problem or just a number. Drainage matters: this plant wants well (dry spells). If your Delaware site is heavier clay or sits in a low spot, raised beds or amendment with compost solve it.
Your land, not the state average
SSURGO maps about 19.8% of Delaware as poorly or somewhat-poorly drained, and the class flips parcel to parcel. String Of Pearls tolerates drought well, so wet feet — not dry spells — is its real risk here — your soil map unit, not the state average, is the real answer.
Check your parcel → Source: USDA NRCS SSURGO.
Plant pH requirements: FAO ECOCROP and USDA PLANTS, with the remaining rows from other published sources or Growable Ground compilation. Drainage: FAO ECOCROP, with the remaining rows from other published sources or Growable Ground compilation. Delaware soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
What Else to Consider for String Of Pearls in Delaware
Zone compatibility tells you about winter cold survival — but Delaware growers also need to think about:
Sandy soils in southern DE drain too quickly
Salt spray damage near the coast
Rising water tables in low-lying areas
Growing string of pearls here specifically
String Of Pearls rates to USDA zones 9–12 and takes frost damage on growing tissue around 35°F (FAO ECOCROP), but cold isn't the risk in Delaware — wet is: with roughly 19.8% of its soils poorly-drained (SSURGO), soggy ground rots the crown.
Give string of pearls a raised bed or mounded row with coarse amendment so its crown never sit wet. How to handle it →
What to actually do about these — and the constraints that apply to every Delaware grower, not just string of pearls — is covered on the Delaware growing guide.
Where in Delaware String Of Pearls Is Zone-Hardy
String Of Pearls is rated for USDA zones 9–12. No Delaware county reaches it. Even Sussex County, the state’s mildest winter at zone 7b, sits below the plant’s zone 9 floor — so in open ground this one needs winter protection here, or a container that comes under cover.
County hardiness zones: USDA Plant Hardiness Zone Map (PHZM) 2023, per county. String Of Pearls’s zone 9–12 band: USDA PLANTS / Growable Ground plant database. A parcel report resolves your address’s own zone and frost dates rather than its county’s.
Pollinator + Wildlife Value
String Of Pearls draws honeybees (low value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, string of pearls can only work that bloom inside Delaware's frost window — roughly 241 days, opening after the last 28°F freeze (Mar 23 - Mar 23) and closing at the first (Nov 17 - Nov 19), per NOAA Regional Climate Centers ACIS, 1991-2020.
Good to Know Before You Plant String Of Pearls
String Of Pearls is listed as toxic to dogs, cats (all) at a moderate level (ASPCA). Most listed plants only cause brief upset — a raised bed or a fenced corner usually keeps curious pets clear. Parts of string of pearls carry minor toxicity for people, so know which parts are edible before harvest.
Delaware Cooperative Extension
For Delaware-specific cultivar recommendations, planting calendars, and pest pressure for string of pearls, the canonical source is University of Delaware Cooperative Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is String Of Pearls native to Delaware?
No — the USDA PLANTS Database lists String Of Pearls as introduced rather than native in the Lower 48, so it is not part of Delaware's native flora. It grows here as a garden plant; pairing it with a few Delaware natives keeps local pollinators fed too.
Looking for plants that belong here? The Delaware growing guide lists USDA-documented natives for the state.
Native-range data: USDA PLANTS Database state-distribution records, accessed 2026-07-01.
Common Questions About Growing String Of Pearls in Delaware
When can I plant String Of Pearls in Delaware?
Delaware's last spring hard freeze (28°F) clears between Mar 23 and Mar 23, and the first fall hard freeze lands between Nov 17 and Nov 19 (NOAA Regional Climate Centers ACIS, 1991-2020). No sourced winter-hardiness floor is on record for String Of Pearls, so this page does not state whether it overwinters in Delaware and publishes no fall establishment date for it — check its hardiness range against your own zone before treating it as a permanent planting.
What hardiness zone is String Of Pearls grown in across Delaware?
Delaware spans USDA hardiness zones 7a-8a (USDA ARS PHZM 2023). String Of Pearls carries a range of zones 9-12, so the overlap zones are where outdoor growing is most reliable.
How many frost-free days does a typical Delaware site have?
A typical Delaware site sees ~241 frost-free days per year (derived from NOAA Regional Climate Centers ACIS, 1991-2020). String Of Pearls should be matched against that window, so check whether your local microclimate runs above or below the state average before settling on a planting date.
Is String Of Pearls native to Delaware?
No — the USDA PLANTS Database lists String Of Pearls as introduced rather than native in the Lower 48, so it is not part of Delaware's native flora. It grows here as a garden plant; pairing it with a few Delaware natives keeps local pollinators fed too.
How should I amend the soil for String Of Pearls in Delaware?
String Of Pearls prefers pH 5.5-7 and well (dry spells) drainage (Growable Ground Plant Database). That sits in the common-ground band across Delaware soils — a 30-minute soil test from a local Extension lab confirms it for your specific site.
Will String Of Pearls actually grow on my specific land in Delaware?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores string of pearls against your address's exact soil pH, drainage, sun, and frost-date data drawn from USDA SSURGO, NOAA, and PRISM — not state averages.
Check your specific parcel in Delaware
State-level data is a sketch. Your Growable Ground report scores string of pearls against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Delaware string of pearls averages can't show:
We read public map data around Delaware — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Delaware string of pearls average
Explore More
Growing guides for string of pearls
Explore Delaware county by county
Delaware carries 3 counties with their own USDA zone — a sample of the growing pages for string of pearls there:
Where else string of pearls grows
String Of Pearls's zone band crosses state lines — these are the states closest to Delaware in winter climate where it also has a page, plus the far ends of its range. Each one re-answers the question with that state's own record.
More to grow in Delaware
Delaware has a growing page for 1,013 plants — a rotating sample of the rest of the shelf.
Analysis by the Growable Ground research team, grounded in USDA PLANTS, USDA NRCS SSURGO, NOAA Climate Normals (1991-2020), and named Cooperative Extension sources. How we know →
Cite this dataset
Kirchick, M. (2026). Growable Ground Plant Database [Data set]. Zenodo. https://doi.org/10.5281/zenodo.21435643
Licensed CC BY-NC 4.0. DOI 10.5281/zenodo.21435643
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