When to plant cucumbers in zone 8a

Transplant outdoors around Apr 5. That is 1 weeks after zone 8a's median last frost, Mar 291. Across most of zone 8a that date falls between Mar 27 and Apr 14.

Why a range: zone 8a is defined by winter lows, not frost dates. Its ZIP codes have median last frosts from Mar 20 to Apr 72, so a single zone date can be weeks off for you. The rule comes from Oregon State University Extension Service.

Last reviewed: 2026-11-02
Stations: 650
ZIP codes: 2,528

Photo: Agung Sutrisno / Pexels

These dates use the typical last frost for the whole zone. Your ZIP code gives a closer answer.

Start indoorsOregon State, central ORStart indoors across most of the zone: Mar 6 to Mar 24Start indoors at the zone median: Mar 15 (Oregon State, central OR)
Transplant outdoorsOregon State, central ORTransplant outdoors across most of the zone: Mar 27 to Apr 14Transplant outdoors at the zone median: Apr 5 (Oregon State, central OR)
Sow outdoorsColorado StateSow outdoors across most of the zone: Mar 20 to Apr 7Sow outdoors at the zone median: Mar 29 (Colorado State)

Start indoors
Plant outdoors
Range across the zone
Frost-free season (median)
Spring frost risk (90% to 10%)
Fall frost risk (10% to 90%)

Figure 1. Cucumbers in zone 8a. Dark bars: at the zone's median frost dates. Pale bars: across most of the zone's ZIP codes. Hatched blue: where the zone's last and first frosts fall.

Start seeds indoors: Mar 152 weeks before last frost (Oregon State, central OR)
Transplant outdoors: Apr 5range Mar 27 – Apr 14

What each source says, applied to zone 8a

The same frost dates give different answers depending on whose rule you follow. These are all the published rules we hold for cucumbers, worked out at zone 8a's median frost dates.

Table 1. Cucumbers rules from every source, at zone 8a's median last frost (Mar 29) and first frost (Nov 6).
Source	What	Rule	Zone 8a median
Colorado State3Used above	Sow outdoors	On the last frost	Mar 29
Utah State4	Sow outdoors	On the last frost	Mar 29
Oregon State, central OR1Used above	Transplant outdoors	1 weeks after last frost	Apr 5
Oregon State, central OR1Used above	Start indoors	2 weeks before last frost	Mar 15
Texas A&M (E-502)5	Sow outdoors	1-6 weeks after last frost	Apr 5 – May 10
Texas A&M (E-502)5	Plant for fall	10-12 weeks before first frost	Aug 14 – Aug 28

Frost across zone 8a

Last spring frostmedian Mar 29Full range across the zone: Feb 28 to Jun 8Most of the zone (10th to 90th percentile): Mar 20 to Apr 7Zone median: Mar 29
First fall frostmedian Nov 6Full range across the zone: Sep 22 to Nov 26Most of the zone (10th to 90th percentile): Oct 31 to Nov 14Zone median: Nov 6

Frost-free season (median)

Figure 2. Frost dates across zone 8a, from 650 NOAA stations matched to 2,528 ZIP codes.

Planting cucumbers with others

Marigold Tested in a study Claimed: marigold root exudates suppress nematodes. Field tests intercropping cucumber and squash with French marigold found no consistent effect on soil nematodes.6 6 6 7 7
Blue Hubbard squash Tested in a study A border of Blue Hubbard squash, which striped cucumber beetles prefer, encircles the cucumbers; beetles concentrate on the border, which is then sprayed.8 8 8 9 9

Sources

Oregon State University Extension Service, When to start seeds indoors in central Oregon, reviewed 2024. Retrieved 2026-11-02.
NOAA National Centers for Environmental Information, U.S. Climate Normals 2020: U.S. Annual/Seasonal Climate Normals (1991-2020), 2021. Retrieved 2026-11-02.
Colorado State University Extension, Vegetable Planting Guide (CMG GardenNotes #720), reviewed September 2024. Retrieved 2026-11-02.
Utah State University Extension, Suggested Vegetable Planting Dates for Utah, January 2018; revised May 2025. Retrieved 2026-11-02.
Texas AgriLife Extension Service, The Texas A&M System, Texas Home Vegetable Gardening Guide (E-502), 2/09. Retrieved 2026-11-02.
Journal of Nematology 25(4):666-673 (Society of Nematologists); FLVC journal host, Effects of Mixed Cropping on a Soil Nematode Community in Honduras, 1993. Retrieved 2026-11-02.
University of Florida, IFAS Extension (Entomology and Nematology Department), Marigolds (Tagetes spp.) for Nematode Management (ENY-056), reviewed Reviewed November 2019; page footer "Reviewed: 01/2024". Retrieved 2026-11-02.
University of Connecticut Cooperative Extension System (UConn IPM), Protecting Cucumbers From Beetles and Wilt With Perimeter Trap Cropping, reviewed Reviewed 2012. Retrieved 2026-11-02.
University of Vermont Extension, Vermont Vegetable and Berry Program, Perimeter Trap Cropping: A Novel Approach to Insect Pest Control, July 2004. Retrieved 2026-11-02.