When to Plant Broccoli in Pennsylvania
Broccoli timing in Pennsylvania is a two-part calculation: when to start seeds indoors, and when to transplant outside. Get either one wrong by more than a week or two and the whole crop can bolt, sit idle, or get hit by a late frost at the worst possible moment.
The good news is that broccoli is one of the toughest brassicas you can grow. It handles real frost (down to about 26–28°F), and established plants are almost immune to light freezes. You just need to get the calendar math right, and this guide does that for every PA zone — spring and fall.
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Table of Contents
PA Broccoli Growing Season
Quick Reference
Spring Timing: The Math
Spring broccoli timing in PA has three key dates you’re working around:
- Seed start date — 6–8 weeks before transplant date. Seeds need warmth (65–75°F) to germinate and about 6 weeks to reach transplant size (4–5 true leaves).
- Transplant date — 4–6 weeks before your last average frost date. Broccoli tolerates frost, so you’re not waiting for frost-free conditions. You’re waiting for soil temperatures to hit 40°F+ and for the worst of the hard-freeze risk to pass.
- Target harvest date — needs to fall before sustained daytime highs regularly reach 75°F+. In most of PA, that’s mid-to-late June. Heading broccoli that matures in July will bolt rather than produce tight heads.
Work backward from your frost date: if your last frost is April 15, your transplant window is roughly March 20–April 5 (4–6 weeks before), and your seed-start date is early-to-mid February.
Spring Planting Dates by Zone
| PA Zone | Start Seeds Indoors | Transplant Outside | Expected Spring Harvest |
|---|---|---|---|
| 7a (Philadelphia) | Late January – mid-February | Late March – early April | Late May – early June |
| 6b (Reading, York, Allentown) | Early – mid-February | Early – mid-April | Early – mid-June |
| 6a (Pittsburgh, Harrisburg, Lancaster) | Mid-February – early March | Mid – late April | Mid – late June |
| 5b (Scranton, Wilkes-Barre, Erie) | Early – mid-March | Early – mid-May | Late June – early July |
| 5a (Mountains, Northern Tier) | Mid – late March | Mid – late May | Early – mid-July |
12-City Broccoli Planting Schedule
| City | Zone | Start Seeds Indoors | Transplant Outside | Spring Harvest |
|---|---|---|---|---|
| Philadelphia | 7a | Jan 25 – Feb 10 | Mar 25 – Apr 5 | Late May |
| Media / Chester | 7a | Jan 25 – Feb 10 | Mar 25 – Apr 5 | Late May |
| Reading | 6b | Feb 5 – Feb 20 | Apr 1 – Apr 15 | Early June |
| York | 6b | Feb 5 – Feb 20 | Apr 1 – Apr 15 | Early June |
| Allentown / Bethlehem | 6b | Feb 5 – Feb 20 | Apr 1 – Apr 15 | Early June |
| Lancaster | 6a | Feb 15 – Mar 1 | Apr 10 – Apr 25 | Mid-June |
| Harrisburg | 6a | Feb 15 – Mar 1 | Apr 10 – Apr 25 | Mid-June |
| Pittsburgh | 6a | Feb 15 – Mar 1 | Apr 15 – May 1 | Mid – late June |
| State College | 6a | Mar 1 – Mar 15 | Apr 20 – May 5 | Late June |
| Scranton / Wilkes-Barre | 5b | Mar 5 – Mar 20 | May 1 – May 15 | Late June – early July |
| Erie | 5b | Mar 5 – Mar 20 | May 1 – May 15 | Late June – early July |
| Bradford / Potter County | 5a | Mar 15 – Apr 1 | May 15 – May 30 | Early – mid-July |
Fall Timing
Fall broccoli is often better than spring broccoli in Pennsylvania — particularly in zones 6a through 7a. Heads that develop in cooling September–October temperatures are tighter, more flavorful, and less prone to bolting than spring crops maturing in rising heat. Fall broccoli also has far fewer cabbage worm and aphid problems than spring.
The timing math for fall works backward from your first fall frost date:
- Target harvest date — 2–3 weeks before your average first fall frost. This gives heads time to mature before hard freezes arrive. (Established plants can take light frost; newly formed heads less so.)
- Transplant date — count back your variety’s days-to-maturity from your target harvest date. If you want to harvest October 15 and you’re growing Arcadia (63 days), count back 63 days from October 15 to get a transplant date around August 13.
- Seed start date — 6 weeks before your transplant date. For an August 13 transplant, start seeds around July 2.
Fall Planting Dates by Zone
| PA Zone | Start Seeds Indoors | Transplant Outside | Avg First Fall Frost | Expected Fall Harvest |
|---|---|---|---|---|
| 7a (Philadelphia) | Late June – mid-July | Mid-August – early September | Nov 15–20 | October – early November |
| 6b (Reading, York) | Late June – mid-July | Aug 10 – Aug 25 | Oct 25–Nov 1 | October |
| 6a (Pittsburgh, Harrisburg) | Early – mid-July | Aug 15 – Sep 1 | Oct 15–Nov 1 | Late September – October |
| 5b (Scranton, Erie) | Early – mid-July | Aug 10 – Aug 25 | Oct 1–15 | Late September – October |
| 5a (Mountains) | Late June – early July | Aug 1–15 | Sept 20–Oct 1 | Mid-September |
Zone Planting Guide
| Zone | Spring Seed Start | Spring Transplant | Fall Seed Start | Fall Transplant |
|---|---|---|---|---|
| 5a (Mountains) | Mar 15–Apr 1 | May 15–30 | Late June–early July | Aug 1–15 |
| 5b (Scranton/Erie) | Mar 5–20 | May 1–15 | Early–mid July | Aug 10–25 |
| 6a (Pittsburgh/Harrisburg) | Feb 15–Mar 1 | Apr 15–May 1 | Early–mid July | Aug 15–Sep 1 |
| 6b (Reading/York) | Feb 5–20 | Apr 1–15 | Late June–mid July | Aug 10–25 |
| 7a (Philadelphia) | Jan 25–Feb 10 | Mar 25–Apr 10 | Late June–mid July | Mid Aug–early Sep |
Season planning: Check our month-by-month Pennsylvania planting guide to keep your garden producing all year. Browse all Pennsylvania vegetable guides for companion planting Frequently Asked Questions About When to Plant Broccoli in Pennsylvania
When should I start broccoli seeds indoors in Pennsylvania?
When should I start broccoli seeds indoors in Pennsylvania?
For spring broccoli: zone 7a starts in late January to early February; zone 6a starts in mid-February to early March; zone 5b starts in early-to-mid March. For fall broccoli: all zones start seeds in late June to mid-July. Broccoli seeds need 6–8 weeks indoors under lights before they’re ready to transplant — plan backward from your target transplant date.
Can I transplant broccoli before the last frost in Pennsylvania?
Can I transplant broccoli before the last frost in Pennsylvania?
Yes — and you should. Broccoli is frost-hardy and actually benefits from transplanting 4–6 weeks before your last frost date. Established transplants tolerate temperatures down to about 26–28°F. The caveat: small seedlings just transplanted (3–5 days in the ground) are more vulnerable than established plants. If a hard freeze is forecast within a week of transplanting, cover with a frost cloth or wait a few more days.
Is it too late to plant broccoli if it’s already May in Pennsylvania?
Is it too late to plant broccoli if it’s already May in Pennsylvania?
For spring broccoli in most of PA, May is too late — by the time transplants are established and heading begins (late June or July), heat will likely cause bolting. The exception is zone 5a and 5b, where May transplants can still produce a spring crop before heat arrives. If you’re in zone 6a or warmer and it’s past May 1, skip spring broccoli and plan your fall planting (start seeds indoors in early July for an August transplant).
What temperature does broccoli need to head up properly?
What temperature does broccoli need to head up properly?
Broccoli heads best in temperatures between 45–75°F. Below 45°F, growth slows dramatically but the plant is fine. Above 75°F sustained, the plant rushes to flower (bolt) rather than forming a tight head. For maximum head quality, you want the head-forming stage happening in consistent 50–65°F weather — which is what fall in PA provides in late September and October.
How long does broccoli take to grow in Pennsylvania?
How long does broccoli take to grow in Pennsylvania?
From transplant to first harvest, most heading broccoli varieties take 60–75 days. DiCicco (48 days) is the fastest; Waltham 29 (74 days) is on the longer end. Add 6–8 weeks to start seeds indoors and you’re looking at roughly 14–16 weeks from seed to plate. From a summer transplant for fall broccoli, expect the main head in 60–75 days, followed by side shoots for several more weeks.
Does frost improve broccoli flavor in Pennsylvania?
Does frost improve broccoli flavor in Pennsylvania?
Yes — this is one of the main reasons fall broccoli is often better than spring in PA. Light frost triggers the plant to convert starches to sugars, which sweetens the flavor noticeably. Broccoli harvested in October after a few frosty nights in the 28–34°F range is genuinely sweeter than the same variety harvested in June. The plant can handle these temperatures; just cover heads with floating row cover if a hard freeze (below 26°F) is forecast.
