Zone 4 · Brassicas Growing Guide

When to Plant Broccoli
in Zone 4

Harvest the central head before flowers open, then enjoy weeks of side shoots. Temperature-sensitive — needs cool weather for heading. Medium difficulty but very rewarding.

Plant outdoors
May 1 – May 20, Jul 15 – Aug 1
Start indoors
Mar 25 – Apr 10
Last Frost
~May 1
Days to harvest
70–100 days
Difficulty
Medium
Start indoors — Zone 4
Harvest window: Jul – Sep, Oct

Planting Calendar

In Zone 4, Broccoli should be planted outdoors May 1 – May 20, Jul 15 – Aug 1, after the average last frost date of approximately May 1. Start seeds indoors around Mar 25 – Apr 10 for a head start.

Spring and fall crops. Start fall crop indoors June–July for August transplanting.

Care Guide

Sunlight
Full sun · 6–8 hrs/day
Watering
Regular
Spacing
18–24 inches
Soil
Rich, fertile, well-draining
Days to maturity
70–100 days
Soil pH
6.0–7.0
plant tip · Zone 4

Spring and fall crops. Start fall crop indoors June–July for August transplanting.

Feeding Schedule

How often
monthly
Feed type
high nitrogen then balanced
Key timing
switch to balanced when heads form

Heavy nitrogen feeder for leaf development. Switch to balanced feed once heads begin to form to avoid loose, leafy heads.

Succession Planting

Sow every 4 weeks

Start a spring crop and a separate late-summer crop for autumn harvest. Broccoli is too slow for true succession but two planned crops — one for spring harvest, one for autumn — make good use of the season.

Companion Planting for Broccoli

What you plant next to broccoli makes a real difference — some plants actively help, others compete or attract pests.

Grows well with
  • Celery
  • Onions
  • Potatoes
  • Chamomile
Keep away from
  • Tomatoes
  • Strawberries
  • Beans

These guides get better when growers like you contribute. If something’s wrong or you’ve learned something worth sharing, we’d love to hear it.

What needs correcting?

What should it say?

Your zone (optional)

Thanks — we'll review this and update the guide if needed.

Your growing tip for Broccoli

Your name (optional)

Your zone (optional)

Tips are reviewed before publishing. Accepted tips earn you a Founding Grower badge when the plant app launches.

Thanks for contributing! We'll review your tip and be in touch before launch.

Common questions

In Zone 4, start broccoli seeds indoors around Mar 25 – Apr 10, then transplant outdoors May 1 – May 20, Jul 15 – Aug 1 after your last frost around May 1. Spring and fall crops. Start fall crop indoors June–July for August transplanting.
Zone 4 has an average last spring frost of approximately May 1 and a first fall frost around Oct 1. These dates vary by specific location — use your ZIP code in the plant app for precision based on the nearest NOAA weather station.
Good companion crops for broccoli include Celery, Onions, Potatoes, Chamomile. Avoid planting near Tomatoes, Strawberries, Beans, which can compete for nutrients or attract pests.
Broccoli typically takes 70–100 days from transplant or direct sow to harvest in Zone 4. Expected harvest window: Jul – Sep, Oct.

Free app · iOS February 2028

Track your Broccoli in plant

Get a live traffic light for every crop in your garden — zone-aware planting calendar, real-time weather alerts, and a community of growers near you.

Be first to back on Kickstarter and lock in the founding price.

Broccoli in other zones
Crop Guides