Zone 3 · Squash Growing Guide

When to Plant Zucchini / Courgette
in Zone 3

The classic overproducer. Two plants feed a family — three and you'll be leaving bags on neighbours' doorsteps. Plant in hills with lots of compost.

Plant outdoors
Jun 1 – Jun 15
Start indoors
May 10 – May 20
Last Frost
~May 15
Days to harvest
45–60 days
Difficulty
Easy
Wrong season — Zone 3
Harvest window: Jul – Sep

Planting Calendar

In Zone 3, Zucchini / Courgette should be planted outdoors Jun 1 – Jun 15, after the average last frost date of approximately May 15. Start seeds indoors around May 10 – May 20 for a head start.

Direct sow after last frost or start 3 weeks early indoors. Fast producer — harvest at 6–8 inches before they become marrows.

Care Guide

Sunlight
Full sun · 6–8 hrs/day
Watering
High
Spacing
24–36 inches
Soil
Rich, well-draining, compost-amended
Days to maturity
45–60 days
Soil pH
6.0–7.5
plant tip · Zone 3

Direct sow after last frost or start 3 weeks early indoors. Fast producer — harvest at 6–8 inches before they become marrows.

Feeding Schedule

How often
every 3 weeks
Feed type
balanced (10-10-10)
Key timing
at planting and monthly

Heavy feeder — add generous compost at planting. Avoid excess nitrogen once flowering or you'll get lots of leaf and few fruit.

Succession Planting

Sow every 4 weeks

Sow a second batch 4 weeks after the first. Zucchini plants tire and become disease-prone by late summer — a second sowing gives you fresh, productive plants for the autumn harvest.

Companion Planting for Zucchini / Courgette

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

Grows well with
  • Beans
  • Corn
  • Nasturtiums
  • Marigolds
Keep away from
  • Potatoes
  • Brassicas
  • Fennel

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Common questions

In Zone 3, start zucchini / courgette seeds indoors around May 10 – May 20, then transplant outdoors Jun 1 – Jun 15 after your last frost around May 15. Direct sow after last frost or start 3 weeks early indoors. Fast producer — harvest at 6–8 inches before they become marrows.
Zone 3 has an average last spring frost of approximately May 15 and a first fall frost around Sep 15. 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 zucchini / courgette include Beans, Corn, Nasturtiums, Marigolds. Avoid planting near Potatoes, Brassicas, Fennel, which can compete for nutrients or attract pests.
Zucchini / Courgette typically takes 45–60 days from transplant or direct sow to harvest in Zone 3. Expected harvest window: Jul – Sep.

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Zucchini / Courgette in other zones
Crop Guides