Zone 10 · Tomatoes Growing Guide

When to Plant Heirloom Tomato
in Zone 10

Extraordinary flavour that supermarket tomatoes can't touch. More prone to cracking and disease than hybrids, but worth every bit of the extra attention.

Plant outdoors
Jan 15 – Feb 15
Start indoors
Nov 15 – Dec 15
Last Frost
~Jan 15
Days to harvest
75–90 days
Difficulty
Medium
Ready to harvest — Zone 10
Harvest window: Mar – Jun

Planting Calendar

In Zone 10, Heirloom Tomato should be planted outdoors Jan 15 – Feb 15, after the average last frost date of approximately Jan 15. Start seeds indoors around Nov 15 – Dec 15 for a head start.

Cool season focused. Heat ruins heirloom texture and flavour faster than hybrids.

Care Guide

Sunlight
Full sun · 8–10 hrs/day
Watering
Regular
Spacing
36–48 inches
Soil
Rich, well-draining loam, heavily composted
Days to maturity
75–90 days
Soil pH
6.0–6.8
plant tip · Zone 10

Cool season focused. Heat ruins heirloom texture and flavour faster than hybrids.

Feeding Schedule

How often
every 2 weeks
Feed type
tomato feed (high potassium)
Key timing
start when first flowers appear

Heirlooms are hungrier than hybrids. Rich compost at planting plus regular liquid feed during fruiting.

Companion Planting for Heirloom Tomato

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

Grows well with
  • Basil
  • Borage
  • Marigolds
  • Carrots
Keep away from
  • Fennel
  • Brassicas
  • Corn
  • Potatoes

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 Heirloom Tomato

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 10, start heirloom tomato seeds indoors around Nov 15 – Dec 15, then transplant outdoors Jan 15 – Feb 15 after your last frost around Jan 15. Cool season focused. Heat ruins heirloom texture and flavour faster than hybrids.
Zone 10 has an average last spring frost of approximately Jan 15 and a first fall frost around Dec 31. 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 heirloom tomato include Basil, Borage, Marigolds, Carrots. Avoid planting near Fennel, Brassicas, Corn, Potatoes, which can compete for nutrients or attract pests.
Heirloom Tomato typically takes 75–90 days from transplant or direct sow to harvest in Zone 10. Expected harvest window: Mar – Jun.

Free app · iOS February 2028

Track your Heirloom Tomato 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.

Heirloom Tomato in other zones
Crop Guides