When to Start Seeds in Zone 10

Starting seeds at home allows you to grow a much wider variety of crops than those at your local nursery. Instead of being stuck with standard red tomatoes and yellow sunflowers, you can fill your garden with a rainbow of colors. And growing seedlings can also help you save a bit of money. But before you stick your seeds in the soil and hope for the best, take a minute to learn the proper planting dates.

The long and warm growing season of zone 10 allows you to grow flowers and food year-round, as long as you follow the proper planting dates. I’ll cover when to start seeds to make the most of growing in this zone.

Seeds Featured in this article:

Lavender

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Munstead Lavender Seeds

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Cucumber

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Spacemaster 80 Cucumber Seeds

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Zinnia

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Senora Zinnia Seeds

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Cosmos

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Apricotta Cosmos Seeds

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Tomato

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Cherokee Purple Pole Tomato Seeds

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Bok Choy

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Baby Choi Bok Choy Seeds

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Where is Zone 10?

The recent updates to the USDA Plant Hardiness Zone Map have expanded the areas of the US that belong in zone 10. However, even after these changes, only a small portion of the continental US is considered a part of zone 10.

Most of southern Florida, the southern tip of Texas, and parts of southern California belong in zone 10. A few spots in southern Arizona also belong to zone ten. Some cities located in zone 10 include Los Angeles, Santa Barbara, San Diego, Orlando, Fort Myers, and Tampa.

What Is Zone 10’s Climate?

As the warmest hardiness zone in the continental United States, zone 10 experiences higher temperatures than most of the country. The lowest winter temperature falls somewhere in the range of 30-40°F, so locations in zone 10 receive few or no frosts. These low temperatures typically arrive in January or February; springtime frosts are unheard of.

Daytime temperatures in winter often remain in the 60s and 70s throughout the winter and rise above 90°F in summer. Summertime lows rarely drop below 70°F.

How to Determine the Right Start Date

Most gardeners use the last frost date to determine the right date for starting their seeds. But frost isn’t a major concern if you live in zone 10. You may not receive any frosts, and if you are hit with a frost or two, you can use row covers to protect your plants. 

Since you don’t have to worry about frost as much as gardeners in other growing zones, you can rely on temperature to determine when to start your seeds. Cool-season crops like greens and brassicas grow best from fall through spring since the summers are so hot. In most areas of zone ten, you can plant warm-weather crops outside as early as February. Some of these crops grow well throughout the summer, so planting more than one round of seeds allows you to enjoy healthy plants and bountiful harvests over multiple months.

Once you decide when to transplant your seedlings outdoors, you can calculate when to plant seeds indoors. If you’re unsure how long it takes a plant to go from seed to mature seedling, look to the seed packet for help. For example, the ‘Copenhagen Market’ cabbage packet instructs you to start four to six weeks before your intended transplant date.

Seeds in Zone 10

Since zone 10 has a year-round growing season, you can start seeds throughout much of the year. However, since some plants crumble under high heat and others thrive, planting seeds at the right time is a key part of growing healthy plants. I’ll cover starting seeds in spring, summer, and fall so you can enjoy your garden all year.

Starting Vegetable and Flower Seeds Indoors in Spring

Even if you escape the winter without a single frost, temperatures will still drop low enough to inhibit the germination and growth of warm-season crops like zucchini, sunflowers, and tomatoes. Starting seeds indoors in spring allows you to grow healthy seedlings that are ready to plant outdoors when the temperatures warm.

When to Direct Seed Flower and Vegetable Seeds Outdoors in Spring

Since the soil warms up early, you can successfully direct seed many crops in spring. Late winter and early spring are prime times to direct seed cooler-weather crops like greens and roots, while mid to late spring is the best time to plant beans, cucumbers, and other summer crops.

Since you can plant multiple rounds of seeds in spring, I’ve included a range of planting dates. You can plant one round of I’ve listed the preferred dates for the first round of direct seeding. Planting seeds before this range brings the risk of poor germination due to cold temperatures, and planting after this range means crops may experience heat stress.

Seeds for Fall Planting

Since spring and fall remain warm, winter is the best time to grow many cool-weather crops. Starting seeds in late summer or early fall allows you to produce transplants ready to plant outside in mid to late fall.

If you’re starting your seedlings in a protected area like a greenhouse or high tunnel, remember that high temperatures can inhibit the germination of some seeds. Starting seeds in a cool garage or air-conditioned home allows you to germinate seeds successfully during hot weather.

Final Thoughts

Due to a long, warm growing season, starting seeds in zone 10 looks different than starting seeds in cooler areas. Follow the recommended planting dates to grow a garden that thrives all year long.