When to plant different plants

The short answer: plant cool-season crops like lettuce and peas 2 to 4 weeks before your last frost date, and warm-season crops like tomatoes and peppers after the last frost when soil temperatures reach at least 60°F. Your USDA hardiness zone determines those dates, so start by finding your zone online, then use the tables below to plan your planting calendar. This guide gives you specific dates, soil temperatures, and varieties that work across zones, so you can stop guessing and start planting with confidence.

Know your last frost date

Your last frost date is the average date in spring when the final freeze occurs. It varies by zone: for example, Zone 5 typically sees it around May 15, Zone 7 around April 15, and Zone 9 around February 15. You can find your exact date from your local extension service or online calculators. Once you have that date, count backward or forward to schedule plantings.

Cool-season crops: plant early

Cool-season crops tolerate light frost and prefer temperatures between 50°F and 70°F. Plant them 2 to 4 weeks before your last frost date, or even earlier if you use row covers. For a fall harvest, plant again 6 to 8 weeks before your first fall frost.

Crop	Planting window (spring)	Soil temp	Spacing	Varieties
Lettuce	4 weeks before last frost	40-65°F	8-12 inches	‘Black Seeded Simpson’, ‘Romaine’
Peas	4-6 weeks before last frost	40-75°F	2 inches apart	‘Sugar Snap’, ‘Wando’
Spinach	4-6 weeks before last frost	35-60°F	3-4 inches	‘Bloomsdale’, ‘Space’
Broccoli	4 weeks before last frost	45-75°F	18 inches	‘Calabrese’, ‘Green Goliath’
Carrots	3-4 weeks before last frost	45-85°F	2-3 inches	‘Nantes’, ‘Danvers’

Plant these as seeds directly in the ground, except broccoli which you can start indoors 6 weeks earlier. Use a soil thermometer to check temperatures; if soil is too cold, seeds rot. A simple probe thermometer costs $10 to $15.

Warm-season crops: wait for warmth

Warm-season crops need soil temperatures above 60°F and air temperatures above 50°F at night. Plant them after your last frost date, typically 1 to 2 weeks later. If you start seeds indoors, do so 6 to 8 weeks before that date.

Crop	Planting window (spring)	Soil temp	Spacing	Varieties
Tomatoes	After last frost	60-85°F	24-36 inches	‘Celebrity’, ‘Early Girl’
Peppers	After last frost	65-85°F	18-24 inches	‘Bell Boy’, ‘Jalapeño’
Cucumbers	1 week after last frost	65-85°F	12-18 inches	‘Marketmore’, ‘Straight Eight’
Squash	1 week after last frost	65-85°F	24-36 inches	‘Yellow Crookneck’, ‘Zucchini’
Beans	After last frost	60-85°F	2-4 inches	‘Blue Lake’, ‘Provider’

For tomatoes and peppers, buy transplants from a nursery or start seeds indoors. If you start seeds, use a heat mat ($20 to $30) to keep soil at 70°F to 80°F for germination. Harden off transplants for 7 to 10 days before planting by setting them outside for a few hours each day.

Herbs and flowers: timing matters too

Herbs like basil and cilantro have different preferences. Basil is warm-season, plant after last frost. Cilantro is cool-season, plant in early spring or fall. Flowers like marigolds and zinnias are warm-season, while pansies and snapdragons tolerate cool weather.

Plant	Type	Planting time	Spacing	Varieties
Basil	Warm	After last frost	12 inches	‘Genovese’, ‘Sweet Basil’
Cilantro	Cool	2-4 weeks before last frost	6 inches	‘Santo’, ‘Leisure’
Marigolds	Warm	After last frost	8-12 inches	‘French Vanilla’, ‘Crackerjack’
Pansies	Cool	4 weeks before last frost	6-8 inches	‘Matrix’, ‘Cool Wave’

Use succession planting for continuous harvest

Instead of planting all your lettuce at once, sow a new row every 2 weeks until 4 weeks before your last frost. This gives you a steady supply rather than a glut. The same works for beans and radishes. Mark your calendar with reminders, or use a simple garden planner app.

Adjust for your zone

The dates above are averages. If you live in Zone 3, shift everything later by 2 weeks; in Zone 8, shift earlier by 2 weeks. Always check local conditions: a warm spell in March doesn’t mean the frost is over. Use a frost blanket ($15 to $25) to protect early plantings if a late freeze threatens.

FAQ

Can I plant before the last frost date?

Yes, for cool-season crops. They tolerate light frost, but not hard freezes. Use row covers or cloches to protect them if temperatures drop below 28°F.

How do I know if soil is warm enough?

Use a soil thermometer. Insert it 4 inches deep in the morning. For warm-season crops, wait until it reads at least 60°F for three consecutive days.

What if I miss the planting window?

You can still plant, but yields may be lower. For example, tomatoes planted in June in Zone 5 will still produce, but later. Choose early-maturing varieties like ‘Early Girl’ (60 days) to compensate.

Do I need to start seeds indoors?

Only for warm-season crops with long seasons, like tomatoes and peppers. Cool-season crops are best direct-sown. If you start indoors, use a seed-starting mix and grow lights ($30 to $50) to prevent leggy seedlings.

The bottom line

Planting at the right time is the single biggest factor in garden success. Know your last frost date, check soil temperatures, and follow the tables above for your zone. Start with cool-season crops early, then switch to warm-season after the frost. Keep a garden journal to track what works in your microclimate, and adjust each year. With this schedule, you’ll avoid the disappointment of frost-killed seedlings and enjoy a productive harvest from spring through fall.