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The best time to plant cilantro seeds outside is in the cool weather of early spring or late summer.
If you’ve been wondering when to plant cilantro seeds outside, the short answer is that this herb thrives in temperatures between 50°F and 70°F.
Planting cilantro seeds outside during these cooler windows gives you a lush, slow-growing harvest instead of a bitter, bolting mess.
In this post, we’ll break down the exact timing for when to plant cilantro seeds outside, how to adjust for your climate, and the simple tricks that keep your cilantro happy.
Let’s dig into the perfect schedule for getting those seeds in the ground.
When to Plant Cilantro Seeds Outside: The Core Rule
When to plant cilantro seeds outside really comes down to one simple truth: cilantro hates heat.
So the best time to sow cilantro seeds outside is about two to four weeks before your last expected spring frost.
That early window is perfect because cilantro can handle a light frost, and the cool soil helps germination.
For a fall crop, you’ll want to plant cilantro seeds outside about six to eight weeks before your first expected autumn frost.
The goal is to have your cilantro growing during the mild, short days of spring or fall, not the scorching summer months.
1. Spring Planting: No Need to Wait for Warmth
Many gardeners make the mistake of waiting until the soil is warm, but that delays when to plant cilantro seeds outside for optimal growth.
Cilantro seeds actually germinate best when the soil temperature is between 55°F and 65°F.
If you wait too long and the ground heats up past 75°F, the seeds will still sprout, but the plants will quickly bolt.
So as soon as the snow melts and the soil is workable, that’s your green light to plant cilantro seeds outside.
Check your local frost dates, count back two to four weeks, and mark your calendar for that sow date.
2. Fall Planting: The Second Window for Cilantro Seeds
When to plant cilantro seeds outside in the fall is just as critical as the spring timing.
You want the plants to mature as the weather gets cooler, not warmer.
Aim to plant cilantro seeds outside in late August or September for most northern climates.
In hotter southern zones, you might push that to October or even November for a winter harvest.
The trick is that cilantro grows slower in fall as days shorten, so give it a head start before frost arrives.
Fall cilantro often tastes sweeter and lasts longer because the cool nights slow down the bolting process.
Factors That Change When to Plant Cilantro Seeds Outside
Your specific location changes the answer to when to plant cilantro seeds outside.
It’s not a one-size-fits-all date, so you’ll need to think about your local climate and microclimate.
1. Climate Zone and Hardiness
If you live in a mild climate with cool summers, you can plant cilantro seeds outside almost year-round.
Coastal areas like the Pacific Northwest or parts of the UK can sow seeds every few weeks for a continuous harvest.
In hot, humid climates, your only real windows are very early spring and late fall.
So when to plant cilantro seeds outside varies wildly from zone 4 to zone 9.
Check your USDA hardiness zone and look at average monthly temperatures, not just frost dates.
2. Soil Temperature Matters More Than Air Temperature
When to plant cilantro seeds outside is often guided by soil temp more than the calendar.
Grab a soil thermometer and stick it an inch deep in the ground.
If it reads 50°F to 68°F, conditions are prime for sowing cilantro seeds outside.
If the soil is still frozen or soggy, wait a few days.
If the soil is already above 75°F, it’s too late for a spring crop, so wait for fall.
3. Succession Planting for a Longer Harvest
Instead of asking when to plant cilantro seeds outside just once, think about succession planting.
Sow a new batch of cilantro seeds outside every two to three weeks during your cool windows.
This ensures that as one plant bolts, another one is ready to take its place.
For example, plant cilantro seeds outside in early March, then again in late March, and then mid-April.
The result is a steady supply of fresh leaves without a glut that goes bitter overnight.
Best Practices for When to Plant Cilantro Seeds Outside
Once you’ve nailed the timing, the next step is setting up your garden bed for success.
1. Choose a Partially Shaded Spot
When you plant cilantro seeds outside, pick a location that gets morning sun but afternoon shade.
This shields the plants from intense heat, especially in late spring.
If you only have full sun, that’s fine for early spring sowings, but fall crops may need more shade.
2. Prepare Moist, Well-Drained Soil
Cilantro seeds outside prefer fertile, loamy soil with good drainage.
Work in some compost before sowing to give the seeds a nutrient boost.
Keep the soil consistently moist but never waterlogged during germination.
A light mulch can help retain moisture and keep the soil cool.
3. Direct Sow Instead of Transplanting
Cilantro has a long taproot that hates being disturbed.
So it’s always better to plant cilantro seeds outside directly in the ground.
If you start them indoors, transplant shock can stunt growth and cause early bolting.
Just scatter the seeds on the soil surface and press them in lightly, or cover with a quarter-inch of soil.
Signs Your Timing Is Off When You Plant Cilantro Seeds Outside
You’ll know if you got the timing wrong by watching your plants.
1. Bolting Means It’s Too Hot
If your cilantro shoots up tall, spindly stalks with white flowers, you planted too late in the spring.
This is a clear signal that when to plant cilantro seeds outside for your area has passed.
The leaves will also turn bitter and tough once bolting starts.
Don’t panic, just pull the plant and save the seeds for your next fall crop.
2. Poor Germination Means It’s Too Cold
If seeds don’t sprout after two weeks, the soil might be too cold or too dry.
Cilantro seeds outside need consistent moisture to break their dormancy.
Try lightly covering the bed with a row cover to warm the soil a few degrees.
Also, check if you buried them too deep, as cilantro seeds need light to germinate.
So, When to Plant Cilantro Seeds Outside?
When to plant cilantro seeds outside is all about hitting that cool, mild window in your growing season.
The best time to plant cilantro seeds outside is early spring, two to four weeks before the last frost, and again in late summer for fall.
Keep an eye on soil temperature, aim for cool conditions, and use succession planting for a steady harvest.
So if you’re staring at that seed packet wondering when to plant cilantro seeds outside, just remember: cool weather is your friend.