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When to plant outdoor herbs depends on your local climate, the specific herbs you’re growing, and your last frost date.
The timing can feel a little tricky because some herbs love the cold while others absolutely need warm soil to thrive.
If you’ve been wondering when to plant outdoor herbs so they actually survive and flourish, you’ve come to the right place.
In this post, we’ll break down the best times to plant outdoor herbs, how to figure out your frost dates, and the difference between cool-season and warm-season herbs.
Let’s dig in.
When to Plant Outdoor Herbs: The Simple Answer
The simplest way to know when to plant outdoor herbs is to split them into two groups: cool-season herbs and warm-season herbs.
Cool-season herbs like parsley, cilantro, and dill can handle a light frost, so you can plant outdoor herbs in early spring as soon as the soil is workable.
Warm-season herbs like basil, rosemary, and oregano cannot tolerate frost at all, so you’ll need to wait until all danger of frost has passed and the soil has warmed up.
It’s really that straightforward, once you know which category your herbs fall into.
1. Cool-Season Herbs: Plant Early
When to plant outdoor herbs like cilantro, dill, and parsley is usually two to four weeks before your last expected frost date.
These hardy herbs actually prefer cooler temperatures and will bolt, or go to seed, quickly once summer heat arrives.
You can also plant outdoor herbs in this group again in late summer for a fall harvest.
That’ll give you a second crop when the weather cools back down.
2. Warm-Season Herbs: Wait for Warmth
For tender herbs like basil, the best time to plant outdoor herbs is one to two weeks after your last frost date.
The soil temperature should be at least 60°F, and the nighttime temperatures should consistently stay above 50°F.
If you plant outdoor herbs too early, a surprise cold snap can stunt their growth or kill them outright.
Patience really is key here, so resist the urge to plant those basil seedlings too early.
3. Perennial Herbs: Plant in Spring or Fall
Perennial herbs like thyme, sage, mint, and chives have a little more flexibility when it comes to when to plant outdoor herbs.
You can plant them in the spring after the last frost, which gives them plenty of time to establish strong roots before winter.
Alternatively, you can plant them in the fall about six to eight weeks before the first expected frost.
This allows the roots to get settled while the soil is still warm, and then they’ll take off in the spring.
How to Determine Your Exact Planting Dates
You can’t know when to plant outdoor herbs without knowing your local frost dates, so let’s talk about how to find those.
Your last spring frost date is the single most important number for your planting calendar.
Your first fall frost date is equally important for planning your fall garden.
1. Use the USDA Hardiness Zone Map
The USDA Hardiness Zone Map is your best friend when figuring out when to plant outdoor herbs.
This map divides the country into zones based on average annual minimum winter temperatures.
You can simply enter your zip code online to find your specific zone.
Once you know your zone, you can look up the average last frost date for your area.
2. Check Local Extension Services
Your local university extension service is another goldmine of information for when to plant outdoor herbs.
These services often publish specific planting calendars for your exact county.
They’ll have data on average frost dates that’s tailored to your microclimate.
This is way more accurate than using a generic national map, I promise.
3. Watch the Soil Temperature
Instead of relying only on the calendar, you can also use a soil thermometer to know when to plant outdoor herbs.
Warm-season herbs need soil that’s at least 60°F to 70°F for optimal germination and growth.
Cool-season herbs are fine with soil temps as low as 40°F to 50°F.
Testing your soil temperature takes all the guesswork out of the equation.
Tips for Success When You Plant Outdoor Herbs
Once you’ve figured out the ideal timing for when to plant outdoor herbs, you still need to give them the right start.
Here are some simple tips to make sure your herbs thrive in your garden.
1. Harden Off Your Seedlings
If you’re transplanting seedlings that you started indoors, you must harden them off first.
This means gradually exposing them to the outdoors over a week to ten days.
Start with just an hour or two of outdoor time in a shaded spot.
Then slowly increase their time outside and their exposure to direct sunlight.
This process prevents transplant shock and helps them adapt to the wind and sun.
2. Choose the Right Location
Most herbs need at least six to eight hours of direct sunlight each day.
When you plant outdoor herbs, pick a spot that gets full sun and has well-draining soil.
If your soil is heavy clay, consider planting in raised beds or containers instead.
Good drainage is non-negotiable because most herbs will rot in soggy soil.
3. Water Wisely
Newly planted herbs need consistent moisture to establish their roots.
However, you should water deeply but less frequently to encourage deep root growth.
Check the top inch of soil, and if it feels dry, it’s time to water.
Once established, many herbs are quite drought-tolerant and actually prefer drier conditions.
4. Mulch to Regulate Temperature
A layer of organic mulch around your herbs can help regulate soil temperature and retain moisture.
It also suppresses weeds that compete for nutrients.
Just keep the mulch a few inches away from the stems to prevent rot.
This simple step can make a big difference in the success of your herb garden.
So, When to Plant Outdoor Herbs?
The best time to plant outdoor herbs is determined by your last frost date and the specific type of herb you’re growing.
Cool-season herbs should go in the ground early in the spring, while warm-season herbs need to wait until the danger of frost is completely gone.
Perennial herbs are flexible and can be planted in either spring or fall.
By understanding your local climate and the needs of each herb, you’ll know exactly when to plant outdoor herbs for a bountiful and fragrant garden.
Now you’re ready to get those hands in the dirt and start growing.