What Month Should You Start An Herb Garden For Best Growth?

young cilantro seedlings in flat

When you can buy herb seeds year-round, and nurseries carry herb seedlings as early as March and as late as July, it’s tricky to know precisely when to get your herb garden started.

You don’t want to wait too long and miss the growing season, but you also don’t want to start too early and have to deal with replanting later on. So when is the optimal time to start an herb garden?

April or May are two good months to start an herb garden from seed or seedlings. Quick-growing summer crops like basil and cilantro will have time to grow to seedling size before you plant them out, and it’s the right time for many nurseries to have seedlings for slow-growers like rosemary and thyme.

If you’ve missed the April-May “deadline,” don’t worry. There’s some wiggle room built into this general rule of thumb. An herb garden started in June or July will still produce as long as you choose the right herbs with a shorter time to maturity.

When should you start an herb garden?

April and May are the best months to start your summer herbs and buy herb seedlings. Planting during these months gives you enough time to start most seeds indoors before transplanting them into the garden and provides a long season to harvest fresh herbs.

That said, if you’re starting slower-growing herbs like thyme or rosemary from seed, you will need to begin the process earlier, ideally January-February. The extra weeks give your seeds time to establish themselves before transplanting outdoors and the best chance of success.

The following table gives an overview of herbs that can tolerate extra early planting and which should be direct sown.

NameTypeCold toleranceTransplant tolerance
CilantroAnnualModerateYes
MintPerennialModerateNo
ParsleyAnnualYesNo
OreganoPerennialYesYes
SagePerennialYesYes
RosemaryPerennialYesYes
BasilAnnualNoYes
DillAnnualNoNo
AnisePerennialNoNo
ChivesPerennialYesYes
ThymePerennialModerateYes
Some of the most common herbs are easy to start indoors and produce for all season.

The best time to start annual herbs

You can start annual herbs such as basil, cilantro, and dill alongside your other vegetable and flower crops 4-6 weeks before the last frost of the spring. After establishing themselves indoors, the seedlings will be ready to harden off and transplant in the garden by May when the weather is consistently warm. 

mixed garden bed of basil, kale, salvia
I started these basil plants in June, and this is their growth in July. It was my second round of basil plants that I squeezed in for the summer.

Annual herbs are typically easy to find at the nursery or garden center starting in spring. Buying a seedling will give you a headstart on your garden, letting you skip the seed-starting process. 

Buying seedlings is also a great option if you’re late to get your garden set up, have just moved to a new house, or, like me, got distracted by your kids too many times and forgot to water your own starts, leaving them to wither away slowly. Sorry, seedlings!

To find the best date to start your annual herbs, you’ll need to know your last frost date, which you can look up at Dave’s Garden by using your zip code. This date is approximately the last time your area could have temperatures low enough to freeze, which will kill many tender herbs.

Once you have that date, count back 4-6 weeks, and you’ll know when to start your annual herbs. For example, if your last frost date is May 1st, start herbs such as basil, cilantro, and parsley mid to late March.

If you’re planning to buy seedlings, start shopping the nurseries at the beginning of May.

What about perennial herbs?

Most herbs are perennials, which live for more than one season and continue to grow as the years pass by. You can start perennials such as sage and rosemary from seed during late winter. They’ll be ready to harden off and transfer to the garden by late spring.

Be aware that perennial herbs tend to be very slow growers, and you’ll need to baby the seedlings much longer than annual herbs. They’ll also need more time to grow large enough to harvest, so buying a seedling can be a real timesaver.

Some herb seeds, such as lavender, are notoriously tricky to germinate, so I’d recommend saving yourself the frustration and buying a few seedlings. The same goes for rosemary and mint, which I’ve never had luck with starting from seed.

Other perennials, such as chives, are easy to start from seed and relatively quick to harvest. You can always mix and match which herbs you start from seed and which you buy as a time-saving seedling.

When should I start herb seeds indoors?

Starting herb seedlings indoors gives you control over soil conditions and temperature and allows you to plant herbs earlier than you could outdoors. Starting seeds early in the year will also enable you to provide slow-growing herbs such as mint, parsley, and oregano with a head start.

young cilantro seedlings in flat
Cilantro is easy to start from seed in early spring.

Speaking of parsley, some herbs prefer to be “sown where grown” and resent transplanting. Parsley is one of them, also with dill. Both herbs have long taproots, often making them better candidates for direct sowing in the garden. You can still start them indoors when it’s convenient; just take extra care when transplanting.

On the other hand, direct sowing lavender will be all but impossible because they’re so slow to germinate, and you need to monitor the soil moisture.

Whether to start indoors or direct sow depends on your space, time, and which method will be easier for you to take care of your plants.

When can herb seedlings go outside?

If you don’t have the space, time, or energy to start herb seedlings indoors, you can choose the easy option of purchasing seedling trays and planting them directly into your garden. 

It’s best to plant purchased seedlings at the same time that indoor seedlings would be transplanted outdoors – during April or May. Planting during late spring minimizes the chance of frost damage, and gives you time to enjoy a prolonged harvest over the summer months.

Harden off your seedlings before transplanting them

Seedlings grown indoors are accustomed to ideal growing conditions such as warm temperatures, no harsh sunlight or winds, and regular water. They need to be hardened off before transplanting to gradually transition them from their cozy indoor environment to the great outdoors.

You can harden off seedlings in 1-2 weeks by slowly introducing them to their new outdoor conditions. Start by setting them outside in a protected spot for an hour or two the first day, gradually increasing the time they spend each day outdoors.

mixed seedlings of basil, cucumber, other vegetables
This mixed selection of seedlings I started indoors is in the hardening-off process. It includes my second round of basil and cilantro, which I can never grow enough of.

Be sure to bring them inside at night the first few nights, as they’re still not acclimated to cooler nighttime temperatures.

By the end of the week, your seedlings should be ready to plant in their permanent spot in the garden.

For a more detailed, step-by-step guide, jump over to this article:

When is it too late to start an herb garden?

You can make a mid-summer planting in June or July for heat-loving, fast-growing herbs such as basil. However, you’ll have a shorter harvest window, and the plants might now grow as big as those started earlier in the season.

You can extend the odds of a successful late start by choosing herbs that perform well in cooler weather, such as cilantro, chives, mint, and borage. Avoid the slow-growers like lavender and thyme if you’re starting from seed.

If you can still find seedlings, try planting them into a pot that you can overwinter on your patio, porch, or balcony, which will be semi-protected from the winter weather. The herbs will jump into action with new growth in spring, and you won’t need to replant.

FAQ

Can I plant herbs in August?

August is a great time to plant seedlings of perennial herbs such as rosemary, lemon balm, mint, or sage. They’ll have time to establish themselves in the final months of the growing season and will overwinter easily in the garden. In the spring, they will be flush with new growth.

Will herbs come back each year?

Perennial herbs such as chives, rosemary, thyme, sage, and mint will come back each year, even if they die back during winter. Annual herbs such as basil, cilantro, and dill will not come back each year, although dill readily reseeds with new plants.

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