Perennial vs annual herbs indoors: which regrow and which to replant

Annual herbs such as basil, cilantro and dill complete their life cycle in one season, so indoors you harvest them until they flower and then replant. Perennial herbs such as thyme, oregano, mint, chives and sage live for years and keep regrowing after you cut them. Parsley sits in between as a biennial. Knowing which is which tells you what to keep and what to replace.

When you grow herbs indoors, there is no winter to sort out the annuals from the perennials for you. Everything just keeps growing, until one day your basil is all flower spikes while your thyme next to it looks the same as ever. That difference comes down to each herb's natural life cycle. This guide explains annual, biennial and perennial herbs, how each behaves indoors, how long to keep them, and when it makes sense to start a fresh yCube.

Key takeaways

• Annual herbs grow, flower and set seed in one season; once they flower, leaf production winds down.
• Biennial herbs, such as parsley, naturally take two years to flower, though most people grow them like annuals.
• Perennial herbs live for several years and regrow after harvesting, though they can become woody over time.
• Indoors, perennial herbs can keep growing through winter instead of going dormant.
• Replace any plant when it bolts, declines or stops being useful in your kitchen, whatever its type.

What is the difference between annual, biennial and perennial herbs?

The terms describe how long a plant naturally lives and when it flowers.

• Annual herbs complete their whole life cycle, from seed to flower to seed, in a single growing season. Basil, cilantro and dill are annuals, according to Washington State University Extension.
• Biennial herbs spread their life cycle over two years: leafy growth first, then flowers and seed. Parsley is the most familiar example. University of Illinois Extension notes that parsley is usually grown as an annual but is actually a biennial.
• Perennial herbs live for more than two years and regrow season after season. Chives, mint, oregano, thyme and sage are perennials, per Washington State and Illinois Extension.
• Tender perennials are perennials that cannot handle hard cold outdoors. Illinois Extension lists rosemary as a tender perennial.

Common herbs by type

How do annual herbs behave indoors?

Annuals are built to grow fast and finish. Indoors, that means an early stretch of quick, generous harvests, followed by a turn toward flowering. You can slow that turn with regular harvesting, a cool spot and pinching off flower buds. Washington State Extension recommends keeping basil flower spikes pinched out to encourage bushiness, and harvesting dill leaves before flower buds appear.

Eventually, though, an annual will flower and its leaves will thin out and often turn more bitter. That is the natural end of its cycle. The best strategy for annuals is succession: start a new plant before the old one finishes. Washington State notes that successive plantings over several weeks give you a long basil harvest season.

How do perennial herbs behave indoors?

Perennials are in it for the long haul. Cut them back and they regrow. Outdoors, many go dormant or die back in winter. Indoors, they can keep going. Gardyn's thyme guide notes that while thyme outdoors may go dormant in winter, growing indoors allows continuous growth and harvest.

Perennials do change with age:

• Woody herbs get woodier. Thyme, sage and rosemary build woody stems over time. Gardyn's thyme guide recommends regular pruning to promote bushier growth and keep the plant from becoming woody. With rosemary, harvest the green tips and leave the woody base.
• Vigorous herbs need trimming. Mint grows fast and fills space quickly. Frequent cutting keeps it tidy and productive. See our guide on how to grow mint indoors.
• They still flower. Perennials bloom too, but flowering does not end their life the way it does for annuals.

An older perennial can slow down or become more stem than leaf. At that point, a fresh plant may give you more to harvest than the original.

How long should you keep each herb?

On a Gardyn, Gardyn's help center says most of the plants it offers can be harvested continuously, with most lasting around 6 months. Every plant eventually reaches the end of its cycle: for greens and herbs, that usually means flowering instead of producing leaves.

A simple rule of thumb by type:

• Annuals: keep them while leafy; plan the replacement as soon as you see stretching or flower buds.
• Biennials (parsley): keep them as long as they are leafy and productive; replace once they flower.
• Perennials: keep them as long as they are productive and you are using them, and refresh when they become woody, sparse or slow.

If you want to keep a perennial longer than your indoor garden needs it, transplanting is an option for some plants. See how to transplant yCubes outdoors.

When should you replace a yCube?

Gardyn's help center suggests replacing plants that are bolting, declining, not to your taste, or when you simply want to grow something new. It also says a plant is worth keeping as long as it is productive and you are using it.

Signs it is time to start a new yCube:

• Bolting in herbs and leafy greens, such as stretching stems and flower buds. Gardyn's help center notes that bolting cannot be reversed.
• Fewer harvests than you need, or leaves that are smaller and slower to regrow.
• Fruiting plants that stop flowering. Gardyn's help center says going many weeks without new flowers is a sign the plant is nearing the end of its life cycle.
• Roots that are dark brown or black and slimy, which Gardyn's help center describes as signs of root rot that a plant is unlikely to recover from.
• You want something different. Rotating in new herbs is part of the fun.

Timing tip: you do not need to wait for a plant to finish. Gardyn's help center notes that starting new yCubes early gives them time to germinate, so the next plant is ready as the old one winds down.

Browse herbs to grow next in the Gardyn plant library, or see how Gardyn works.

Frequently asked questions

Which herbs come back every year?

Perennial herbs such as chives, mint, oregano, thyme, sage, rosemary and French tarragon regrow year after year. Annuals such as basil, cilantro and dill do not.

Is basil a perennial or an annual?

Basil is grown as an annual. It flowers and declines within a season, so most people replant it in succession.

Is parsley a perennial?

Parsley is a biennial, which means it naturally flowers in its second year. Most people grow it as an annual and replace it once it flowers.

Do perennial herbs go dormant indoors?

Indoors, perennial herbs can keep growing through winter instead of going dormant, as Gardyn's thyme guide notes. They may still slow down with age.

How long do herbs last in a Gardyn?

Gardyn's help center says most of its plants can be harvested continuously, with most lasting around 6 months. Replace any plant when it bolts, declines or is no longer useful to you.