Home > Herbs > Basil > How to Harvest Basil Seeds

How to Harvest Basil Seeds

Harvesting basil seeds is essential for any dedicated herb gardener. As an annual herb it must be grown anew each year, so saving your own basil seeds is a must. This article has all the details on how to harvest basil seeds: collecting and preparing the seeds, and how to store them.

Harvested basil seeds in a wooden spoon.
How to harvest basil seeds.

Basil is very easy to grow at home, however it grows as an annual in most areas, meaning that it has to be regrown from seed each year.

If you allow your basil plants to flower at the end of the growing season, you can harvest seeds for successive plantings, provides an ongoing supply of this tasty herb.

It’s easy to harvest and save basil seeds, especially if you have more than a few plants. You will need to allow at least one plant to flower at the end of the growing season. This will reduce the production of new leaves that can be used as a herb.

For this reason, when growing basil I tend to grow a few plants so that I can have at least one basil plant go to seed at the end of the summer so I can save seeds for next year.

Growing Basil for Seed

There are many types of basil, such as lemon basil and Thai basil, but one of the most popular is sweet basil or Genovese basil. You may have your favorite, or you may like to try new and unusual varieties.

Either way, saving seeds from your basil plants ensures you have a supply for the next growing season of the variety you enjoy the most.

When growing basil, if you are planning on harvesting the seeds, you won’t need to pinch the tops as you would when growing it to harvest the leaves. You’ll leave the tops flower so they can produce seeds.

If growing different varieties of basil, you’ll need to place them at least 150 feet apart to prevent cross-pollination.

You may want to grow basil plants to harvest the leaves, then let them flower and go to seed later in the season, or you may want to plant a separate stand of basil for seed harvest only.

Flowering and Seed Production

Basil flowers are pretty white or purple flowering spikes at the tops of the plants, that attract bees and butterflies.

Flower buds will start to grow near the end of the summer, possibly earlier if the weather has been very hot and dry.

Normally you will pinch the tops of your basil plants to keep them productive and bushy, growing big juicy leaves to harvest. Flowers take the plant’s energy away from leaf production.

As a warm-season herb, frost kills basil, including flowers that haven’t yet gone to seed. When you want to harvest seeds, stop pinching at least 6 weeks before the first frost date so flowers mature and produce seeds.

If you are growing a stand of basil specifically for seed production, you don’t need to remove flower buds at all.

As flowers mature and drop petals, green carpels remain, where the seeds are growing. As the carpels or pods dry and brown, the seeds are also drying and maturing inside.

Basil seeds are tiny, starting as pale green round seeds that turn to brown then black.

A bundle of dry basil seed heads.
Dry flower heads before collecting basil seeds.

Collecting and Saving Basil Seeds

Step 1 – Assess Your Plants to Harvest Seeds

When collecting basil seeds to save and plant, assess your plants and gather seeds from the best plants. Choose the healthiest, strong-growing, most attractive plants (look for features that you want in your basil plants next year).

Step 2 – Look for Seeds

Look for seeds in the seed heads by gently tapping a seed head over your open palm or into an envelope. Mature seeds are tiny, round, and black. If nothing shakes loose, the seeds are not mature or dry enough yet to harvest.

Step 3 – Collect Seeds

If you have only a few plants, you can just shake dry brown seed heads into a plastic baggie or an envelope.

If you have a lot of plants to harvest seeds from, you can clip carpels (seed heads) from the plants into a large plastic baggie or bowl to separate. To do this, place the bag over the seed head and then clip it off, to prevent seeds being lost if they are shaken loose when you cut the stalk.

Step 4 – Separate seeds from the seed head

To separate the seeds from the plant material, crumble the dried carpels in a bowl, or shake them in a bag.

Use a mesh sieve to get the seeds clean of plant material.

Note: You can plant basil seeds that have some of the chaff from the carpels but clearing them of the plant material is best if you are storing them for next season.

Step 5 – Eliminate Moisture Before Storage

It’s important to make sure the seeds don’t have any moisture before storing them, as moisture will cause mold and fungus and kill the seeds.

To dry your basil seeds, spread them on a plate for a few days or in an open container, and leave them in a warm dry place.

This will allow any moisture to evaporate. Then when they are fully dry, sealing them in an air tight bag or container.

Once they are stored, if you see any moisture in the container in storage, open it up and remove the seeds. If there is no visible rotting or mold or fungus on the seeds, let the seeds dry out on a paper towel before storing them again. Remove all the moisture from the container or use a new container.

Step 6 – Label the Seed Containers

Label the container with the name of the seeds and the date collected, including the year.

It’s important to label the seeds you gather and store, especially if you collect and save other seeds from your garden, and especially if you are growing and saving more than one variety of basil.

You may think you will remember or recognize the seeds next season, but labeling with variety and date will avoid any confusion and give you a good idea of viability.

When you know how to harvest basil seeds, an important thing to remember is don’t save seeds from hybrids. You may be attracted to a unique characteristic of a hybrid variety, such as resistance to downy mildew, or being bred for extra-large leaves. But remember, hybrids are often sterile and won’t produce great seeds, or seeds that are true to type. Make sure you are growing heirloom varieties if you want to gather and save seeds.

You may also like: