Borage Seed: Saving It and Keeping the Self-Sown Colony in Check

The seed drops fast, so catch it before it falls

Borage sets seed continuously while it is still flowering. Each flower leaves four seeds sitting in the green calyx cup, and they ripen from green through gray to hard black over roughly two weeks, at which point the cup opens and they fall straight to the ground. There is no drying pod that holds on and no window of a month to come back to it.

So collect from the plant every few days through the second half of the flowering period rather than making one trip at the end. Look for the calyx cups on the oldest, lowest flowering stems first, tip the stem over your hand, and take the seeds that are already black and hard. Gray seed will finish ripening indoors on paper; green seed shrivels to nothing.

1. Work along the stem from the base Flowers open from the base of the curled stem upwards, so the ripe seed is always at the bottom end. Start there and ignore the tip.
2. Tip the stem into a bowl Bend the flowering stem over a shallow bowl and tap it. Anything ripe drops out on its own. Do not pick the calyx cups off, leave them to ripen more.
3. Slide a tray under a good plant If you want a lot of seed, lay a sheet or a tray under the plant for a fortnight and simply collect what falls. Far quicker than picking by hand.
4. Dry for a week before storing Spread the seed one layer deep on paper somewhere dry and airy for a week. Bagged straight from the garden it goes moldy within days.

Borage seed does not keep well compared with most annuals. Expect good germination for two years and a steady decline after that, so collect fresh seed each season rather than relying on an old packet.

Seed comes true, which makes saving it worth doing

Borage is heavily worked by bees and crosses readily with other borage nearby, but since almost everything grown in gardens is the same blue flowered plant, saved seed comes true in practice. The seedlings look like the parent and flower the same color. The occasional white flowered plant that turns up in a batch is worth keeping separate if you want to hold that line, and it needs real isolation from blue plants to stay white.

The traits actually worth selecting for are not color. Save from the plants that stood up rather than flopped, that flowered longest, and that came through the driest spell without checking. Mark them while they are flowering, because by seed time every plant in the row looks equally tired and you will not remember which was which.

Volunteers: one plant becomes a colony

A single borage plant left to shed drops several thousand seeds in a circle roughly its own width around itself, and a good proportion come up the following spring. The rest sit in the soil and germinate over the next two or three years, which is why a bed that had borage in it once keeps producing seedlings long after you stopped growing it deliberately. In a wild corner or an orchard that is a free crop of bee plants; in a vegetable bed it is a weed that shades out a row of carrots in a month.

The seedlings are unmistakable and easy to remove while small: two large fleshy seed leaves, then dark bristly true leaves. Pull them at the two true leaf stage, when the taproot comes out whole in damp soil. Left until they have five or six leaves the taproot snaps and the stump regrows, and by then hoeing has stopped working.

1. Decide the boundary before it seeds Choose in midsummer where volunteers are allowed. Cut and pull the plants standing outside that area before their first seed goes black.
2. Do one weeding pass in late spring Go through the beds when the volunteers have two or three true leaves and pull everything you do not want. One thorough pass beats six casual ones.
3. Keep the best spaced ones Where you want the colony, thin the volunteers to eighteen inches (45 cm) as you would a sowing. A dense self sown stand stretches and mildews by midsummer.
4. Do not dig the bed to clear it Digging buries fresh seed and brings up older seed to germinate. Surface hoeing and hand pulling exhaust the seed bank faster.

Cutting a plant down in autumn does nothing to the seed already lying in the soil. If you want no volunteers at all, the plant has to be pulled before the first seeds turn black, which is usually well before it stops flowering.

Moving a volunteer, and why cuttings do not work

A self sown seedling can be moved, but only in a narrow window. At the two leaf stage, lifted with a trowel and a good lump of soil and watered in immediately, it takes without checking. Beyond four leaves the taproot is several inches long and brittle, and a plant moved at that stage sits still for a month and then bolts straight into flower on a stunted frame.

Cuttings are not a practical route with borage. The stems are hollow and full of water, and a cutting collapses or rots long before it makes roots. Division is equally pointless because the plant is an annual with a single taproot and no crown to split. Seed, whether sown or self sown, is the only method, and since it germinates in under a week in warm soil there is no reason to want another.

Record what you saved and where it came from

Label every envelope with the year, because borage seed loses viability faster than most and a batch that has lost its date is a batch you cannot trust. Add the parent plant's position and one word about why you chose it, such as upright or long flowering, so that the selection you made this summer actually carries into next spring instead of being forgotten.

Keep a sketch of where each plant stood, and mark on it the area you allowed to self seed. Next spring that sketch tells you at a glance which seedlings are volunteers to be thinned and which patch of bare soil is waiting for a fresh sowing. Note the germination rate of any seed more than two years old as well, so you know whether to sow it thicker or throw it away.