Borage Growing Calendar: Sowing, Cutting Back and Seed Drop

The year at a glance

Borage is a hardy annual that goes from seed to flower in about eight weeks and then flowers for six, so a single sowing occupies its ground for roughly four months. Everything below hangs off the sowing date rather than the calendar, which is what makes it portable between climates. The two decisions that shape the season are the hard cut back at midseason and whether the plant is allowed to shed seed at the end.

Spring: sow early, then leave it alone

Borage is one of the first things that can go in, because the seed germinates in soil at 50F (10C) and the seedlings shrug off a light frost. Cold soil, though, means three weeks at the two leaf stage in front of the slugs. Waiting for 60F (15C) gives emergence in under a week and a stronger plant.

Choose the ground before the seed. Full sun, free draining, and deliberately unimproved: do not sow borage into a bed that has just had compost or manure worked in, because that is the direct cause of the flopping later in the year.

1. Pick the poor sunny corner Six hours of direct sun and thin, free draining soil. Skip the feed entirely, this season and next.
2. Sow two seeds every 18 in (45 cm) Half an inch (1.5 cm) deep, firmed down, watered once. Thin to the better seedling at two true leaves.
3. Plan the successions now Note a second sowing four to five weeks out and a third in early summer. Continuous flowers come from staggered sowings, not from one plant.
4. Watch for slugs for one week Two torchlit evenings after emergence covers almost all the risk. After the fourth leaf the bristles harden and slugs stop.

In mild areas a late summer sowing overwinters as a small rosette and flowers weeks before anything sown in spring. It is the earliest bee forage in the garden and costs nothing to try.

Early summer: fast growth, and the aphids arrive

From the fourth leaf onwards borage grows fast, putting down a taproot that will carry it through dry weather. Nothing needs doing here except watching. Do not water on a schedule, do not feed, and do not stake yet.

Blackfly turn up on the growing tips at about the same time as the first flower buds. Check the angle where each flowering stem leaves the main stem once a week. A moderate colony is useful, feeding the hoverflies and ladybirds that go on to clean the beans, and no spray belongs on a plant this heavily worked by bees.

Midseason: pick daily, then cut it back hard

The first flower opens about eight weeks after sowing and the plant then gives thirty to fifty flowers a day for six or seven weeks. Pick every morning: taking the flowers keeps it producing and slows the seed set, so harvest and tidying are the same job. Pull each flower by its black anther cone so the star comes out of the calyx whole.

When the lowest third of the leaves yellow, the tips thin and the first white mildew shows, cut the whole plant back to eight to ten inches (20 to 25 cm). This is the most valuable job of the borage year and is routinely left too late. Clear the cuttings off the crown, water well, and a second flush follows in three to four weeks.

1. Pick in the morning, blue flowers only Fully open and still blue, pulled out of the calyx by the black cone. Leave the pink ones and roughly half the open flowers for the bees.
2. Cut when the plant tells you, not on a date Yellowing lower leaves plus thinning flowers plus the first mildew is the signal. Usually six to seven weeks after the first flower.
3. Take it down by half to two thirds Shears, one pass, every stem to the same height. A timid trim of a quarter does nothing and the plant stays leggy.
4. Water the day before, clear the debris after A watered plant regrows in a fortnight. Cut material left on the crown holds wet against it and rots the base.

The cut back and the seed control are the same operation if you time it right. Cutting before the first seeds turn black removes most of the season's self seeding in one go.

Late season: the seed decision, then frost

The second flush runs until the first hard frost, which blackens the plant overnight. Before that, one decision cannot be deferred: whether this plant is allowed to shed. Each faded flower drops four seeds within about two weeks, and a plant left alone for the last month puts several thousand seeds into a circle around itself.

If you want the colony, leave the final flush alone and expect volunteers all round the parent. If you do not, pull the plant as soon as the first black seeds appear in the calyx cups on the lowest stems. Saving seed sits in between: tip the stems over a bowl every few days and take what is hard and black.

Frost kills the plant but does nothing at all to the seed already in the soil. Clearing the dead stems in autumn does not prevent next spring's seedlings, and some of that seed will still be coming up two or three years later.

The four dates worth writing down

Borage is driven by intervals rather than calendar dates, and those intervals belong to your soil and climate. Four dates per plant give the whole picture: sown, first flower, cut back, second flush started. Two seasons of that and you can plan continuous flowering to the week.

Add the position of every plant on a sketch of the bed, and mark the area you allowed to shed seed. Next spring that sketch tells you where the volunteers will be, which to keep, and where there is bare ground waiting for a fresh sowing.