How to Sow Borage Seed: Depth, Spacing and Why Not to Transplant

Sow direct, half an inch deep, where the plant is to stand

Borage seed is large, dark brown to nearly black, ridged along its length and easy to handle one seed at a time. Sow it half an inch (1.5 cm) deep. It germinates in darkness and sown on the surface it dries out and rots rather than sprouting, so cover it properly and firm the soil down over it with the flat of your hand.

Sow it where it is to grow. Borage makes a thick, brittle taproot within the first fortnight and a plant lifted out of a module or a seed tray checks badly: it sits still for two or three weeks, then flowers early on a stunted frame and dies in high summer instead of carrying on. A seed sown direct three weeks after a transplant will overtake it and outlast it.

1. Make a hole, do not scatter Push a finger into loose soil to the first joint, drop one seed in, and close the soil over it. Scattered seed germinates unevenly because half of it ends up too shallow.
2. Sow two seeds per station Put two seeds two inches (5 cm) apart at each spot you want a plant, and pull the weaker one once both have true leaves. Germination is good but not perfect.
3. Water once, then leave it Soak the row after sowing and do not water again until the seedlings are up unless the surface bakes dry. Borage seed rots in cold, permanently wet ground.
4. Mark the row The seedlings take one to three weeks to appear depending on soil warmth, which is long enough to hoe through them by accident. Put a cane in at each end.

Do not soak or chill borage seed. It needs no treatment of any kind, and soaked seed handled with wet fingers sticks together and gets sown in clumps.

Soil temperature decides how fast it comes up

Borage will germinate in cool soil, which is why it is one of the first things a gardener can sow outdoors, but cool soil is slow soil. At the bottom of its range you wait three weeks and lose seedlings to slugs while you wait. Once the soil is above 60F (15C) the whole row is up inside a week and grows away too fast for slugs to matter.

Spacing: give it far more room than you think

A borage plant grown well reaches two to three feet (60 to 90 cm) tall and sprawls just as wide once the stems start to lean, and the packet spacing of nine or twelve inches is written for a plant kept short in poor ground. In a decent bed, plants at twelve inches close over into a single mass that mildews from the middle out and cannot be picked from.

Space plants eighteen inches (45 cm) apart in a row and keep rows two feet (60 cm) apart. If you want a solid block of flowers for bees, fifteen inches (38 cm) is the tightest that still lets air through. Grown in a container, one plant to a twelve inch (30 cm) pot is the limit, and it will still need the pot weighted or it blows over.

Borage stems are hollow and snap rather than bend. Anything planted close enough to be leaned on gets crushed, so keep it off the windward side of lettuce and young brassicas.

Thinning, and telling the seedling from a weed

The seed leaves are large, thick and smooth, more like a bean than a herb, and the first true leaves that follow are already dark green and covered in stiff white bristles that you can feel with a fingertip. That bristle is the identification: nothing else likely to come up in a herb bed is prickly at the two leaf stage.

Thin to final spacing at the two true leaf stage and not later. Pull the surplus, do not cut it, and do it when the soil is damp so the taproot comes out whole. A seedling left until it has four or five leaves has a taproot several inches long that breaks when pulled, and the stump regrows.

1. Thin in two passes Take the row down to six inches (15 cm) apart first, then a week later to final spacing. That way slug losses in between do not leave gaps you cannot fill.
2. Keep the shortest, not the tallest A seedling that is racing ahead in height is usually stretched towards light and will flop first. Keep the stocky, dark, wide leaved ones.
3. Move a thinning only if it is tiny At two leaves a seedling lifted with a trowel and a lump of soil will take. Beyond that the taproot is too long to move and the plant never recovers properly.

Sowing in succession, and what to write down

One sowing of borage flowers for about six weeks and then goes over, so a garden that wants blue flowers and bees from late spring to first frost needs two or three sowings. Sow the first as soon as the soil is workable, the second four to five weeks later, and a third in early summer for autumn flowers. After midsummer a new sowing will grow but flowers thinly and is rarely worth the ground.

Record the sowing date, the soil temperature if you take it, and the date the first seedling shows for each batch. After two seasons you will know exactly how many days your ground takes at each point in spring, which is the single most useful number for planning the successions. Note the position of each sowing on a sketch of the bed as well, because borage self seeds heavily and next spring you need to know which seedlings are volunteers and which are yours.