Soil & potting mix

Best soil for Borage (Borago officinalis)

Also called Starflower, Bee Bush.

More about borage

About Borage

Borago officinalis · also called Starflower, Bee Bush · herb

Borage is a fast, bushy hardy annual grown for its bristly cucumber-flavoured leaves and edible, star-shaped blue flowers that pollinators adore. It germinates and blooms quickly in full sun and poor soil, self-seeds prolifically, and resents transplanting. Note: despite culinary use, it is ASPCA-listed as toxic to pets, so keep it away from grazing cats and dogs.

Preferred mix: Average, well-drained garden soil

Watch for — Flopping and lodging: Tall, soft growth (worse in rich soil or shade) splays and breaks. Grow in lean soil and full sun, or give a light support; deadhead to keep plants tidy.

Why borage needs this mix

Borage is a hungry, thirsty leafy herb — it wants a rich, moisture-retentive but free-draining loam, well fed and never baked dry.

Borage grows fast and puts on a lot of soft leaf, so it draws heavily on both nutrients and water — a lean mix simply cannot keep up.
Plenty of organic matter holds moisture evenly, which prevents the stress problems (bolting, bitterness, blossom-end rot) that come from a drying-then-flooding cycle.
It still needs structure: rich does not mean airless, so grit, perlite or leaf mould keeps roots oxygenated.

For the full picture on what makes up a good mix, see our guide to the main types of soil and potting media — it explains why each ingredient above behaves the way it does.

What goes wrong with the wrong mix

The wrong soil is one of the most common reasons borage struggles, and the damage often shows up weeks later as a watering problem. For this species specifically:

A poor, thin or sandy mix starves borage — growth stalls, leaves pale, and the plant bolts to seed early.
A heavy, compacted, badly drained soil rots the roots and brings fungal problems despite all the feeding.
Letting a rich mix dry to dust then drowning it causes the classic moisture-stress disorders this crop is prone to.

Under-feeding and inconsistent moisture. Borage needs genuinely rich soil plus steady watering — most disappointing crops come down to one or both being short.

pH — does it matter for borage?

Borage does best around pH 6.0-7.0 (slightly acidic to neutral). It is worth a cheap soil test for an outdoor bed; very acidic soil benefits from a little lime well before planting.

If you want to check or adjust it, the soil pH guide walks through testing and the safe ways to nudge a mix more acidic or more alkaline.

DIY mix vs a bagged one

For containers a good multipurpose or vegetable compost works for borage with extra feed through the season. For beds, the real win is digging in plenty of well-rotted compost or manure — that beats any bag.

Drainage and the pot

Rich but free-draining is the target: raised beds and large containers both deliver it. Mulch heavily to even out moisture and roughly halve how often you water.

Borage is usually grown for a single season, so "repotting" means starting fresh each year — never reuse exhausted, disease-prone compost for the same crop family. When the time comes, our repotting guide for borage covers the timing and technique step by step.

Borage soil — frequently asked questions

What is the best soil mix for borage?

3 parts rich peat-free compost : 1 part well-rotted garden compost or manure : 1 part perlite or grit (containers) / leaf mould (beds). Borage grows fast and puts on a lot of soft leaf, so it draws heavily on both nutrients and water — a lean mix simply cannot keep up.

Can I use normal potting soil for borage?

A poor, thin or sandy mix starves borage — growth stalls, leaves pale, and the plant bolts to seed early. For containers a good multipurpose or vegetable compost works for borage with extra feed through the season. For beds, the real win is digging in plenty of well-rotted compost or manure — that beats any bag.

Does borage need a special pH?