How to grow Phacelia (Green Manure)

Phacelia tanacetifolia

🥕 Vegetable 🌸 Flower 🌱 Grown each year

A fast green manure with lavender-blue flowers that bees love. Smothers weeds, protects soil and adds organic matter when dug in.

At a glance: Sow early April to mid August, harvest from late May.

When to sow, plant and harvest

JanFebMarAprMayJunJulAugSepOctNovDec

Sow outdoors

Timed for a typical UK garden (last frost mid-April). The app uses your own town's frost dates.

Early April – mid August · 2 weeks before the last spring frost
Sow on Bare Ground
Rake the soil, scatter the seed evenly, rake it in lightly and water if dry. Great for beds that would otherwise sit empty.
7–21 days after “Sow on Bare Ground” · Early April – late April
Check It Has Come Up
A green carpet should be showing. It smothers weeds and protects the soil from rain.
50–70 days after “Sow on Bare Ground” · Late May – early June
Cut Down and Dig In
Before it flowers or sets seed (or when you need the bed), chop it down, let it wilt for a few days, then dig it into the top 20 cm.
14–28 days after “Cut Down and Dig In” · Early June – mid June
Wait, Then Plant
Leave the bed for 2–4 weeks while it rots down before sowing or planting the next crop.