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Troubleshooting·5 MIN READ·UPDATED MARCH

Blackout, weight, and why your radish stems came out leggy

Pale, stretched, floppy stems are almost always one of three things: too many days in the dark, not enough light after, or a warm room.

Radish microgreens with pink stems, macro

Too many days in blackout

Radish needs two days covered. Not four. Every extra day in the dark is a day the stem spends hunting for light, and it will not shorten back up once you uncover it.

Sunflower and pea take three days because they are pushing a hull. Brassicas take two.

Not enough light after the lid comes off

Once uncovered, radish wants strong light immediately. A dim room for the first twenty-four hours undoes the whole schedule. Lights on, close, and for at least twelve hours.

Colour is the tell. Rambo radish should go magenta within a day of uncovering. If it stays white, the light is too far away.

The room is too warm

Above 24°C, everything stretches. Microgreens grow best between 18 and 21°C, which is conveniently what most houses run in winter.

Weight, and when not to use it

Weight the tray during blackout for sunflower and pea — about 2–3 kg, enough to make the seedlings push. Do not weight brassicas or anything mucilaginous. It crushes them and traps water against the pad.