Common poppy
A scarlet annual that colonises bare soil in the very first season.

The first coloniser
The common poppy is a pioneer. Its seed lies dormant in the soil for decades, waiting for ground to be disturbed. Bare soil in spring, and it's up in a fortnight.
Specs
type annual, native height 30–70 cm flower june – august soil disturbed, low-nutrient seed 1 g / m² in a mix
Why we sow it
It doesn't fight the perennials. It holds the ground for year one — shading out weeds and giving pollinators a first feed — then steps aside as the grasses come through. The red is just the bonus.