The best selling weed killer brand in the UK, Roundup GC is ideal for clearing weeds from large areas with its systemic formula Roundup GC kills the weed from the inside out killing the weed right down to the roots so they can't grow back. Roundup GC starts working within hours and fully degrades in the soil allowing replanting once the weeds have been cleared. The liquid concentrate is easily mixed to make enough weed killer to clear up to 1000m2 and is best used from February to November.