Here, I reveal what the experts have nominated as their favorite longest-flowering perennials. Grow these easy garden plants and they'll brighten your space for months every year. The good news is ...

Wallflower (Erysimum ‘Bowles’s Mauve’). This long-blooming perennial produces spikes of mauve-purple flowers starting in early spring and lasting through summer. Bearded iris (Iris germanica).