Knock Out roses are a very hardy shrub rose and they can be planted any time the ground is not frozen, as long as you purchase them in containers. The best time would be spring so the roots can become established underground before the summer blooming season. The best planting tip for any rose is to dig a large hole twice as wide as the container that the rose comes in. Then loosen the soil on the sides of the planting hole. This will encourage the roots to spread outward and find their own supply of water and food. Improve the soil with compost and manure and use a slow release fertilizer such as Osmocote mixed into the soil at planting time. Roses are hungry and thirsty plants because they flower so often and the Knock Out rose will return your investment in good care with more flowers. Keep growing, Marianne Binetti