How to Grow Hydrangeas in Colorado
- 1). Buy a variety of hydrangea that is hardy in your zone. Your local garden center will be able to tell you which varieties will survive in your zone.
- 2). Select a planting site with well-draining soil that does not collect standing water. The site should get partial shade during mid-day and should provide protection from winter winds. Do not plant in a valley or depression where cold air can settle.
- 3). Remove weeds from the area after the last frost. Use a hand spade to dig out the weeds if they will not come out when you simply pull them up.
- 4). Lay a 2-inch layer of compost and a 1-inch layer of peat moss over the site and turn them into the soil with a garden tiller to a depth of 6 to 8 inches. These organic materials will make the soil slightly acidic, which is the hydrangea's preferred soil condition.
- 5). Apply a general purpose fertilizer once a year in the early summer to encourage blossom growth. Do not apply fertilizer past July, so the plant has time to prepare for coming colder weather. Water the hydrangeas once a week during the spring and summer and allow the plants to die back during the winter.
- 6). Prune the hydrangea in the early spring. The pruning method will vary with your exact variety of hydrangea, but most varieties that are hardy in the cold produce blooms on new wood. This means you will need to cut back old wood branches in the early spring with garden shears to encourage the growth of new branches.
Source...