New Hydrangeas that grow in our zone!

By Melanie Mathieson
Gardening Guru

Former columns on hydrangeas explained the differences between the types of hydrangeas and how to grow them. The column describing the different types of hydrangeas cautioned the gardener that very few varieties are actually suited to survive in our growing zone so be careful when you are out shopping. The good news is that this column is to inform you that there are some new varieties of hydrangeas on the market and coming to our area that will actually survive in our Zone 4.
The newest varieties to hit the garden centres and seed catalogues are called the Endless Summer varieties, “Original” and “Blushing Bride”. These hydrangeas were developed in St. Paul, Minnesota at Bailey’s Nurseries and I have been told by some of our local nursery suppliers that they will be stocking these varieties this spring as well as a few other interesting varieties being released for the first time in 2007.
The Endless Summer varieties are mopheads with showy, semi-double florets that last all summer long. The blossoms will get up to eight inches in diameter. These varieties are not just fall bloomers like the “Annabelle”, the blossoms appear in mid-June and then continue on throughout the summer. To encourage reblooming remove the spent flowers throughout the season. The foliage is dark green and supported by strong upright branches. These are the first Hydrangea macrophylla varieties that bloom on both old and new wood. Because the stems are strong this variety can be cut and enjoyed indoors in a vase. Like other hydrangeas the Endless Summer varieties also dry well but do not maintain their pink, blue or white colours when drying. Another great feature is that the Endless Summer varieties have proven to be more mildew resistant than other macrophylla varieties that wee are familiar with..
The Endless Summer “Blushing Bride” variety has pure white blossoms that mature to a blush pink and the Endless Summer “Original” has coloured blossoms. Yes I said coloured blossoms, just like the varieties that we see in the floral shops. The Endless Summer “Original” hydrangea blossoms are either blue or pink depending on the pH of the soil it is planted in. Pink blossoms indicate alkaline (basic) soils and blue blossoms indicate acidic soils. As with many of the hydrangeas, these varieties prefer partial shade.
While these new varieties have been hybridized with our climate in mind it is still important that you care for your new plant the correct way. Fortunately these new varieties are quite vigorous and easy to grow.
When you are ready to plant your new hydrangea you need to follow the rules I have laid out numerous times for planting shrubs and perennials. Start by digging a hole two to three times larger than the pot. Carefully remove the container and cut any encircling roots apart with pruning shears. Roughen the sides of root ball with your fingers by tugging gently at the perimeter of the ball to loosen tight roots. This allows for better root penetration. In the bottom of the hole add a few inches of compost before placing the plant in the hole. A fertilizer with a high middle number (phosphorus) can be mixed in the soil to promote good root growth. Now centre the plant in the hole, setting the plant level with the ground. Backfill the soil to three-quarters full and then water thoroughly, once the water has soaked in you can fill the soil in level to the ground. Water thoroughly again. As mentioned in previous columns it is a good idea to add two to three inches of mulch making sure to keep it away from the base of plant. Make sure to maintain moist soil conditions. Do not over water but do not allow the plant to get dried out either.
These new varieties are suited for our climate but to ensure that your investment survives its first winter here are a few tips to follow. To help the plant harden off for the winter you should stop all fertilizer applications after the middle of August but make sure you keep the ground moist until the ground is frozen. For extra protection for the winter season make sure to cover the base of the plant with at least four inches of mulch (leaves, straw, bark etc.). There is no need to cover all stems to the tip or to cut them back. Only apply the mulch to the plant when it is fully dormant, usually by the end of October in our area. Once the ground is no longer frozen in the spring you can uncover the plants. The plant will begin to grow from the base of the plant and any old branches that survived winter. Be patient, as growth will come slowly until the heat of late spring stimulates the plant to grow faster.
Watch for these varieties next spring in your local nursery and next fall you’ll be enjoying some spectacular blooms.