Growing Hydrangeas in Pots

I adore the big bodacious blooms of Mophead Hydrangeas such as ‘Endless Summer’ and the New England classic, ‘Nantucket Blue,’ but getting these shrubs to bloom reliably in US Hardiness Zones 5 and under can be a challenge.

Hydrangea Macrophyllas, also known as Bigleaf Hydrangeas or Mophead Hydrangeas, are hugely popular and relatively easy to grow but in colder areas that are on the cusp of their growing range, it’s not always easy to get them to bloom.

One reason for blossom failure is that many of these plants form flower buds on vulnerable new wood which can be damaged by late spring frosts resulting in fewer or even no summer blooms. Another reason is that many people prune the flower buds right off the plant without even knowing it while they’re tidying up in early spring! In addition, too much shade, too much sun or not enough moisture can also affect blooming. Fortunately, by planting hydrangeas in pots, we can avoid many of the problems which garden-grown shrubs face.

For success with potted hydrangeas, follow these tips:

Start with a smaller-sized hydrangea variety and a large, lightweight pot that will allow room for the shrub to grow and be happy for about three years. Plant your hydrangea using a quality, moisture-retentive potting soil. Leave a couple of inches of space at the top of the pot so that you can water thoroughly to the brim without it spilling over. Fertilize through the growing season with a liquid organic fish/seaweed blend according to directions. As a finishing touch, add some pretty annual spiller plants such as sweet alyssum, petunias or fuchsias around the base to fill out a newly planted pot!

By potting up your hydrangea in a lightweight container, you can easily move it in and out of direct sunlight as needed during the growing season. You can also place your pot close to the house where deer are less likely to stray and move it inside whenever severe weather threatens. When your hydrangea shows signs of roots coming through the bottom or top of its container, or you find you need to water more frequently, it’s time to upgrade to a larger pot.

Hydrangeas grow best with morning sun, afternoon shade and even moisture. Plants will become stressed, droop and drop leaves when pots dry out, so paying attention to watering is crucial for your potted hydrangea’s health. During the heat of summer, you may have to water thoroughly once a day. Always water early in the morning so that the leaves can dry before the hot sun reaches them; this will protect the foliage from water droplets which can intensify sunlight and burn delicate leaves.

In late November, move your potted hydrangea inside an unheated garage or another cold-storage area where it will safely sleep out of the harsh winter weather until spring. Water sparingly every few weeks during this time to keep the plant from completely drying out. Move your hydrangea back outside only after the danger of frost has passed and resist the urge to prune until the plant has entirely leafed out. At this point, you can easily remove dead or damaged wood without inadvertently sacrificing flower buds.

Plant now and enjoy your beautiful potted hydrangea(s) for years to come!