Hydrangeas are one of the most popular shrubs around. They are highly prized for their large pastel-colored, or white flowers that provide an attractive flower display both on the shrub, and as part of cut flower arrangements. They are the subject of much garden research – soil pH, pruning, and increased blooming. Their showy flower displays are well worth all the effort – unless they’re not blooming the way they should. When your hydrangeas aren’t providing you with the blooms you want, it’s time to find out why.
Here are some tips to encourage your hydrangeas to give you maximum bloom capacity.
Sun Grow the hydrangeas in as much sun as the plant will tolerate to give you more blooms. Most hydrangeas can take full sun here in Connecticut. Sunlight is the number one key to getting a bounty of blooms on your hydrangeas, so never grow them in full or heavy shade.
Water Hydrangeas like a fair amount of water, after all, their name comes from the Greek word “Hydros” meaning water. Your hydrangeas should get a minimum of 1” of water every week. Twice a week when it’s the height of summer and really hot. Water them in the early morning, slowly and deeply. This way they have a chance to really absorb the water into their root system before the day gets hot, and the water evaporates. If it becomes stressed because of lack of water (drought stressed), the first signs they will exhibit is lack of flower production. Flower production requires a lot of energy, and energy requires water. Don’t over water them. Signs of over watering include yellowing or wilting. I know – similar signs to drought stress. A good idea is to get a soil moisture meter. It will tell you the moisture that’s in the ground. This takes the guess work right out of it. A hydrangea will droop or wilt when it’s thirsty (as will all plants) but they recover quickly after watering.
Fertilize Apply a 10-10-10 slow-release fertilizer early in the spring before the hydrangea starts to leaf out. Be sure to work it into the soil and water well. I prefer an all natural, organic fertilizer. Repeat the application after the bloom season ends.
Mulch Apply a 3” layer of mulch all around the shrub’s dripline (the outer edge of the branches) in the spring. Be careful to leave an inch or so around the base of the plant. Mounded mulch can cause rot and insect damage.
Deadhead Deadhead the hydrangeas throughout the season to encourage more blooms just as you would any other flower. Use sharp pruning shears and cut at a 45° angle being careful not to crush the stems. Prune dead flowers back to the main stem. Flowers that are left after they’re done blooming will dry and attempt to go to seed, thus ending the flowering cycle.
Pruning Here’s the tricky part. Some hydrangeas bloom on old wood (many macrophylla varieties) and need to be carefully pruned. Prune out the dead and never prune any living branches later than late summer. Prune hydrangeas that bloom on current year’s wood (Arborescens varieties) in early spring before the shrub produces new growth. Hydranges pruned back to 2” to 3” produce more blooms than those that aren’t pruned.