For those of us who adore hydrangeas, New England can be a tricky place to grow many varieties and enjoy their beautiful blooms. One of the most frequent questions we hear is "Why didn't my hydrangeas bloom this year?" There are several answers for that question, and I will try to help you understand the possibilities, along with giving you some tips on growing healthy plants.
If the winter was too harsh, the temperatures too low, and your hydrangea died back to the ground, you won't get blooms, as most varieties bloom on old wood (except 'Endless Summer'). Better luck next year! If your plant always freezes back, remove and plant a hardier variety (try Arborescens, Paniculata or Anomola varieties) or try to protect it from the winter winds and hard frosts with burlap, a cage with leaves, or planting it in a protected spot. Also, protect the tender new spring buds and leaves from frost, as these contain your new flowers! Unseasonably low temperatures after a mild winter also cause a lack of blooming.
Improper pruning is the most common reason why macrophylla (mophead and lacecap) hydrangeas don't bloom. You may have pruned either too late or too much. Prune either in the fall after bloom (Sept. is best here), or in the spring after the hard frosts are over. The later and the more drastically you prune, the fewer blooms you'll have! Prune only to the first leaf node of this year's growth, cutting 1/2" to 1" above the budding node at a 45-degree angle. These buds will be the new leaves and blooms of your hydrangea. Protect these buds from spring frosts with bedsheets or frost cloth! Also, remove up to a dozen of the inner, old woody branches on established plants. Cut these to the ground to spur new growth at the base. You can also shape new plants when you put them in.
Too much fertilizer can stunt your blooms. Too much nitrogen and you get a healthy plant with beautiful foliage, but no blooms. Apply a balanced granular time-release 10-10-10 fertilizer to slightly moist soil just two times a year - early spring and early fall is fine. For blue blooms, add aluminum sulfate. To increase the red and pink colors, raise the pH with lime. The best pH is 4.5 to 6.5.
Poor soil could also be the problem causing no or few blooms. Amend the soil as needed with compost, potting-mix, peat moss, or perlite--but be careful that you don't add too much nitrogen, which will produce lots of beautiful foliage but no flowers. Compacted soil needs amending with good well-composted material. Pay attention to the salt and nitrogen content of manures and homemade mixes. Check your pH! Clay soil comes in different types also. Break down salty clay with gypsum, and a mineral amendment that replaces salt with calcium. Be sure to amend the soil three or four times the size of the anticipated root ball. Hydrangeas need lots of room for their roots to grow.
Or perhaps your plant did not get enough water. I noticed that my 'Endless Summer' often wilts in the mid-afternoon sun and it produced only 5 blooms total last summer. My sandy subsoil is probably not retaining enough moisture, either. Do a drainage test: dig 6" deep by 1' wide, fill with water and let drain, refill, and if it drains in 3 hours, or takes more than eight hours, you have a problem. It should drain in 4-6 hours. Also check for too much compaction: a quarter-inch gauge wire should bend only after going down a foot. Your soil should clump in small but breakable consistencies. You can add grass clippings, leaves, compost, manure, or other amendments.
A few hours of sun is perfect. It is best to protect hydrangeas from hot, afternoon sun. New plants need some protection. I have seen 'Endless Summer' recommended for part-shade locations.
Slugs, snails, deer, thrips and spittlebugs, powdery mildew, black spot, and rust are the most common problems on hydrangeas. Water them only in early morning to keep their leaves dry. To control predators, use natural remedies if at all possible.
You should only transplant established plants or divide the root ball in the spring AFTER your last frost date (early June for most of us here). Never move your bushes when the temperature is under 40 degrees or over 85 degrees. Leave the root ball 1" above the original soil level. You don't want water to stand around the plant in a depression. But you do want to water your new plants thoroughly and keep them moist in hot weather until they are established.
I hope these suggestions will help you enjoy beautiful hydrangeas for years to come! You can, of course, get more information on the web. I especially thank Kristin VanHoose of Hydrangeas Plus for helping me learn more about caring for hydrangeas.
For an excellent newsletter on hydrangeas, go to: www.hydrangeasplus.com