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WHY WON'T MY HYDRANGEA FLOWER?
Getting them to bloom in your yard!
The key to successfully getting your Hydrangeas to flower is understanding how and where they produce their flower buds. Hydrangeas come in a multitude of species and varieties, and all we basically need to know is . . . Group 1: Some species bloom on new growth (current new growth). Panicle Hydrangea( H. paniculata), and, Annabelle Hydrangea (H. arborescens), all flower on this year’s new growth.
These species
bloom reliably each year and require no special care to produce flowers.
Group 2: Some species bloom on old growth (last years stems) French Hydrangea or Bigleaf Hydrangea (Hydrangea macrophylla) and Serrate Hydrangea (Hydrangea serrata-These species typically have colorful flowers (blue, pink, red-pink, lavender, or white etc.,) that are either large balls (mopheads) or flat and lacy (lacecaps) Oakleaf Hydrangea (H. quercifolia) Climbing Hydrangea (H. anomala)
The real challenge ... is consistently producing flowers on varieties that bloom on last year’s stems, Group 2 plants (H. macrophylla and Hydrangea serrata.) Although, hardy enough to survive in zone 5 and into zone 4, their flower buds are prone to damage either by an early frost on autumn, a late frost in spring or excessively cold temperatures when dormant in winter. This, along with untimely pruning, can result in inconsistent flowering or no flowering at all. SOLUTIONS For growing Hydrangea macrophylla and Hydrangea macrophylla var. serrata types in zones 4 and 5. The following solutions have been tested successfully in Michigan and Maine’s northern interior since 1993.
Don't
prune
unless necessary. Pruning often
removes the flower buds. If you need to prune, remove any dead stems in
the spring. Any other necessary pruning should take place immediately
after bloom. The new flower buds form in autumn, when night temperatures
consistently drop below 60 degrees.
Cover the plants to
a depth of at least 12-18 inches with mulch, bark, oak leaves, pine
needles, or straw. Cover the entire plant,
tips included, if possible. Remember not to use maple leaves
because they will mat when wet and can suffocate the plant. Some people
make cages out of snow fence or chicken wire to hold the mulch. One
creative gentleman, who every year has a spectacular Hydrangea garden,
uses 20 gallon plastic trash cans. He cuts off the bottoms, places them
over his plants in early winter, fills them with mulch and then puts the
lid on them until spring. . Remove the mulch only after any major threat of frost (50% frost-free date) has passed. For the Mid-West Michigan that is around May 15th. Do not be concerned if there are small white leaves and stems they will survive and turn green again quickly. If this is too much work - then consider growing the first group of Hydrangeas listed above. CULTURAL TIP For many plants in group 2 the flower color is determined by the soil pH. This is particularly true of the blue and pink colored varieties. A low pH (acid soil)) results in = blue flowers, a high pH (basic or alkaline soil) results in = pink flowers. pH can be lowered using Aluminum sulfate, or sulfur, and it can be raised with dolomitic lime. Consult your nurseryman for details and rates. Interested in learning more about Hydrangea then click here. If you would like to see an extensive list of Hydrangea cultivars and descriptions then click here.
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