Twig Tips by Jodie

Posted on July 30, 2016 by jo

Those Darn Hydrangeas!!!

Those darn hydrangeas, why won't they bloom?  Why aren't they blue?  Why, why, why....Hydrangeas seem to confuse the heck out of many of my customers.  There are too many varieties of 4 main species that grow in our neck of the woods.  Some of them are great, some of them are worthless.  I'm going to try to 'splain which ones are which so that you don't waste your time and money on the duds.

1) Hydrangea quercifolia,  Oakleaf Hydrangea.  These beauties are easy to grow, very hardy, like sun or partial shade, have GREAT fall color and conical blooms that start out white and darken to a rose-pink.  They can get some size, mine at home is about 6' wide and 5' tall.  These bloom on the OLD growth so don't prune them hard in the spring, you will lose your blooms.  Minimal pruning is best so just leave them some room to grow.

2) Hydrangea arborescens, Smooth Hydrangea.  The most well-known variety of this one is called Annabelle.  These are the ones with the BIG white balls and will never turn pink no matter what you do so give up on that idea.  They do have a pink one now called 'Invincibelle Spirit' so if you want pink, get that one (BTW, every purchase donates some $ toward breast cancer research). They tolerate a lot of shade and get about 5' wide and 4' tall.  Annabelles are very hardy and bloom on new or old growth so pruning hard in the spring will not affect the blooms for that season.

3) Hydrangea paniculata, Panicle Hydrangea.  These can be AWESOME landscape plants, very dependable and adaptable.  Familiar varieties might be Limelight, Pink Diamond and Grandiflora (also known as P.G.)  They can get some size and can be trained into dwarf trees. There are some newer dwarf varieties that stay smaller and we are crazy about them (Little Lime, Strawberry Sundae, and Little Quickfire to name a few) They, too. bloom on the current year's growth so whack away late in the fall or early in the spring, doesn't matter.


4) Hydrangea macrophylla, Bigleaf Hydrangea.  This hydrangea is the one that just befuddles people.  They are the ones that turn blue or pink depending upon soil acidity and aluminum availability.  These are also the ones that NEVER bloom here in northern Indiana UNLESS they are one of the new cultivars like Endless Summer.  Why don't they bloom?  Because they set buds on the previous year's growth and then promptly die back to the ground during our winters, thus killing bloom buds.  The tops will come back and be very pretty but who wants a hydrangea with no blooms?  Not me.  So until global warming changes our current temperate zone from 5 to 6, make sure that you get one of the new cultivars of this species that bloom on the old OR the new growth.  We treat these dudes like perennials, so don't worry if they die back, they will come back and bloom.  We usually trim them in the spring after they bud so we can see how far to cut them back.  And if you want them to be blue, the soil needs to be acidic to make the aluminum available to the plants and then adding more aluminum sulfate will help.  Click here to read more about this.

Hope this clears things up and answers some questions for you about a lovely landscape plant that no garden should be without.

Off to hug my big Oakleaf Hydrangea because I LOVE it!   - Jodie

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