Those Other Hydrangeas

hydrangea Annabelle (7)My previous post about hydrangeas was narrow in scope.  Annabelle hydrangeas, or hydrangea arborescens “Annabelle” are commonly known as smooth hydrangeas. Their giant spherical flower heads are identifiable from a block away.  They have an annoying tendency to flop over.  Like peonies, their giant flower heads can topple an entire stem in a strong storm. That aside, they are showy. They bloom on new wood. Most encouraging of all for gardeners in my zone? They are both plant and bud hardy to zone 3.

limelight hydrangea hedgeLimelight hydrangea, or hydrangea paniculata “Limelight” is  hardy to zone 4.  The flowers are cone shaped.  The stems are incredibly strong, and upright. The flowers are not truly white-they are a lime green verging on white. They also bloom on new wood.  This means the flowers are set on the current year’s growth. A bad winter will not impact the flowering. The 4-5 foot version, Little Lime, is just as strong and hardy as Limelight.  The diminutive Limelight cousin,  “Bobo”,  grows 2 to 3 feet tall-and is entirely hardy.

all summer beauty hydrangeaThis said, I have had lots of clients express an interest in pink, or blue hydrangeas. Can you hear me sighing?  The All summer Beauty hydrangeas, both in ground and about to be planted,that you see above, is known as a mophead hydrangea. As in hydrangea macrophylla. The mophead hydrangeas are most easily grown in zone 6- 8. Truly. It is easy to see in the above picture that my client’s “All Summer Beauty” hydrangeas died all the way back to the ground as a result of our very cold winter. Hydrangea macrophylla blooms on old wood.  In early May, I could see that these hydrangeas had no live wood above ground, meaning there would be no June bloom on them. It would be a green summer for these hydrangeas- unless the plants would throw a few blooms on the new wood.

endlesssummerShocking this zone 6-8 business. All Summer Beauty hydrangea was introduced with great fanfare. They bloom on the previous year’s wood, but they also bloom on the current year’s wood. This was good news for hydrangea growers in northern climates. We had hopes that pink and blue hydrangeas would work for us.  I find that the bloom on new wood is sparse at best. The heavy bloom is the June bloom.

hydrangea_articleThe reality of the mopheads is that they promise a lot, and deliver not so much. Success with them is varied.  It is not so easy to figure what conditions will produce reliable blooming.The majority of the June  bloom resides in the previous year’s wood – wood that needs to  survive the winter. If you are growing All Summer Beauty, do not prune in the fall. A fall pruning removes flower buds.  Site your mopheads out of the way of the wind.  If you are mophead driven, be prepared to protect your plants over the winter.

July 13, 2012 035I do have a number of clients in Grosse Pointe.  This is a metropolitan Detroit community situated along Lake St. Clair. The mopheads I see on the west side are great once in a great while.  In this community, I see pink and blue hydrangeas blooming profusely every year.  I can only surmise that the water is a mitigating circumstance.  Water side gardens cool off  very slowly in the fall.  Plants enter the dormant stage slowly.  A big lake is slow to warm up in the spring, and protects garden plants from precipitous drops in spring temperatures.  A lake nearby is a blanket, both fall and spring. The big lake side gardens are most surely a zone 6 – maybe warmer. This is my guess.

blue hydrangeas
I have one client whose stand of mophead hydrangeas are gorgeous every year. Only one, I might add.  I really have no idea why they bloom so beautifully. I was advised that this cultivar is Nikko Blue, but this information is anecdotal.  I did not plant these. They were in place when I came to work for her. They are reliable in bloom, every year.  My other clients with mopheads have lots of green years, punctuated by flowering years now and then.  Some repeated successes I ascribe to a serious program of winter protection.

[wallcoo]_hydrangea_picture_4(1)I will say I have never seen hydrangeas other than white bloom like this.  If you have a big love for hydrangeas, research any plant you have a mind to purchase.  You need to know what species of hydrangea is the parent, and how to properly prune it. You need to cast a critical eye towards that place you plan to site them.  Is it near a house wall? Is the intended planting in a windy and exposed location?

July 13, 2012 039When a mophead hydrangea is happy, it is very very happy.

FullSizeRenderA good client emailed me this picture yesterday.  He saw these hydrangeas in bloom in Rhode Island.  Could he grow them in his garden?  This is a lace cap hydrangea which like the mophead, is hydrangea macrophylla.  It will suffer from bud loss from spring frosts, a too late pruning and a too cold winter in the same way as the mopheads. As beautiful as they are, they will not reliably like being planted in a Michigan garden. If they are killed back to the ground over the winter, they can come back-but the bloom will be very sparse. I doubt my client would have much luck with these.

hydrangeas Aug 15 2013 (17)I do not have much experience with hydrangeas other than white. I have a preference for hydrangeas that wholeheartedly like my zone. Were I dead set on having them, I would experiment to see what location in the garden was the most friendly to good flowering.  Some of the newer varieties may be more hardy for you than others. There are so many varieties available to choose from.  Perhaps there is one that will work in your garden.

Heavenly Hydrangeas

What is it about hydrangeas that makes them such a magnet for gardeners?  No doubt they are one of the showiest shrubs hardy in my zone.  They are fairly easy to care for, providing you stay away from marginally hardy varieties.  They grow fast, have big, clean, and very green foliage.  The massive flower heads speak to summer.  What could be better?  The plant hybridizing industry has focused on producing more reliably blooming “other than white” hydrangeas for the nursery trade geared to produce in cooler climates.  This “All Summer Beauty” hydrangea is more reliably blooming than its predecessors.   

The Annabelle hydrangea has been the mainstay of the summer shrub garden as long as I can remember, though I no longer plant it. Weak stems and overly large flower heads make the shrub a challenge to keep off the ground.  Given heavy rains and mid summer stormy weather, you are likely to wake up with those flowering spheres face down in the mud.  Should you have them, cage or otherwise securely stake at least 40″ tall out of the ground-in the spring.  Othereise, you will be chasing some stop the flopping solution that looks awkward and unnatural.   

This garden no doubt is the one place for 100 miles perfectly suited for Nikko Blue hydrangeas.  Once out of the nursery pot, and in the ground, they are generally known to be stingy with the flowers.  Blue hydrangeas-what midwestern gardener does not long for this plant to perform for them?  I am sure many more get sold, than deliver and please.  As no one grows hydrangeas for their shape and foliage, choose a cultivar known to reliably produce flowers in abundance in your zone. 

Flowers in abundance-perhaps this is what makes hydrangeas so attractive in a landscape.  I favor the Dutch hybrid-known as Limelight.  They are sturdy growers-there is never any need for staking.  Their hydrangea paniculata parentage is responsible for the cone shaped flowers that open green, mature white, and pink with age. The straight species hydrangea paniculata is a very wide and very tall grower.  The flowers are many, but modest, open and subtle in appearance. A hedge of panuiculata 8 feet wide by 40 feet long might make a show.  Limelight produces densely showy flower heads from a vigorous and adaptable shrub-the best of all worlds, should you be talking hydrangeas. 

Densely blooming and showy-see what I mean?  They do not ask for much-this part I am especially fond of.  They handle full sun, given sufficient water, with aplomb.  They will willingly survive part shade, and bloom better than most hydrangeas starved for sun. They grow fast.  They are fine with a serious spring pruning.  I have Limelights I prune down to within 14″ of grade-where it is my idea to keep them in the 4′-5′ tall range.   

Given a space of sufficient size, a hedge of hydrangeas provide no end of a robust visual reference to summer, lots of flowers for bouquets, screening, material for dried arrangements.  What garden shrub do you know of that delivers on this scale, and to this extent?   

Should you be thinking you might plant some limelights, I would make the following suggestions.  Locate them in as much sun as you can muster.  Do not space them any closer than 30″ on center-36″-42″ on center will fill in in no time.  They like regular moisture.  Whatever you have done to enrich your soil with compost, the hydrangeas will appreciate.  Given how fast they grow, a 3 gallon plant will catch up to a five gallon plant in no time at all.  If you plant smaller plants, be sure they get regular water to the rootball.  Potted hydrangeas become rootbound in the blink of an eye.  Lacking the water they need, the foliage will burn and drop-this is not a good look.

My landscape features 2 large blocks of Limelight hydrangeas-25 plants in each block. They are about 7 feet tall, and just coming into bloom.  In full bloom, they are glorious. In late bloom, they are beautifully moody-green, white, and white speckled with rose pink.  The show goes on for a number of months.  The limelights are just now coming on-I am ready.