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New & Exciting Panicle Hydrangeas

May 14, 2018

Written by Dave G.

If you have gardened in colder parts of the country for a long time, you will remember the ubiquitous PG Hydrangea, still seen in many gardens. It’s a standard shrub for later flowering – reliable, hardy, but with several faults that make it a long way short of perfect. To begin with, it grows quite large – older plants that have not been regularly pruned can be the size of a small tree. Secondly, the promise of those big blooms is often lost when they sag over, in a very droopy, sad fashion. As well, although they turn pinkish in fall, they are basically white – which is a useful color, but in the end can be a bit boring all summer long.

After decades of being stuck with that one plant if you wanted to grow hydrangea in colder zones, things began to improve with the arrival of the Limelight Hydrangea, which held its heads up much better, and had interesting lime-green tones in the flower, especially as they developed. This is still a large shrub, so the arrival of the Little Lime Hydrangea was welcomed by gardeners with smaller gardens.  This beautiful shrub has the same lime green tones in its flowers, but it grows only 3 to 5 feet tall. It works perfectly in a smaller garden, as a foreground shrub in a larger bed, or even in a large container, where it looks just great outside a door or on a terrace.

That pink fall coloring of the old PG Hydrangea was tempting to plant breeders, who set about enriching it, and bringing it further forward in the season – not just a fall treat, but a summer highlight. The best of the new plants featuring this enriched coloring is the Firelight® Hydrangea, which develops huge flower heads, up to 16 inches long. These hold up well, and turn pink in summer, well before other varieties. By fall they are a rich burgundy, really lighting up the garden and putting on a terrific show before the cold arrives. Firelight is the product of the breeding work of one of the top breeders in America, Timothy D. Wood, who works out of Spring Lake, Michigan. Although the flower heads are large, the plant itself is a much more manageable 4 to 6 feet tall.

Besides Americans, Europeans too have been working with the panicle hydrangea, and a terrific plant from Belgium in the Little Lamb Hydrangea, created by Jelena DeBelder. She is a passionate hydrangea breeder, and this was her personal favorite. Besides its smaller size, growing just 4 to 6 feet tall, the significant difference is in the flower size. The flower heads are just as large as other panicle hydrangeas, but the individual flowers in them are much smaller, and more profuse. This creates a fluffy, more feminine look, and a bush that looks like it has a flock of lambs gamboling across it. These are terrific beside a pathway or terrace, and it grows well in a container too. A pink blush begins to spread over the flowers as soon as the cooler nights of late summer arrive, and by fall they are a rich, deep pink, bringing plenty of interest to your garden.

If these 5 to 6-foot tall plants are still a bit big for you, then consider planting one of several even smaller plants that have become available. The Bobo® Hydrangea stays at or below 3 feet tall, the perfect size for a smaller spot, a smaller garden, or a planter box. Despite its small size, the flowers spikes are 8 to 10 inches long, and the fall colors of reddish purple are especially rich.

Another smaller panicle hydrangea that is catching on is the Little Quick Fire® Hydrangea. One criticism of the smaller panicle hydrangeas is that the large panicles look out of proportion, and too big. Little Quick Fire solves that with smaller heads, looking more in proportion on the 3-foot plant it grows into. It can grow taller if pruned very lightly, but never more than 5 feet. This plant is especially useful in colder areas with short growing seasons, because as the name suggests it is quick off the mark, and it is in bloom about a month earlier than other varieties. This doesn’t mean it is over sooner too – no, it keeps going through fall, just like all the rest. By then it too will have taken on pinkish-purple tones, and it looks great in any smaller space, or mass planted in a larger one.

If you are nostalgic for the old PG Hydrangea, then there is a new replacement that eliminates those droopy weak stems, but otherwise is almost identical. This is the Phantom Hydrangea, a dead-ringer for a PG, but with sturdy stems that keep those enormous panicles upright right to the very end of the season. It will grow 6 to 8 feet tall, or even more, and it is perfect when you have a larger space to fill, and the location needs that extra height. The prestigious Royal Horticultural Society was so impressed with this plant that it took away the Award of Merit given the PG Hydrangea in 1993, and gave it instead to the Phantom Hydrangea, in 2008.

Tips on Growing Panicle Hydrangeas

If you are going to grow one or more of these newer forms, then you want to do it right. Noted for being hardy all through zone 3, these plants are also favorites in much warmer areas, where mop-head hydrangeas will also grow, because the panicle hydrangeas are much easier and more reliable. They take full sun or partial shade, preferring a bit of afternoon shade in hotter zones. They grow in almost any kind of soil too, just as long as it is not constantly wet. They are more drought-resistant than mop-heads are, which is another great advantage.

Pruning is the main job they need. Just once a year, but worth the little time it takes. There are three possible pruning methods, and each one has merit – it depends on what you want. Prune in late winter or early spring. Some gardeners like to wait for the buds to begin to sprout – it makes it easier to see where to cut to if you are a little inexperienced.

  1. Light pruning. This is simply a matter of removing the old flower heads back to the first pair of healthy buds. Take out any broken branches, and any very weak ones, but otherwise leave things pretty much alone. Plants pruned this way will have the greatest number of flower heads, but they will be noticeably smaller in size. This is a good technique for an informal style of garden.
  2. Medium pruning. Here you cut back the old flowering stems to leave four pairs of buds on the part of the stem that sprouted the spring before. This will be apparent from the change in bark color. Again, remove any weak or damaged branches, and on older plants a couple of the oldest branches completely, so that things don’t get too crowded. You will still get plenty of flowers with this technique, and they will be noticeably larger.
  3. Hard pruning. If you want the biggest heads, on the longest stems, and are prepared to sacrifice quantity for quality, then this is the pruning technique to choose. Cut back to leave just two pairs of buds on each stem. As well, remove any weak shoots or over-crowded ones.

 

With the old PG Hydrangea hard pruning often failed because the long stems that resulted were too weak. That won’t happen with the newer varieties, and you can enjoy those huge heads – especially nice when dried and placed in vases around the house in winter.

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