Flashy hydrangeas can grow just fine in Alaska gardens

Last year I attended a summer conference in Minnesota. We toured some really huge commercial facilities, greenhouses, propagation rooms and associated potting and shipping areas. It was really, really hot in that Minnesotan way, and we were shown a ton of hydrangea plants. There were so many that I wondered who could possibly be buying them all.

Did I mention it was really hot? This Alaskan had a really hard time concentrating, but I think I heard someone say hydrangeas were the most popular summer plants by far. Obviously, not in Alaska.

It is time to change that. There are, to be sure, two categories of hydrangeas that do perfectly well in Zone 3-4-5 (which is how I describe the zone in which most Alaskans live). One group is hydrangea arborescens (the smooth hydrangeas). The other, hydrangea paniculata, includes what is known as panicle hydrangeas. Both have flowers that consist of florets bunched together to form a shape. Some can be as big as a football.

Let’s start with the arborescens. These shrub plants grow to 4 or 5 feet, not as large as many hydrangeas. They do bear similar flower heads, though depending on breeding they may be only dome-shaped instead of completely round.

Flowers are usually green when they start and then mature to a light green we don’t often see in our flower palette. There are white varieties, and the facilities I visited last summer have apparently developed a pink flower.

Though these will develop into nice, bushy shrubs, the great feature of these plants for Alaskans is that they bloom on new wood. This means you can completely mow or cut your plants down in the fall if you want. This also means you can plant in areas where snow piles would kill or damage a normal hedge.

Paniculata florets form a panicle. They start out white but mature into different colors, mostly pink and red hues. Hydrangea paniculata has the same “new wood” characteristic. Both, however, get larger If you don’t cut them down in the fall. You should be able to get a bushier plant over the years. If you need to trim, take off some of the old wood.

Neither of these two categories of hydrangeas needs special soil. However, they do need good drainage. In fact, they are not fussy and may even react poorly to too much fertilizer and water. They do need four or five hours of sunlight.

You can often find both of these types of hydrangeas locally at nurseries and box store plant areas. One reason is that both do well in containers and make great deck plants. You can also order via the internet. There are lots of places to check out.

Finally, when I was 6 or 7 years old, my father taught me that the secret to changing pink hydrangeas to blue was the soil’s pH. It all has to do with the ability of a plant to use aluminum. Who knows, that lesson might just have been the demonstration that sparked my deep interest in soil science. However, the two Alaska varieties don’t act the same way and you cannot pull off this trick.

Jeff’s Alaska Garden Calendar:

Alaska Botanical Garden: Plant sales from the nursery through Sept. 15. Check out www.alaskabg.org for a complete listing of classes and events, and even what is blooming.

Alaska Master Gardeners of Anchorage: Fall plant sale Aug. 10 from 10 a.m.-3 p.m. in the parking lot of Benny Benson school next to ABG.

Lawns: Pattern time. Why stick with the same old same old? Put in some circles, stripes and diagonals.