Revamp your perennial gardens: height, color & more

by Connie Oswald Stofko

A new trend–but not a good one– is gardeners asking for very small plants for perennial beds, said Jen Weber, vice president and manager of Mike Weber Greenhouses, 42 French Rd., West Seneca.

“They come in and want plants that are four inches high or smaller,” she said. “From a distance, a four-inch plant disappears. Every single day I have to explain. It makes me shake my head all the time.”

Could it be that the plants in your perennial garden are too small? If your garden isn’t quite what you’d like it to be, check out these tips on how to revamp it.

What is a perennial?

A perennial is a plant that comes back more than one year. Gardeners often think of them as plants that come back every year.

Biennials are usually treated as a subset of perennials. In the first year, biennials won’t flower. In the second year, the biennial will flower, go to seed, then die.

There are some true perennial plants that can’t withstand Western New York’s cold winter. Gardeners here call them annuals and treat them as annuals–you have to plant them every year.

Planting and transplanting perennials

Even when the weather is hot, you can transplant a perennial from another part of your garden or from a container you bought at a garden center. The heat isn’t what you have to worry about; it’s water that’s a concern.

“You just have to water the plant,” Weber said. “Water it in the morning before you move it. Then move it in the afternoon and water it after you replant it.”

Wrong height

Problem: Plants are too small

Some basic advice for gardeners is to plant tall plants in the back, medium-sized plants in the middle and short plants in front.

But how short is too short?

“The smallest I would use for the front border is a plant around eight inches tall,” Weber said. One example is a dwarf betony or Stachys minor, which is in bloom now.

“You want your plantings to be tall enough to be seen,” she said, “especially if they’re not in bloom.”

For the middle and back, “You want feet, you don’t want inches,” she said. Plants should be at least two feet tall for the middle and four feet tall for the back.

Some tall perennials that are blooming now or will bloom soon are mallow and hollyhocks (three feet tall), delphinium (varieties range from three to six feet tall), oriental lilies (can get more than four feet tall, depending on sun conditions) and hybrid coneflower or Rudbeckia ‘Autumn Sun’ (seven feet tall).

So how can you use smaller perennials? Weber pointed to ‘Chocolate Ball’ and a ‘Lemon Ball’ sedums. Those lovely sedums would work well in an area where everything is low, such as a rock garden or a slope, she said.

Problem: Everything in your garden is the same height

When every plant is the same height, it’s simply boring. That’s why gardeners hear advice about tall, medium and short plants. Mix it up.

Take a look at the photo labeled “Mistakes!” Part of the problem with that arrangement is that the bulk of the plants are about the same size. The “Better” photo has a variety of sizes.

Problem: Heights aren’t balanced

Another problem with the photo labeled “Mistakes!” is that there is a drastic difference in height between the medium plants and the tall delphinium. In the “Better!” photo, there isn’t a big jump between the heights of the plants; the heights descend gradually, bringing your eye down. (The shortest plant, dwarf betony or Stachys minor, looks a bit too short in comparison to the other plants because the other plants are in larger pots. It would look more balanced in your garden.)

You can even use all “tall” perennials in a grouping, Weber said, if there are differences in height among the plants. For example, you could group a hydrangea ‘Limelight’ that gets seven feet tall, a butterfly bush ‘Miss Molly’ that gets five feet tall, ninebark that gets three to four feet tall and ornamental grasses such as ‘Dallas Blues’ and ‘Standing Ovation’ that get three or four feet when they flower. You don’t need to use smaller plants.

Problem: Rigid rows

When people try to follow the advice about tall in back, medium in middle and short in front, they can end up with horizontal rows with the same heights, left to right, and plants stacked from front to back.

“You don’t have to use just three heights and they don’t have to be in a line,” Weber said.

Instead, she said, think about planting in clumps. It’s a different way to design your layout. Take a look at the “Better!” photo. The grouping is cohesive in height and color. You don’t have to stack the four plants one in front of the other. In your garden, you might use a few more specimens of these plants to make it fuller.

Poor color choices

Many people like pink flowers and purple flowers, which you can see in the “Mistakes!” photo, but putting only those colors together doesn’t provide enough contrast, she said. She recommended adding yellow, which you can see in the “Better!” photo.

Orange is another choice for contrast, but many gardeners say they don’t like orange. Weber suggested trying coral colors, such as the rose in the first photo.

Perennial is in the wrong spot

The spot might be too shady, sunny, wet or dry for the plant. A tall perennial in front may be obscuring a smaller plant. It’s your favorite plant but you can’t see it from your patio.

If it’s not a good spot, move the plant.

Perennials are overgrown

A perennial is overgrown if it is too big for the spot it’s in. You can move the whole plant to a larger spot or dig out part of the plant and move just part of the plant.

Nothing is in bloom

You probably shopped at the beginning of the season and bought plants that caught your eye– ones that were already in flower.

Go to a garden center now to see what is in bloom. And while you’re there, find out what perennials will be the next to bloom. And look ahead to what will bloom in autumn.

You have a plant you just hate

Sometimes you choose a plant and you don’t like it as much as you thought you would. You might even hate it. You are allowed to remove the perennial from your garden.

It doesn’t make you a bad person or a bad gardener.

“I’ve done that, too,” Weber said.