Mass Planting

(Note: these are NOT my photos, but from the Sunset magazine website)

Recently in the Sunset magazine blog Fresh Dirt, Sharon Cohoon wrote about mass planting (July 9, 2008) . “Here’s why landscape designers keep telling us to plant in mass,” was the headline and showed two photos of beautiful gardens with mass plantings. There’s no denying that a well designed mass planting in its prime is a sight to behold. There is certainly the drama and impact of volume, so that if you didn’t notice a plant among the rest of the beauties, this style of planting won’t let you miss it. And if you missed the key words among all the others, let me repeat. “Well designed.”

This doesn’t mean that it has to be professionally designed. It's just that not every situation will look good with mass plantings, and not any plant will work in any situation. Simply planting a lot of your favorite plant will not necessarily look good. I’m thinking about the sidewalk strips that I see that are planted with a row of scraggly hybrid tea roses (America’s favorite flower). Sure there may be a nice flower or two (or a dozen) on them, but as a garden? No.

You may end up with an industrial appearance, with rows of a single type of plant in a narrow strip. (I’m thinking about a garden planted only with Indian Hawthorn - Raphiolepis indica). Unless, of course, you want that Home Depot parking lot look. You may also end up with a shopping mall look (or worse) if planted with annuals like red bedding geraniums. It can look short on imagination. It certainly is no improvement on the “one of everything” style (which I am almost guilty of). What it says is “I didn’t know what to plant, and I really don’t care as long as it is alive and doesn’t take much care. So I just bought what was pretty at the warehouse store and filled the space.” Which isn’t so far removed from the “one of everything” mentality. By the way, a “one of everything” garden can be quite beautiful if well done. It’s called a cottage garden. Not that I’m defending what my friend David calls a “kerplunker” garden, ahem.

Another problem with large scale mass plantings is what happens if a plant dies. What happens to the design if a hole is created? Does it leave an eyesore? This depends upon the type of plant. If, for example, the mass planting is of agave planted on a grid, and one flowers (and dies), a gaping hole is left in the design. Sure you can replace it with another one, but is it the same size as the others? What if you can’t find one? Trees have this problem as well, such as in an allee when one tree dies. Plants grow. You can’t replace a 30 foot tall tree very easily.

With mass plantings, though, there are benefits other than impact. There is economy of scale. With a mass of the same plants, there is uniformity of maintenance. The irrigation is the same, trimming, clean-up, mulching, and other care can all occur at the same time. For the mass planting of feather grass, the whole thing can be mowed in the spring, which you couldn’t do if they were interspersed with shrubs. It’s like having a field of corn, which, fortunately or unfortunately, it can look like.

So, hopefully you have not been discouraged from doing a mass planting. But how do you plan for a mass planting?

Choose your plants carefully. Not all plants will work well in a mass planting. Some look their best in a mass planting. Others don’t look good in a mass planting. Some work in either situation. Imagine the first garden, a mass planting of lavender, but replaced with something else. Would it have the same character and impact if it was planted with Perovskia atriplicifolia (Russian sage)? I think not. The irregular spiky outline of Russian sage would not only make the planting look messy, but would also interfere with the contrast between the upright cypress and olive trees and the rounded shapes of the lavender. Although lavender would be the obvious choice for this mediterranean-style garden in a vineyard, other options would be of similar form. Convolvolus cneorum comes to mind, with silky leaves which flash silver when the wind blows and white morning-glory flowers. Cistus x cobariensis would be a good option also. Culinary sage would have similar stature and would bloom a similar color, on a coarser textured plant and a different fragrance.

The key is that these plants would be chosen for their form as it relates to the whole design. They would also be chosen for their year-round attractiveness. Keep in mind that with a mass planting, while the impact is impressive during peak season, the same goes for the down season. And with larger scale, bad ideas are bigger and more expensive to replace. This doesn’t mean you have to use only backbone plants (what I call plants that don’t change much from season to season like holly). But imagine again, that first garden planted with peonies instead of lavender. Their forms would be similar, it would be terribly dramatic when in bloom, and still attractive through summer. In the winter, the ground would be bare. Maybe not the effect you’d desire, unless the garden were not the main garden and could be visited primarily at peak. For with a mass planting such as this, when the season is over, it’s over. I love bearded iris gardens, but I don’t want to look at withering foliage most of the year in order to have that glorious month. At what season do you want the garden to have maximum impact?

Which goes to say (obviously) that these types of gardens are not for plant collectors. Although I dream of having a garden such as this, the reality is that it would only work if it were my second home (yes, this is dreaming).

There’s nothing to follow up the main show except the form and structure of the garden. Notice that the lavender garden has nice form even when the lavender is not in bloom. There is the gentle curve, the varying heights of interest in the olive trees and cypress as well as their varying forms. But not too much. In the second photo, if the grasses are gone, the interest is carried primarily by the house with trees and the sculpture. When the grasses are trimmed in the spring, the garden would look like just about any other suburban house.

What plants work best with mass plantings? It depends on the situation. For gardens such as these, where the garden is designed around one plant, the choice must be carefully made. As I said before, there should be four-season interest. Plants need to have uniform size, form, and structure (seedlings may have variability), but not so much that they look industrial. Look to the gardens of Piet Oudolf or Oehme & Van Sweden for examples. There’s a reason why they have their signature plants (such as ‘Goldstrum’ rudbeckia with ‘Autumn Joy’ sedum and miscanthus).

More on plant choices later. Feel free to contribute your choices.