Get Your Edge On: How To Nail Down The Perfect Edging Plants

Finding reliable edging plants is like digging for gold - hard to come by but well worth the effort. They're the glue that make or break a planting. If you spend the time on this part, the rest is a piece of cake. A tidy attractive border makes a bed look appealing even if the rest of it isn't perfect. 

 A recent request for advice from a reader got me going on this rant. Here's a photo of the front of her house. "A boring planting that was supposed to be low maintenance, she says, but to me it just looks like a jumbled up mess. Others say it doesn't look bad but it messes with my head." 

 I can see why. Maybe the shrubs are boring, but the real problem is the front border. My eye goes right to the leggy cosmos on the left and the spotty splashes of annuals in front of them. Without doing a whole rehab of the bed, an easy fix would be to plant an edging that didn't look so unkempt.

Like what you may ask? There's no simple answer to what the best edging plants are - it depends on the style and size of the bed, exposure,soil type and color scheme. They can be perennial, annual or even low growing shrubs. Ideally, they should behave, look pretty all summer and not be too demanding. Whew! That's a tall order that requires a good bit of consideration. For right now, let’s stick with annuals and perennials.

1. Size and growth habit:

Forget plants that have leggy or sprawling growth habits. Look for tidy mounders or spreaders with foliage that won't look ratty by the end of summer. Anything that flowers should need minimal to zero deadheading. Look for plants with a height range of a foot or under for small beds, one to two feet for a larger one. Pay attention to how much horizontal space they require. Something short in height (about 10-12") like the Calamintha nepetoides 'White Cloud' is okay for a small bed if you want only one type of perennial in the border, but they don't play well with others because they spread quickly and crowd out anything planted next to them.

Calamintha nepetoides 'White Cloud'

Small Perennial Edgings/Sun:

I'm big on short varieties (1-2') that don't eat up the whole border. Here are several that work well:

• Germander 'Upright'

• Dianthus 'Firewitch'

• Nepeta 'Kit Kat' 

• Alium ‘Millenium’

Dianthus 'Firewitch' on the left - the photo was taken in late October. It's a tidy little gem with dark pink flowers and attractive silver foliage.

Larger beds can handle spreading perennials like Nepeta x faasenii 'Blue Wonder.' This variety gets points for airy gray foliage and long lasting blue flowers, but will quickly encroach on anything next to it.

Nepeta x faasenii 'Blue Wonder'

Geranium 'Rozanne' is a spreader but an excellent edger if you have the space. It starts blooming in July and lasts late into the fall. I took this photo the other day and it's still going strong.

Geranium 'Rozanne'

 Large Perennial Edgings/Sun:

If you have enough room, here are several that will do the job:

• Coreopsis 'Mercury Rising' (not too much of a spreader)

• Geranium 'Rozanne' (needs room to spread)

• Hemerocallis 'Happy Returns' (stays in place-blooms twice if you deadhead)

• Sedum 'Cauticolum' (mounds stay neat) 

Mixing Edging Plants:

A border doesn't have to be all the same plant, but it shouldn't look busy. If you decide to mix varieties, mass the same plants in blocks of 5 or more and repeat throughout the border. Combining perennials and annuals is another option for continual color.

Shady Edges:

Here's an example. Below, Carex flacca 'Blue Zinger', Plectranthus 'Mona Lavender' and Heuchera 'Silver Scrolls' provide a subtle mix of texture, foliage and color that lasts all summer.

Love that little zing of purple in the heuchera at the bottom of the above photo! Hostas and heucheras are easy, dependable and attractive choices for a shady border.

 Shade Perennial Edgings:

• Alchimella mollis (Lady's Mantle)

• Athyrium nipponicum (Japanese painted fern)

• Brunnera 'Jack Frost'

• Heuchera all varieties

• Hakonochloa (Hakon grass)

• Hosta - shorter varieties

• Carex varieties

2. Flowers and Foliage:

Edging plants should suit the style of your bed (formal, informal) and enhance the perennials or shubs behind them. A border doesn't necessarily have to flower. In the photo below, softly textured  Liriope foliage accentuates a formal line of boxwood.

Stachys 'Helen Von Stein' (big gray leaves to the right) doesn't blossom, but that bold foliage makes a strong statement. The smaller flowers of Geranium sanguineum 'Lancastriense' and Calamintha nepetoides 'White Cloud' stand out against it.

Left to right: Geranium sanguineum 'Lancastriense' and Stachys 'Helen Von Stein',Calamintha nepetoides 'White Cloud' at the top.

A word about vantage point - if you're viewing the bed from a distance, large masses of bold foliage and flowers show up best.

Tiny flowers and delicate foliage are more effective at close range.

 3. Annual or Perennial?

There are many advantages to using annuals as an edging. You can't beat them for summer color and there are plenty of choices. You can change the color scheme every year. On the down side, you have to keep replanting them. You have to water them more often too.

A border of nasturtiums pull this bed together.

I find it less challenging than choosing perennials. Here are several annuals I like:

Sun

• Ageratum                                                        

• Angelonia

• Gomphrena

• Marigold 

• Zinnia profusion series

• Salvia 'Mystic Spires' (taller)  

Left to right Impatiens, Euphorbia and Coleus (top)

 A lively mix of annuals can make a shade border pop. (above photo)

Shade

• Coleus

• Begonias

• Impatiens

• New Guinea impatiens

• Plectranthus

4. Mass Plants Together:

This is no place to be stingy with plants! Mass them together in groups and plant closely. No gaps.

5.Don't Fight The Site:

Right plant, right place. Know and heed your soil type. Plants that like wet feet won't thrive in dry sandy soil and vice versa. Pay attention to sun and shade requirements. Those that need full sun won't flourish if they are in too much shade. Shade lovers will crisp out in too much sun. Want to make sure your border will look its best? Don't experiment with anything tenuous - invest in zone hardy perennials.

 Choosing edging plants is kind of like doing a puzzle - when you find the right piece it all fits. I probably spend more time on this aspect of a planting than any other. Although I've included my list of tried and trues, my quest continues. Do any of you have a favorite edging plant? If you do, please share and tell us why!