The term "groundcover" was new to me when we moved to the USA over 25 years ago. My English gardens never had any bare earth showing, every conceivable space both horizontally and vertically being planted in casual layers of annuals, perennials, edibles, shrubs, and more. There was no additional earth that needed to be covered! Yet I quickly realized that the style of gardening over here was often quite different.
Why Use a Groundcover?
To connect plants
This is the reason I most often use carpeting plants today; to weave in-between immature plantings. It can take three years for plants to become established, during which time the young shrubs and perennials can appear to be sparsely dotted about the landscape. While the temptation is to initially plant these closer together for instant gratification, a better approach is to space them correctly based on their mature size, then interplant them with inexpensive groundcovers that can be thinned out later. This creates a colorful tapestry with lower maintenance and lower cost.
To soften hardscape
Informal flagstone paths beg for those pockets to be planted with something! Should these release a fragrance when stepped on, so much the better but of course selections need to be especially tough to withstand foot traffic.
Even if you have paths that are more formal in design such as concrete or dimensional pavers, the path edges can be softened with a gently mounding or spreading plant.
For safety reasons steps are generally left free of plants since they could become slippery when wet. Yet who can deny the romance of a cloud of tiny white flowers softening these ancient stone steps at Haddon Hall in Bakewell, Derbyshire?
To reduce weeds
This is the reason most often quoted, yet truthfully it is not entirely accurate. The concept is that weeds germinate and thrive in bare earth, so if the soil is covered with plants (a groundcover) there won't be anywhere for the weeds to grow. Trust me – weeds are more tenacious than that! While groundcovers can reduce weed seed dispersal by wind or birds, they wont stop weed seeds already in the soil from germinating unless the groundcover in question is truly dense enough to block light. Nor will they stop weeds with tap roots such as dandelions from poking through.
As a lawn alternative
A huge topic in itself, all I want to say here is that many of the tough, sun loving groundcovers can be used as a lawn substitute. Check out the Steppables website for ideas.
The Disadvantages of Using Groundcovers
I am judicious in my use of groundcovers – here's why.
Soil amendment is hampered
Poor quality soils benefit from an annual top dressing of compost. This can improve drainage in clay soil or can increase moisture retention in sandy soils. If you've used groundcovers extensively you can't get to the soil!
If you apply an organic mulch such as arborist chips or fertile mulch each year, as I do, it can be tricky to avoid these delicate carpeting plants while throwing! (Maybe you have a better aim than me ?!)
They cover the ground…..
I know this sounds like an oxymoron, but many of the plants sold as groundcovers are thugs in disguise. They self-seed and/or spread by stolons or layering, on a mission to take over the world, far-outliving their welcome or the space you had allotted for them.
Weeding is harder
If you've ever tried to weed out clover from a dense patch of groundcover, you know my pain. If you haven't – you've been warned. Book your manicure.
Criteria to Look For
So how do you tell a beauty from a beast?
- They are well behaved! Select plants that can easily be thinned when they overstep their boundaries. Avoid anything with a taproot and do your research, paying special attention to recommendations by local horticulturalists, as invasive behaviors vary widely according to climate and soil conditions
- Drought tolerant. Do you really want to water your pathway?
- Looks good in all four seasons
- Deadheading not necessary. As much as I design "foliage first" I do understand that the addition of flowers can be a lovely boost to carpeting plants. However, I am careful to avoid having to spend hours on my hands and knees snipping off tiny flowers as they fade. While some certainly look tidier if you give them a quick haircut, I don't select varieties that have to be deadheaded to promote further blooms.
My Top 5
My top choice, elfin thyme (Thymus serpyllum 'Elfin'), is a very low growing carpeting thyme ideal for pathways as it won't trip you or your dog up! Plant 12 inches apart for coverage within 2 years.
Attributes: Pretty lavender-pink flowers in early summer and fragrant, evergreen foliage that tolerates light/medium foot traffic. Deer resistant, drought tolerant and rabbit resistant. Attracts bees. Hardy in zones 4-8
Maintenance: cut back with scissors if these spread farther than you would like.
Other varieties to consider: woolly thyme, although I find it is easy to get heels/paws caught in this as it doesn't lie quite as tight to the ground. Lemon thyme is also lovely but taller and more mounding than prostrate and seems to attract slugs although damage is minimal.
Santa Barbara daisy, Profusion fleabane
Actually I'm cheating a little by including the Santa Barbara daisy (Erigeron karvinskianus 'Profusion') as it mostly dies to the ground in the winter in my cold, wet garden but is semi-evergreen in milder areas. I adore this sweet little daisy though – it reminds me of making daisy chains on the lawn as a child.
Attributes: Drought tolerant and deer-resistant but spritz young plants with rabbit repellent. Once they get going they can out-compete the rabbits. Smothered in pink-tipped white daisies all summer long. Tolerates light foot traffic. Hardy in zones 6-9, possibly colder.
Maintenance: tidy up in spring if necessary. In colder regions may take a few extra weeks to come back from the crown.
Fabulous in full or part sun/part shade, the evergreen, golden-yellow succulent foliage of Angelina (Sedum rupestre 'Angelina') really adds a splash of color to the landscape. In winter it will take on an a distinctive orange cast, especially in sunnier spots.
Attributes: Spreads readily from clippings, even in gravel but is very easy to thin or remove and transplant. Hardy in zones 3-11. Drought tolerant and rabbit resistant but deer may nibble.
Maintenance: The stems of yellow flowers in summer add dimension yet the faded blooms are not a distraction and I rarely remove them.
Firewitch is my go-to variety with its neon pink flowers that have an intense clove-like scent but all Cheddar pinks (Dianthus gratianapolitanus) are delightful. The main bloom time is spring with a repeat bloom in fall. The evergreen carpet of blue-gray foliage is also delightful year round. Needs well drained soil.
Attributes: Butterflies love these! Spreads slowly – is never a thug. Tolerates light foot traffic when not in bloom. Deer resistant, rabbit resistant (although they may try some flower buds), drought tolerant. Hardy in zones 3-9
Maintenance: after blooming is completely done, I snip off all the flowering stems with scissors to tidy the plants up.
Other varieties to consider: some popular choices here
Not to be confused with the large shrubs (Cistus spp.), the low growing, evergreen groundcover (Helianthemum spp.) looks as good carpeting the ground as it does tumbling over weathered stone walls. Lots of colors to choose from.
Attributes: thrives in sunny spots with excellent drainage. Tolerates sandy soil. Deer resistant, rabbit resistant, drought tolerant. Hardy in zones 5-9, possibly colder.
Maintenance: pretty much maintenance free if you have the right conditions.
Which is your favorite?
Let me know what your #1 is for sunny spots by leaving a comment.
I'll be back with you in fall – it's time for me to step away from the computer and take some vacation time. Enjoy your summer!