Every week on GardenLine on WXTK I start the show off with “I Love This Plant/I Hate This Plant.” One look at the titles of most of these blog posts will show you that the plants I love far outnumber the ones I hate. Frankly, there are far more plants that I feel neutral about than there are plants I dislike. I am not fond of blue rug junipers, however, and here’s why.
Name: Juniperus horizontalis ‘Wiltonii’ aka blue rug juniper
Type of Plant: Drought tolerant plant for full sun and dry conditions. Hardy in zones 3 to 9
Why I Love/Hate this plant: I hate this plant because as it ages it isn’t very attractive and as a groundcover it doesn’t do its job well. What appears to be thick, bluish foliage when the plant is young quickly grows into a sprawling, bare-stemmed plant with attractive growth on the end of the plant but bare stems and dying older foliage on the inside. These bare areas allow weeds to grow in those spaces, and soon the plants are weed ridden and unattractive. Since the plants are prickly, pulling weeds out is not fun!
A Word to the Wise: Junipers are good plants for dry areas, but some do their job better than others. Where the green mound juniper (Juniperus procumbens ‘Nana’) grows tightly enough to keep most weeds away, blue rug is just the opposite. If you must grow it (why?) try planting them two to three feet apart so that the green growth of one will move into and over the bare areas on neighboring plants.
People plant junipers in sunny places where drought-tolerant plants are needed, so it’s not surprising that they were used in this bed with Nippon daisies and Mugo pines.
But this planting shows my problem with these plants. These are fairly new in this bed and they are already showing bare interiors and infestations of weeds.
Hi CL,
I have a walkway with a granite step up to another walkway. I have peonies on either side of the top of the step, with a eroding 10 inch drop down to the first walkway, on each side, about 15 inches from the base of the peonies. Last fall I planted Blue Pacific juniper on either side, under the peonies, to prevent erosion; they did not make it. I just purchased Blue rug juniper to replace them. Unfortunately I just read an article that stated “junipers” emit a chemical to prevent other plants from growing nearby that would harm peonies. Any experience with this? Should I assume ground cover junipers will do this? The peonies are my top priority; should I find a different evergreen ground cover (miniature thyme is not doing the job)?
Thank you,
Andrea
Andrea,
There is some evidence that the genus Juniperus contains compounds that are allelopathic…that inhibit the growth of some other plants. However, I have never observed that the ground-hugging junipers do this. In fact, I have the Green Mound juniper growing over and around several other plants with no detrimental effect. And since the genus Juniperus is pretty huge, I think it’s impossible to say that they all produce the same compounds, and there is no university research that I can find that shows that Blue Rug is allelopathic – it’s in the species horizontallis. I find research showing that the species scopulorum does inhibit some other plants’ growth. BTW I have found that wooly thyme is a good, low groundcover and it turns kind of lavender color in the winter…