Weeds are invasive species that drive homeowners crazy. However, these plants are more than just annoying. Left to their own devices, they out compete more than just the plants people want, they can spread into wild grass land and wreak havoc on habitats. Some of the invasive species we’ve listed below are flowers that Calgarians may actually have planted on purpose. We hope that those same Calgarians will remember that the dandelion also started as a pretty garden flower and will promptly remove these invasive species from their yards.

Creeping Bellflower. Often included in “wildflower” seed mixes, creeping bellflower is pretty but invasive. Once it’s established, even a small piece of root can regrow a new plant. Combine that with 15,000 seeds annually plus a resistance to herbicides, and it’s easy to understand why the plant can take over neighbourhoods when left unchecked.

Non-invasive alternatives as suggested by the City of Calgary:

• Native & Ornamental bellflowers (e.g. Carpathian harebell, Campanula carpatica),
• Native & ornamental beardstongues (e.g. Smooth Blue Penstemon, Penstemon nitidus, or Hybrid Beardtongue, Penstemon ‘Pink Chablis’)
• Blue Mirror Delphinium (Delphinium grandiflorum ‘Blue Mirror’)

Dame Rocket. Another hidden invasive species often found in “wildflower” seed mixes (and is usually left off the label!), dame rocket is quick to take over an area. Fortunately, dame rocket roots often come out quite easily when pulled. Dame rocket is known by a variety of names making it harder to avoid when planting.

Non-invasive alternatives as suggested by the City of Calgary:

• Common/garden phlox (Phlox paniculata)
• Southcombe double cranesbill (Geranium oxonianum)
• Purple Smoke Baptisia (Baptisia australis)
• Autumn Joy Sedum (Sedum x ‘Autumn Joy’)

Toadflax. Our final invasive species can also be found in the “wildflower” seed mixes, and is possibly the nastiest of the weeds we’ve outlined. Toadflax not only suppresses natural vegetation, it also carries and passes on diseases to other plants. Like creeping bellflower, once established toadflax is a pain to get rid of, so it’s best if you can catch it early.

Non-invasive alternatives as suggested by the City of Calgary:

• Fine-leaved goldenrod (Solidago graminifolia)
• Goldenrod (Solidago canadensis)
• Annual snapdragon (Antirrhinum majus)
• Dwarf snapdragons (Chaenorrhimun minus)
• Mountain goldenbanner (Thermopsis montana)

Mixed seed packs like the wildflower pack often include hardy invasive species that will take root easily. In general, it’s a good idea to avoid these ready made packs and to select specific plants for your garden. Have a question about weeds in Calgary? Contact the experts at Five-Star Landscaping today!