Purple loosestrife

By Teresa Woodard

So, your kind neighbor calls to offer some free plants. Do you accept willingly?  Well, that depends.  Many well-intentioned gardeners like to share their plants, but often their plants can be more of a nuisance than a blessing as they proliferate and crowd out the other plants in your garden.  Pretty soon, all you have is a garden of neighbor’s lovely gift.

If a neighbor knocks at the door with an armload of any of these freebies, carefully consider the offer:

Aggressive Plants ­– Many of these plants can be planted in an area where they are contained or where an area needs filled.  For example, I grow mint in a container and plant cleome in a bed where I can easily thin the abundance of new seedlings that return each year from this self-sower.

Bachelor button (Centaurea montana): I gained my first bachelor button at a plant swap.  I love the cottage look this plant brings to the garden but get frustrated by having to pull an abundance of new plants that emerge in many unwanted spaces.

English ivy

English Ivy (Hedera helix):  This gifted plant has taken over many of my perennials including my beloved Lady’s Mantle.  Good alternatives to this vine are sweet woodruff, wild ginger and wood aster (Eurybia divaricata).

Mint (Mentha):  Mint’s great to have on hand to add to tea and mojitos, but its roots send up unwanted shoots if not kept in a container.

Passion flower (Passiflora incarnata):  My husband was drawn to the amazing blooms on this vine, but its aggressive nature has become a bane in our garden.  Planted along our garden fences, the vine’s spreading roots send up new shoots throughout the garden, and these new vines rapidly take over if not pulled.

Spider Flower (Cleome):  These big spider-shaped blooms are followed by seed pods loaded with lots of seeds.  I plant them in a cutting garden but ruthlessly thin the new seedlings.

Creeping Jenny

Creeping Jenny (Lysimachia nummularia): I innocently planted this “spiller” in a container garden and found it jumped to a nearby bed where it quickly spread.

Invasive plants – Several plants are listed as “invasive” in that they threaten other native plants in natural areas.  Environmentally responsible gardeners should keep these harmful plants from their landscape.

Purple loosestrife (Lythrum salicariaand its cultivars and hybrids): This popular magenta-spiked garden flower grows three to seven feet tall and has a dense bushy growth of one to 50 stems. Purple loosestrife spreads aggressively by underground stems (rhizomes) and can produce as many as a million seeds per plant. Supposedly sterile strains of L. virgatum will outcross with this plant and produce seeds.

Lesser celladine (Ranunculus ficaria): This buttercup-like plant forms a green mat and chokes out other spring wildflowers. And it leaves behind small tubers when you pull it from the soil which explains its masses of plants.

Creeping Jenny — a great in a container but aggressive in a flower bed