Our gardens are under constant threat of invasion. The enemy? Several common British perennial weeds (not to mention the annuals we’ll see in a later article). As these are perennial, they have the nasty habit of hanging around whatever happens. It also renders their removal more difficult.
How to deal with these common British perennial weeds
Organically, the only real eradication method is digging out as much of these plants as possible. They often root deeply or spread widely, so this is no mean feat. If they’re rhizomatous – a rhizome being an underground spreading stem – it’s important to dig out as much of these rhizomes as you can. If they have deep tap roots, they can regenerate from its top part, so we must take out as long a segment of this as able.
Regular hoeing or cutting back of regrowth will significantly weaken the plants over time, but cannot guarantee complete removal. Similarly, you can weaken them by covering the flower bed with thick black polythene. Your prized plants must be carefully removed first however, ensuring no weed roots coming out with them. You’ll also have to leave the polythene in place for much of a year at least, to ensure effectiveness.
If you’re gardening in an eco-friendly way, persistence and patience are key.
If you’re happy to use chemical controls, then this RHS list shows you the range available. Each RHS profile for these perennial weeds will tell you how to chemically eradicate them in more detail. Links can be followed by simply clicking on the weed’s common name.
The weeds
Brambles
Latin name: Rubus fruticosis agg.
Other common names: Blackberry
Insight: Stems can grow up to 2m in length and root when the tip touches the ground.
Couch grass
Latin name: Elymus repens
Other common names: Scutch grass, twitch grass
Insight: Spreading rhizomes which can tangle around the roots of other plants, making removal trickier.
Creeping buttercup
Latin name: Ranunculus repens
Insight: Runners develop from each leaf node, each forming a strong root network when touching the ground. Seeds and severed nodes also aid its spread.
Creeping thistle
Latin name: Cirsium arvense
Insight: It has a deep tap root as well as many seeds carried on the wind. Its roots also spread out and are brittle, meaning any snapped off during extraction can re-shoot easily.
Dandelion
Latin name: Taraxacum officinale
Insight: We’re all familiar with its fluffy seed heads that fly around between March and October. It also possesses a deep tap root from which it can regenerate.
Dock
Latin name: either Rumex obtusifolius or R. crispus
Insight: It has a branching, thick tap root delving up to 90cm deep. Its seeds can survive in the soil for up to 50 years. Digging out at least the top 12-15cm of the tap root should however prevent the individual weed’s regrowth.
Ground elder
Latin name: Aegopodium podagraria
Other common names: Gout weed, bishop weed, jump-about
Insight: Another troublemaker that creeps via its rhizomes, needing careful digging out
Hedge bindweed
Latin name: Calystegia sepium
Other common names: Bellbind
Insight: Its white trumpet-like flowers are pretty, but this is a major pest. Its rhizomes can spread up to 2m a year and the smallest segment of rhizome will regrow.
Horsetail
Latin name: Equisetum arvense
Other common names: Mare’s tail
Insight: Easily recognisable as it resembles miniature pine forests. It’s the opposite of hedge bindweed, sending its roots up to 2m down into the earth. Its rhizomes spread quickly and up spring dense clumps of foliage.
Ivy
Latin name: Hedera helix
Insight: This is invaluable to wildlife and has some uses, but it can smother both horizontal and vertical surfaces if uncontrolled. It’s self-clinging, and when creeping over the ground, it can root at frequent intervals.
Perennial nettles
Latin name: Urtica dioica
Insight: We all know these varmints from their sting. The roots creep under the surface and can send up shoots reaching a maximum of 1.2m in height.
Rosebay willowherb
Latin name: Chamaenerion angustifolium
Other common names: Fireweed
Insight: This plant has attractive pink spires up to 1.5m tall; a white cultivar is available for the larger garden. As a weed, however, its fluffy seeds can fly around on the breeze. Again, its rhizomes spread too, although fortunately it roots shallowly.
