Common valerian, Valeriana officinalis, is a member of the honeysuckle (Caprifoliaceae) family.
Common valerian is native to Eurasia introduced for use as an ornamental and medicinal plant.
The plant has been present in North America since at least 1890 and has likely benefited from repeated introductions to the continent.
It is a favourite herbal medicine whose use dates back to the father of modern medicine, Hippocrates, who prescribed it as a sleep aid.
The plant has been used to treat ailments including insomnia, anxiety, depression, and headaches.
During both World Wars, valerian was used in treating victims of shell shock (now known as post-traumatic stress disorder).
Valerian remains a popular commodity today, with several million dollars generated each year in sales in the United States.
The PEIISC does not recommend the use of non-prescription herbal remedies like common valerian without the consultation of a physician before use. Talk to your physician before using herbal remedies, as side effects are numerous and can vary between patients.
Here are some key features that may help to positively identify Common valerian:
Grows to 1.5 – 5ft tall
Leaves are compound and pinnately divided.
Leaflets are long with serrated edges, hairy underneath, with 5-25 leaflets per leaf
Stems are thick, fleshy, and ridged
Flowers are white or pale pink, forming in tight clusters at the top of the plant in 2-5 umbrella-shaped umbels, fragrant – very sweet smelling
Blooms June – August
Fruit are lance-shaped, small (0.1 inch), and contain many powdery seeds
Roots are fibrous; small, white, fleshy rhizomes have a pungent odour
Common Valerian spread vigorously by self-seeding and aerial stolons
Look-alikes include: bulbous water hemlock (native), woodland angelica (invasive)
What it does in the ecosystem
Common valerian is a prolific invader of many diverse ecosystems including treed wetlands, meadows, and newly disturbed areas.
It can tolerate a wide variety of conditions
In all of these ecosystems, Valerian is a ready competitor and can spread quickly due to its early emergence and ability to reproduce asexually.
Common Valerian can reproduce by several different means, including by seeds, stolons (runner), bulbils (small outgrowths that lead to the production of whole new plants), and rhizomes (underground stem).
Its vegetative reproduction allows the plant to form dense clumps that gradually expand outwards.
Controlling a common valerian infestation is relatively easy compared to many invasive species, as its seeds do not remain dormant in the soil over long periods. However, the plant is still capable of spreading by seed.
The above qualities may allow common valerian to dominate an ecosystem, reducing local biodiversity and degrading the habitats of native wildlife.
Although the plant has been used medicinally in humans, it is toxic to cattle meaning that the spread of Valerian could lead to the reduced value of pastureland. The PEIISC does not endorse the use of non-prescription herbal remedies like common valerian.
Before selecting a control method, consider the following:
The size of the infestation.
The amount of effort you are able and/or willing to expend. Often, multiple control methods are used simultaneously. Ensure you also consider also the local ecosystem and what other organisms or ecological processes may be affected by management.
Clipping seed heads
Control should be undertaken before the plant goes to seed.
If managing common valerian after seeds appear, carefully clip and bag seed heads before beginning other management to prevent dispersal.
Small infestations of common valerian can be controlled by hand-pulling, as the roots are typically shallow.
Ensure that the entire root is pulled up with the plant, as common valerian may regrow from rhizomes left behind.
The plant can be delicate, so pulling should be done very carefully to avoid breaking off the belowground portion.
For larger infestations, mowing is an option that prevents seed formation but does not kill the plants or reduce the total number of plants.
Seedlings too low to mow will be unaffected by this treatment.
Chemical control methods exist, but the PEIISC does not offer advice on chemical control measures at this time.
It is unlawful to use herbicides when close to wetlands and watercourses on PEI.
As common valerian often grows in moist areas, in many cases chemical controls will not be a viable option.
If using chemical controls, it is imperative that all local legislation and manufacturer’s instructions be followed during application.
When managing invasive species by any method nearby a watercourse, you must obtain a Watercourse, Wetland and Buffer Zone Activity Permit from the PEI Department of Environment, Energy, and Climate Action.
Apply for this permit at least six weeks before beginning control efforts.
When control efforts are completed
It is crucial that all equipment used be fully cleaned of all plant parts before moving on to prevent inadvertent spread.
All plant parts should be bagged in clear bags and properly disposed of.
Each time you manage the site, collect, bag, mark, and dispose of all plant parts properly.
Bag the plant material in clear plastic bags.
Mark the bags boldly with a permanent marker. Write “INVASIVE PLANT” or “COMMON VALERIAN” on the bags.
If you have a place away from foot and wildlife traffic, you can dry out the material, making it much easier to move.
Leave the bags open and in the sun for a week to dry.
Only do this if you can guarantee that the plant will not be spread from where it is drying
If the bags are thin, double bag to prevent accidental dispersal.
Tie the bags tightly and place them in your usual residential waste collection (THE BLACK BIN)
Never place invasive plants into the compost. This may allow them to become established once they reach the heap.
For loads larger than what will fit into a ½ ton truck, reach out the the PEIISC for specific disposal instructions.
As a bonus, one can collect valerian roots to be used later in a valerian root tea, but for safety reasons, this should never be attempted unless the plant’s ID is confirmed with a professional. Only collect roots from clean places far from sources of pollutants.