Ornamental · Ranunculaceae
Meadow Rue
Thalictrum rochebruneanum
With airy clouds of bloom on tall, slender stems, meadow rue brings soft height and easy motion to a shady border you'll feel proud of.
Partial shade
Every 5–10 days
USDA 4–7
4–6 ft · 1.2–1.8 m
Overview
If this is your first go at a tall perennial, meadow rue is a wonderfully forgiving place to start. It's a clump-forming plant in the buttercup family, grown for the mist of tiny flowers it lifts high above lacy, columbine-like foliage. The stems can rise well over head height on some types, yet the whole plant stays light and see-through, so you can look right through it to whatever grows behind.
The good news is that this is an easy plant to please once it's in the right corner. Give it part shade and steady moisture and it settles in happily, since it only sulks in dry, baking sun. It suits the cooler, damper spots of a garden across zones 4 through 7, and once it's comfortable it asks almost nothing more of you.
There's just one thing to know before you plant it, and it's simple to work around. Meadow rue sits in the same family as the buttercups, so its sap is an irritant, and no part of it is food despite that misleading common name. Think of it as a plant to admire rather than one to handle bare-handed, and you and it will get along just fine.
Care
The short version: give it part shade, rich and reliably moist soil, and a bit of afternoon shade where summers run hot. Slip a support under the tall types early, cut the plant to the ground in late fall, and only divide the clump when it starts to crowd itself.
Light
Meadow rue is happiest in part shade, and it will take full sun only where the soil stays moist and the summers stay mild. In hot regions, do give it afternoon shade, since harsh midday sun can scorch the leaves.
Water
Keep the soil consistently moist but never soggy, watering roughly every 5 to 10 days and a touch more in a dry spell. Plants in full sun drink more than those in shade, and it's a thirsty plant in heat that scorches first, so a little attention here goes a long way.
Soil
Give it rich, humusy, well-drained loam that holds moisture without going waterlogged. It really isn't fussy about pH and grows happily in acid, neutral, or alkaline ground, so the texture matters far more than the chemistry.
Temperature
Meadow rue is beautifully hardy, shrugging off winter cold down to about -29°F (-34°C) and coping with summer warmth up to around 86°F (30°C). Its one weak spot isn't the cold at all but hot, humid weather, which is exactly when afternoon shade earns its keep.
Humidity
Ordinary outdoor humidity suits it just fine, so there's no figure you need to chase. What really counts is air movement, since still, muggy air around crowded leaves is what tends to invite powdery mildew and rust.
Feeding
Work a little compost or a balanced feed into the soil as growth starts in spring, and that's usually all it needs for the whole year. Rich, humusy ground does most of the feeding, so there's no need to reach for heavy fertilizer here.
Pruning
Cut the spent flower stems back after bloom to keep things tidy, then cut the whole plant to the ground in late fall or early spring. The tall species often welcome a stake, while the sturdy-stemmed types happily stand on their own.
Repotting
Meadow rue likes to stay put and quietly resents being disturbed. Divide the clump only every 3 to 4 years, in spring while it's dormant, and only when crowded, declining growth or smaller leaves are telling you it wants a fresh start.
Size & spacing
In flower these plants stand 4 to 6 feet (122 to 183 cm) tall, rising on slim stems from a much lower mound of leaves. Give each clump about 2 to 3 feet (61 to 91 cm) of room so air can move freely and the foliage stays nice and dry.
When to plant
Meadow rue keeps easy time with a cold-winter garden. Sow fresh seed in fall or start it indoors in late winter, set your young plants out once the spring frost has passed, and you'll be rewarded with airy flowers opening from midsummer into early autumn.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: Late winter to early spring; fresh seed germinates best, so fall sowing of fresh seed is also effective.
- Plant: Spring after frost, or fall.
- Harvest: July to September
Hardiness
USDA hardiness zones: 4–7
Temperature: down to -34°C
Troubleshooting
Take heart, meadow rue is a healthy plant, and nearly all its trouble comes from stale air or summer heat rather than anything serious. Learn to spot the early signs on the leaves and stems, and you can step in well before a fungus or a hot spell gets a real hold.
Crisped, drooping leaves during a summer heat spell
Meadow rue simply isn't fond of hot, humid weather, and it can scorch in full afternoon sun, most of all when the soil has gone dry. The fix is easy and forgiving: offer it afternoon shade where your summers get fierce, and keep the ground evenly moist. A cozy layer of mulch holds that moisture in and keeps the roots pleasantly cool.
Fix:
- Provide afternoon shade in hot climates
- Keep soil evenly moist
- Mulch to conserve moisture
A soft white dust appearing across the leaves
Don't worry, this is only powdery mildew, a fungus that shows up when the air stays still and damp around the plant. You can turn it around by thinning and spacing so a breeze can pass through, and by keeping your watering aimed at the soil rather than the leaves. Pluck off the most affected foliage and put it in the bin instead of the compost.
Fix:
- Improve air circulation by thinning and spacing plants
- Avoid overhead watering
- Remove and discard affected foliage
Little orange-brown bumps under the leaves
These raised spots are rust, one more fungus that likes wet, crowded leaves, and it is easy to get on top of. Gently remove the spotted leaves and get rid of them, then loosen the clump so the remaining foliage can dry off quickly after rain. Watering low, right at the base, keeps the whole plant much happier.
Fix:
- Remove and destroy infected leaves
- Improve air circulation
- Avoid overhead irrigation
Tall stems leaning over under the weight of their blooms
This is simply top-heavy growth, and it shows up more on older plants or ones grown in a bit too much shade or wind. The kind trick is to slip a support in nice and early, before the stems begin to lean, because once they flop they seldom rise again. A brighter spot builds stronger stems, and the toughest types will happily hold themselves up.
Fix:
- Stake or provide support for tall stems
- Site in adequate light to promote sturdier stems
Toxicity
Handle meadow rue with just a little care and all will be well. Like the rest of the buttercup family, its sap holds protoanemonin, an irritant that can redden skin and upset the stomach if any part is chewed. Nothing on the plant is edible, so keep the leaves and cut stems away from pets, livestock, and children, and slip on gloves when you prune.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds · People
Cats Mild
If a cat nibbles a leaf, you might see it drool and paw at its mouth, perhaps with a little vomiting or a loose stool. Happily, the bitter, peppery sap usually turns them away before they swallow much at all.
Dogs Mild
Should a dog bite into a stem, keep an eye out for drooling, a sore mouth, and a short bout of vomiting or diarrhea. The harsh taste tends to stop most dogs after that very first nibble, so serious trouble is rare.
Horses Mild
The irritant sap can leave a grazing horse with a raw mouth and a touch of mild colic, though the sharp flavor means most horses take no more than a taste and move on.
Rabbits Mild
A curious rabbit that samples the foliage may end up with a bit of mouth irritation and slightly soft stool. Reassuringly, most leave it well alone once they meet that acrid sap.
Livestock Mild
Cattle, goats, and sheep can pick up a sore mouth and an unsettled gut from the protoanemonin in the leaves, but the bitterness keeps their grazing down to very little.
Birds Caution
There isn't much firm guidance for birds, so it's wise to treat the plant as a caution and simply tuck cut stems and trimmings somewhere they cannot reach.
People Caution
No part of meadow rue is food. The fresh sap can redden or irritate skin and sting the mouth, so slip on gloves when you cut stems and keep the plant out of the way of small children.
Wear gloves when cutting or handling cut stems to avoid sap contact with skin; wash hands after handling and keep cut foliage away from pets and small children.
Helpline numbers
United States
ASPCA Animal Poison Control: (888) 426-4435 (fee applies)
Poison Control: (800) 222-1222
Canada
Poison Centres: 1-844-764-7669
Varieties
A handful of meadow rues turn up in gardens, from sturdy giants to soft, fluffy-flowered species. Here are the ones well worth knowing by name.
Thalictrum rochebruneanum Lavender Mist
You'll love that this selection floats a haze of lavender-purple flowers and yellow stamens on tall, sturdy stems that hold themselves up beautifully without any staking.
Thalictrum aquilegiifolium
Called columbine meadowrue, this one grows a friendlier 2 to 3 feet (60 to 90 cm) and carries fluffy powder-puff heads of pink, purple, or white above soft columbine-like leaves.
Thalictrum delavayi Hewitt's Double
This charmer bears long-lasting fully double lavender flowers that keep their color far longer, since with no stamens to shed they simply stay put.
How to propagate
You can make more meadow rue by splitting an established clump or by raising it from seed. Neither route is quick, but both reward a patient gardener, and you have plenty of both patience and time.
DivisionModerate
Spring while dormant, roughly every 3-4 years. · Divisions may be slow to establish, often a season or more.
Lift the clump gently in spring while it's still dormant and split the crown, and you only need to do this every 3 to 4 years, once a plant begins to crowd itself. Keep your new divisions evenly moist and be kind about giving them time, because they often take a season or more to settle in and look properly established.
SeedModerate
Sow fresh seed in fall, or start indoors in late winter to early spring. · One to several years to reach flowering size from seed.
Sow fresh seed in fall, or start it off indoors in late winter to early spring, since fresh seed germinates far better than seed that has been sitting around. Tuck the seedlings into rich, moist, humusy soil and hold onto your patience, because a plant grown from seed can take anywhere from one to several years to reach flowering size.
Myths
Meadow rue is a true rue and works the same way in herbal recipes.
It's an easy mix-up, but the shared name is misleading. Meadow rue is a Thalictrum in the buttercup family, while true rue is Ruta graveolens, a citrus-family herb it simply isn't related to. Meadow rue is not a cooking or medicinal herb, and its sap is an irritant, so please don't treat the two as interchangeable.
Buttercup-family ornamentals like meadow rue are completely harmless to handle.
Plants in this family carry ranunculin, which becomes the irritant protoanemonin the moment the tissue is crushed or chewed. Fresh sap can redden your skin and upset your stomach if swallowed, so there's no need to fear it, just pop on gloves whenever you cut the stems.