Spiderwort
Tradescantia x andersoniana · Commelinaceae
Three-petalled flowers in purple, blue, pink or white open each morning among arching, grass-like leaves, for many weeks in early summer.
- Size
- 24 in tall, 24 in wide
- Zones
- 4 to 9
- Light
- Full sun to part shade
- Flowers
- Late May to late July
- Pets
- Toxic (mild)
- Job in a bed
- Drift
A bed built around spiderwort
The planner designed this bed around spiderwort when this page was made: a 12 × 6 ft (3.7 × 1.8 m) cottage garden in zone 6, part sun. It chose the other plants from the 708 that suit those conditions, and says below why spiderwort stands where it does.
The plants
- 1 Spiderwort × 3, purple
- 2 Lingonberry × 7, pink
- 3 Mouse-ear coreopsis 'Nana' × 16, yellow
- 4 Northern sea oats × 3, tan
- 5 Brown-eyed Susan × 5, yellow
- 6 Inkberry 'Gem Box' × 1, dark green leaves
- 7 Double snowdrop × 12, white
- 8 Spring starflower × 12, blue
Why this plant
- The only open bowls. The others are bells, daisies and airy sprays. Shape reads at a distance, where colours blur.
- The only purple.
Why here
- In the middle. At 24 in it is the step between lingonberry (8 in) in front and inkberry 'Gem Box' (2½ ft) behind: each is seen over the one before.
- 3 plants in one group. Massed, one kind reads as a single shape. Scattered, it would look spotty.
Why now
- In flower for 9 weeks. From late May to late July.
- Fills a gap. For five of those weeks nothing else on the plan is in flower.
Planned as a cottage garden: 35 of the 35 plants (100%), bulbs aside, stand alone or in groups of no more than five, small enough for the kinds to mingle. Mouse-ear coreopsis 'Nana' is planted in four places along the bed, which gives it rhythm. The scheme leans cool (purple, pink and blue) and uses yellow for warmth, with tan and white to calm things between them.
The planner's own design check: 12 Excellent, 4 Good, 1 Satisfactory. It flags one thing to watch: Northern sea oats spreads aggressively. Each plant's details say more.
Open this bed in the planner Change its size, the sun or the style, move plants about, or swap one for another.
Where spiderwort goes in a border
At 24 in it belongs in the middle of a bed. In the planner's ten height classes it is medium short (18 to 24 in).
Its job: drift. Planted in a small group of three or five, and repeated further along in the other number.
It looks ragged by midsummer: cut the whole plant to the ground for fresh leaves and more flowers in autumn. Plant it behind something that hides it in the meantime.
- Moist borders and pond sides
- Flowers in part shade
- Cottage gardens
What to plant with spiderwort
Plants recorded as good partners for it, and what each pairing does:
- Lady's mantle: in flower together for six weeks, from late May; happy in the same moist soil.
- Siberian iris: in flower together for four weeks, from late May; happy in the same moist soil.
- Daylily: purple against yellow, opposite each other on the colour wheel, if you choose those colours, in flower together for five weeks.
Questions about spiderwort
Does spiderwort need sun or shade?
Spiderwort grows in full sun (6 or more hours of direct sun a day), part sun (4 to 6 hours of sun, including some afternoon sun) and part shade (2 to 4 hours of sun, mostly in the morning).
It wants soil that stays evenly moist, of average fertility, and a good soak in dry spells.
What zones does spiderwort grow in?
USDA zones 4 to 9. It is hardy to zone 4, which means it survives winter nights down to about −20 °F (−29 °C).
Gardening in Canada? Use the USDA zone for your town: Canada's own zone map uses different numbers.
When does spiderwort flower in my zone?
In zone 5 it flowers late May to late July. As a spring flower it moves about a week for every zone: earlier where it is warmer, later where it is colder.
| Zone 4 | Early June to early August |
|---|---|
| Zone 5 | Late May to late July |
| Zone 6 | Late May to late July |
| Zone 7 | Mid May to mid July |
| Zone 8 | Early May to mid July |
| Zone 9 | Early May to mid July |
Worked out from Hopkins' bioclimatic law: spring arrives about four days later for each degree of latitude north, and one zone is roughly two degrees. A warm spring or a cold one moves any garden two weeks either way.
How far apart should spiderwort be planted?
18 in (45 cm) apart, from the middle of one plant to the middle of the next. That is a little closer than its full width of 24 in (60 cm), so a group knits into one patch.
It grows 24 in (60 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.
How many spiderwort plants do I need?
At 18 in apart, set out in staggered rows:
- 5 to fill 10 square feet (about 1 m²)
- 7 for a single row 10 ft (3 m) long
- 17 to fill a 4 × 8 ft bed on its own
In a mixed border, plant it as a group of three or five, with a second group further along in the other number.
In the bed above, the planner used three in one group.
Is spiderwort poisonous to dogs and cats?
Yes: mild toxicity to people, dogs, cats and horses. The sap can irritate the skin of people and pets.
Rated from NC State Extension. Where references disagree, the more cautious rating is used.
Will spiderwort spread?
It seeds itself about; the risk of it taking over is moderate. Self-seeds freely. Remove the spent flowers to limit seedlings.
What flowers after spiderwort?
Spiderwort is over by late July. These start as it finishes and carry the same spot on, so it never goes flat:
- Lilyturf: from early August to mid September, 16 in tall, to stand in front of it and cover its fading stems.
- Ornamental onion 'Millenium': from mid July to late August, 18 in tall, to stand in front of it and cover its fading stems.
- Japanese anemone: from mid August to early October, 3 ft tall.
What does spiderwort look like in winter?
Spiderwort dies down to the ground and there is nothing to see until spring. The old stems can be cut in autumn, or left until spring as shelter for overwintering insects.
More Tradescantia
- Ohio spiderwort Tradescantia ohiensis
- Spiderwort 'Sweet Kate' Tradescantia 'Sweet Kate'
In these guides
- Garden plants toxic to cats
- Garden plants toxic to dogs
- Plants with blue flowers
- Plants for a white garden
Zone guides: Zone 4 · Zone 5 · Zone 6 · Zone 7 · Zone 8 · Zone 9
Every fact on record
- Type
- Perennial
- Size
- 24 in (60 cm) tall, 24 in (60 cm) wide
- Plant
- 18 in (45 cm) apart
- Height class
- Medium short (18 to 24 in)
- Place in the bed
- Middle
- Flowers
- Late May to late July; open bowls; purple, blue, pink, white
- Leaves
- Medium texture, herbaceous; green
- Shape
- Arching, self-seeding
- Hardy in
- USDA zones 4 to 9
- Light
- Full sun, part sun, part shade
- Soil
- Average, evenly moist
- Water
- Moderate
- Feeding
- Light, in spring
- Family
- Commelinaceae
Checked against NC State Extension. Flowering times are for zone 5: later in colder zones, earlier in warmer ones. Toxicity and spread information is a general gardening guide, not veterinary or medical advice, and invasive status varies by region. If a person or pet eats a plant, contact poison control or a vet. Check your local invasive species list before planting anything with a spread warning.