Spiderwort 'Sweet Kate'
Tradescantia 'Sweet Kate' · Commelinaceae
Bright golden-yellow, grassy leaves with deep violet-blue flowers: one of the strongest colour contrasts in a single plant.
- Size
- 16 in tall, 18 in wide
- Zones
- 4 to 9
- Light
- Full sun to part shade
- Flowers
- Early June to late July
- Pets
- Toxic (mild)
- Job in a bed
- Drift
A bed built around spiderwort 'Sweet Kate'
The planner designed this bed around spiderwort 'Sweet Kate' when this page was made: a 12 × 6 ft (3.7 × 1.8 m) English border in zone 6, part sun. It chose the other plants from the 708 that suit those conditions, and says below why spiderwort 'Sweet Kate' stands where it does.
The plants
- 1 Spiderwort 'Sweet Kate' × 3, blue
- 2 Mouse-ear coreopsis 'Nana' × 16, yellow
- 3 Blue moor grass × 9, purple
- 4 Swamp milkweed 'Ice Ballet' × 3, white
- 5 Turtlehead 'Hot Lips' × 5, pink
- 6 Inkberry 'Gem Box' × 1, dark green leaves
- 7 Giant snowdrop × 12, white
Why this plant
- The only open bowls. The others are daisies, spires, flat plates and others. Shape reads at a distance, where colours blur.
- The only blue.
Why here
- Near the front. At 16 in it is the step between blue moor grass (10 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 8 weeks. From early June to late July.
- Fills a gap. For two of those weeks nothing else on the plan is in flower.
Planned as an English border: 7 of the 8 groups (88%) are drifts, longer along the bed than they are deep. The front edge is finished with blue moor grass and mouse-ear coreopsis 'Nana'. Cool colours (blue, purple and pink) with yellow as the warm note, 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: Nothing on this plan is highly poisonous or an aggressive spreader.
Open this bed in the planner Change its size, the sun or the style, move plants about, or swap one for another.
Where spiderwort 'Sweet Kate' goes in a border
At 16 in it belongs at the front of a bed. In the planner's ten height classes it is short (12 to 18 in).
Its job: drift. Planted in a small group of three or five, and repeated further along in the other number.
Blue on gold, a complementary pair built into one plant. The foliage is brightest in sun with moist soil, and scorches if it dries out.
- Gold foliage for moist soil
- Contrast with blue and dark leaves
- Pond sides
What to plant with spiderwort 'Sweet Kate'
Plants recorded as good partners for it, and what each pairing does:
- Hosta 'Halcyon': its blue-green leaves are a setting for the flowers, before and after; bold leaves against its medium ones; happy in the same moist soil.
- Black mondo grass: its black leaves are a setting for the flowers, before and after; low enough (8 in) to stand in front of it.
- Cranesbill 'Rozanne': in flower together for eight weeks, from early June.
Questions about spiderwort 'Sweet Kate'
Does spiderwort 'Sweet Kate' need sun or shade?
Spiderwort 'Sweet Kate' 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 'Sweet Kate' 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 'Sweet Kate' flower in my zone?
In zone 5 it flowers early June to late July. As a summer flower it moves about half a week for every zone: earlier where it is warmer.
| Zone 4 | Mid June to early August |
|---|---|
| Zone 5 | Early June to late July |
| Zone 6 | Early June to late July |
| Zone 7 | Late May to mid July |
| Zone 8 | Late May to mid July |
| Zone 9 | Late 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 'Sweet Kate' be planted?
18 in (45 cm) apart, from the middle of one plant to the middle of the next. That is about its full width, so each plant keeps its own outline.
It grows 16 in (40 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.
How many spiderwort 'Sweet Kate' 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 'Sweet Kate' 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 and the ASPCA. Where references disagree, the more cautious rating is used.
Is there a pet-safe plant like spiderwort 'Sweet Kate'?
These come closest to doing what spiderwort 'Sweet Kate' does, and no toxicity is recorded for them:
- Clustered bellflower: the same job in a bed and the same size; flowers early June to early July, purple, not blue.
- Bluestar 'Blue Ice': the same job in a bed, the same size and the same colour; flowers mid May to late June, wants average soil.
- Pink tickseed: the same job in a bed and the same size; flowers late June to early September, pink, not blue.
Matched the way the planner's Swap button matches plants: the same job in a bed, then size, then flowering time.
What flowers after spiderwort 'Sweet Kate'?
Spiderwort 'Sweet Kate' 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.
- Ornamental onion 'Millenium': from mid July to late August, 18 in tall.
- Japanese anemone: from mid August to early October, 3 ft tall.
What does spiderwort 'Sweet Kate' look like in winter?
Spiderwort 'Sweet Kate' 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 Tradescantia x andersoniana
In these guides
Zone guides: Zone 4 · Zone 5 · Zone 6 · Zone 7 · Zone 8 · Zone 9
Every fact on record
- Type
- Perennial
- Size
- 16 in (40 cm) tall, 18 in (45 cm) wide
- Plant
- 18 in (45 cm) apart
- Height class
- Short (12 to 18 in)
- Place in the bed
- Front
- Flowers
- Early June to late July; open bowls; blue
- Leaves
- Medium texture, herbaceous; chartreuse
- Shape
- Arching, clumping
- 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 and ASPCA poison lists. 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.