Mature size & growth rate

How big does Cobweb Spiderwort (Cyanotis arachnoidea) get?

Also called Cobweb Spiderwort, White Grass of the Dew, Grass of the Dew.

More about cobweb spiderwort

About Cobweb Spiderwort

Cyanotis arachnoidea · also called Cobweb Spiderwort, White Grass of the Dew · houseplant

Cyanotis arachnoidea is a creeping, softly hairy perennial from tropical Africa and Asia, bearing cobalt-blue or pink three-petalled flowers. Its prostrate stems root freely at nodes, making it an excellent groundcover or trailing basket plant. It needs bright light, well-draining soil, and warm, humid conditions.

Mature size: 5–15 cm tall; stems spreading to 60 cm

Watch for — Leggy, sparse growth: Caused by insufficient light. Move the plant closer to a bright window. Pinch back stem tips regularly to encourage a denser, more compact habit.

Indoor size vs how big it gets in the wild

Cobweb Spiderwort does not get tall — it gets long. Size here is about stem length and how you train or cut it, not how much floor it claims. Indoors and in a pot, expect 5–15 cm tall. In the ground with no restriction it is a completely different plant — stems spreading to 60 cm — which is why the pot, the light and the pruning matter so much for the size you actually end up with.

Growth shows up as lengthening stems that trail down or climb up a support; the plant can be kept tiny or grown metres long from the exact same root system.

Growth rate and years to mature

Cobweb Spiderwort is a moderate grower. Realistically, expect three to six years to reach mature indoor size, gaining a steady amount each growing season. Its feeding profile backs this up: apply a balanced liquid fertiliser at half strength every 3–4 weeks from spring to early autumn. no feeding in winter.

Want this turned into the right next pot at the right moment? The pot size calculator and the cobweb spiderwort repotting guide cover when and how much to size up — pot size is one of the biggest levers on how fast cobweb spiderwort grows.

How to keep cobweb spiderwort smaller

You are not stuck with the maximum size. For cobweb spiderwort specifically, these are the levers, in order of impact:

Trim the longest vines back to the length you want — cobweb spiderwort takes hard cutting well and bushes out from the cut.
Cut just above a leaf node; each trimmed stem usually branches into two, so pruning makes it fuller, not sparser.
The cuttings root easily in water or mix, so "keeping it smaller" doubles as free new plants.
A trim once or twice a season is usually enough to hold its length.

The keep-it-smaller method, step by step

Decide the length you want. Pick the point each vine of cobweb spiderwort should stop — you can be aggressive; it regrows readily.
Cut just above a node. Snip about 0.5 cm above a leaf node so the stem branches there instead of dying back.
Root the cuttings. Drop the trimmed pieces in water or mix — they root in 2-4 weeks and can fill the same pot for a bushier look.
Repeat as it runs. Re-trim whenever it overshoots; regular light pruning keeps it both smaller and fuller.

How to grow cobweb spiderwort bigger or faster

If you want it to fill the space sooner, push the conditions rather than hoping — for cobweb spiderwort the accelerators are:

Good light plus a moss pole or trellis triggers the longest, fastest, largest-leaved growth.
Give it something to climb — many vines grow far faster and bigger up a support than trailing.
Feed through spring and summer and keep it consistently watered while it is actively running.

Light is almost always the ceiling. The cobweb spiderwort light requirements page covers exactly how bright a spot it needs to grow at its potential instead of stalling.

When cobweb spiderwort outgrows the room (or the pot)

"Too big" usually arrives as one of these signs for cobweb spiderwort:

Vines pooling on the floor or wrapping past where you want them — purely a trimming cue, not a repot one.
Bare, leggy stems with leaves only at the tips (usually a light problem, not a size one).
A tangled mass that has outrun its support and needs cutting back and re-training.

If it is the pot rather than the room, it is a repotting job, not a goodbye — see the cobweb spiderwort repotting guide. If you want more of this plant instead of a bigger one, the cobweb spiderwort propagation guide turns prunings into new plants.

Cobweb Spiderwort size — frequently asked questions

How big does cobweb spiderwort get?

Cobweb Spiderwort reaches 5–15 cm tall when grown indoors, and far larger where it grows unrestricted (stems spreading to 60 cm). Growth shows up as lengthening stems that trail down or climb up a support; the plant can be kept tiny or grown metres long from the exact same root system.

Is cobweb spiderwort slow or fast growing?

Cobweb Spiderwort is a moderate grower. Expect three to six years to reach mature indoor size, gaining a steady amount each growing season. Cobweb Spiderwort does not get tall — it gets long. Size here is about stem length and how you train or cut it, not how much floor it claims.

How long does cobweb spiderwort take to reach full size?

Roughly three to six years to reach mature indoor size, gaining a steady amount each growing season. Light, pot size and feeding move that timeline more than anything else.

How do I keep cobweb spiderwort smaller?

Trim the longest vines back to the length you want — cobweb spiderwort takes hard cutting well and bushes out from the cut. Cut just above a leaf node; each trimmed stem usually branches into two, so pruning makes it fuller, not sparser. The cuttings root easily in water or mix, so "keeping it smaller" doubles as free new plants. A trim once or twice a season is usually enough to hold its length.

How can I make cobweb spiderwort grow bigger or faster?

Good light plus a moss pole or trellis triggers the longest, fastest, largest-leaved growth. Give it something to climb — many vines grow far faster and bigger up a support than trailing. Feed through spring and summer and keep it consistently watered while it is actively running.