Foliage that is meant to look like that
New growth that is rolled, puckered or crimped because it has not finished expanding, or because the plant's mature leaf is simply not flat. Lemongrass pushes every leaf out as a tight rolled spear; borage unfolds its young leaves from a deeply puckered bud under a coat of white bristles; the crisped forms of shiso are sold for a leaf surface that is quilted between the veins. All three are read as aphid damage or virus, and the giveaway is the same in every case: the distortion is on every new leaf equally, there is nothing living in it, and the leaf firms up rather than staying limp.
What brings it on
Visible whenever the plant is growing, which is what separates it from every cause it is mistaken for. A pest or a cold night produces one band of damaged growth with normal leaves above and below it once the cause passes; a leaf that emerges rolled emerges rolled in April, June and September, on every shoot, for as long as the plant lives.
source
Sourced guidancemoderate confidence
- Royal Horticultural Society: Lemongrass — cultivation
- Plant Finder — Missouri Botanical Garden: Perilla frutescens
Checked 2026-08-13
Preventing it
Ordered by how much difference each measure actually makes, not by how often it is repeated.
- Nothing to prevent. The useful habit is to look at a plant when it is healthy, so that its normal new growth is familiar before anything goes wrong with it — most of the misdiagnosis here comes from a grower meeting a plant's young foliage for the first time and having nothing to compare it against.
source
Horticultural consensusmoderate confidence
- Royal Horticultural Society: Herbs — growing guide
Checked 2026-08-13
Dealing with it once it is there
- Leave it and look again in a fortnight. A rolled lemongrass spear will have opened into a flat blade, and a puckered borage leaf will have expanded and flattened; a leaf distorted by feeding stays distorted for its whole life, because the cells that failed to expand cannot expand later.
source
Horticultural consensusmoderate confidence
- Royal Horticultural Society: Aphids
Checked 2026-08-13
- Open one rolled shoot and look inside before deciding. That single check separates this from the two causes it is confused with — aphid colonies sit in the fold and cold damage leaves the tissue translucent or blackened — and it costs one leaf.
source
Horticultural consensusmoderate confidence
- Royal Horticultural Society: Aphids — identification
Checked 2026-08-13
What it affects
On sprays and treatments
GrowingHQ does not tell anyone what to apply, at what rate, or how often. Pesticide approvals differ by country, change without notice, and the product label is legally binding — it is also the document you are holding. What is described here is cultural and physical control, which is what a home grower can act on without a label in front of them.