Normal end of an annual's life
An annual herb yellowing from the base, going coarse and collapsing after it has flowered and set seed. Nothing has gone wrong: the plant's whole life is one season and it spends the last weeks of it moving everything it has into seed. Borage does this in August, summer savory in October, and shiso once the days shorten enough to bring it into flower — and in each case the standard response of feeding and watering harder is work done against a plant that has finished.
What brings it on
Flowering and seed set, which for most culinary annuals arrives in the second half of summer and is hastened by heat, drought and any check. Once seed is setting the plant withdraws nitrogen and magnesium from its oldest leaves — which is why the yellowing starts at the bottom and looks so much like a shortage of both.
source
Sourced guidancehigh confidence
- Royal Horticultural Society: Growing annual herbs
- Plant Finder — Missouri Botanical Garden: Annual herbs — life cycle
Checked 2026-08-13
Usually seen: July, August, September, October
Preventing it
Ordered by how much difference each measure actually makes, not by how often it is repeated.
- Not preventable, and worth saying plainly because the two standard responses — a feed and a heavy watering — both make it worse rather than better. What extends the useful season is a second sowing made in midsummer, not an intervention on a plant that is already going over.
source
GrowingHQ editorial positionhigh confidence
A judgement about what the differential is allowed to recommend for a plant at the end of its life, rather than a horticultural fact.
- GrowingHQ editorial synthesis — GrowingHQ
Checked 2026-08-13
Dealing with it once it is there
- Take what leaf is still worth having, then decide what the plant is for. Left standing, borage and shiso seed themselves and come up on their own next year; pulled and composted, the ground is free for something else. Either is a decision rather than a rescue.
source
Sourced guidancehigh confidence
- Royal Horticultural Society: Growing annual herbs
Checked 2026-08-13
Widely repeated, and not supported
Recorded so GrowingHQ can address them. These are not alternative approaches — they are things the evidence does not back.
“An annual herb yellowing from the bottom needs feeding.”
Yellowing that begins at the base of a flowering annual in late summer is the plant recovering what it can from its oldest leaves. Nitrogen applied at that point produces soft growth on a plant that will be dead within weeks, and it does not restore the leaves already lost.
Horticultural consensusCommonly said, not supportedmoderate confidence
- Royal Horticultural Society: Growing annual herbs
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.