Hi, I have two Verbena Bonariensis planted in pots a few metres from each other. One has started to lose flowers (see photos) having previously flowered well. The other is still flowering well. Any ideas on why one has started to change? Thanks in advance

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When growing well in the ground it will have long strong leaves on stout stems
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I pot up the few seedlings I get. There's only a few and only because of the mild winters we've had recently. I usually take cuttings - that's my usual method of propagating them, as they often die here over winter. They get potted on until big enough to plant out. I've just done some in the last few days.
They'll grow on quite quickly from the initial potting. I'd never leave them in pots permanently though. You could take cuttings from them, which is quite easy, and will give you more plants if you want them
I live in west central Scotland - not where that photo is...
Devm's looks rather like my plant in the dustbin so possibly bad drainage.