By Honeys
Devon,
United Kingdom 
last year my penstemons made a lot of bushy, floppy foliage and only a few flowers. The soil is not over rich.
19 Feb, 2016
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I am also in Devon, and I would leave them until the weather is a bit warmer then cut them down to a few inches, they will then make nice new growth. Mine were not quite as good as usual last year, so lets hope for a better flowering this year. They are not fussy about the soil.
19 Feb, 2016