By Snoopdog
shropshire,
United Kingdom 
we have a couple of bogs of penstemen now getting big enough as needs to be made smaller when and can they be split to make another planting would i cut with spade or pull apart
13 Jun, 2012
Best time would have been spring Snoop, I would now wait until Autumn. They should be easy enough to pull apart with your hands if it's Penstemon digitalis. Penstemon grandiflorus is a little bit tougher and you may need a knife.
If you want to increase the number of plants even more, you can earth up in the crown of the plant and come spring it will have set good new roots in there you can then divide and pot on and divide the main plant as normal.
13 Jun, 2012