Thickleaf beardtongue (Penstemon pachyphyllus) is a member of the large Penstemon genus of native wildflowers. This perennial plant grows wild in Arizona, Colorado, New Mexico, Nevada, Utah and Wyoming. Its flowers are sky blue to lavender. It grows to 4 feet high. It helps to control erosion in the high altitude areas where it occurs---from about 5,000 to over 8,000 feet. If you live in such an area and have well-drained, rocky soil and you get lots of sun, you can grow this Penstemon. Pruning it twice each year helps to keep the plant tidy and also encourages it to bush out and produce more flowers from May through July.
Pruning Thickleaf Beardtongue
Prune your thickleaf beardtongue twice each year, in spring and fall. Pruning helps to keep this plant from becoming woody and unruly. Wait until after your final spring frost to prune.
Cut off all old flower spikes to the plant's base in April or May after the plant has begun to put out new growth.
Prune all old, woody stems where they connect at the bottom of the plant. If no new growth is evident, merely shorten the old stems above the lowest leaves.
Reduce your thickleaf beardtongue by about one third in the fall, making certain to leave enough foliage to protect the interior of the plant from frost and snow.
Remove weeds and other undesirable plants from this beardtongue's environment after you prune it in the fall.