Advice
RHS Help & Advice
Pruning Penstemon
Penstemons have become increasingly popular over recent years for their flowers that are now available in a wide range of colours produced over many weeks in the summer.
Penstemons can become woody and leggy if they are not pruned annually. So, to keep plants neat and compact, give them a trim once the hard, winter weather is over (usually in late April or early May). This timing ensures that the old stems are still there to shelter the new shoots from any damaging late frosts.
Step 1
Examine plants individually to see whether the new shoots come from the base or are just appearing along the stems.
Step 2
Where shoots are growing from the bottom, cut out all the old stems close to the base (shown here). Penstemon with few or no shoots growing from ground level should only have their stems shortened, making the cuts just above the lowest set of healthy leaves.
Step 3
Once a plant has been pruned (shown here), remove weeds and other encroaching plants. Apply a general fertiliser, such as Growmore, to the soil to encourage strong growth.
Timely tip
New plants can be propagated from the strong sideshoots attached to the stems you’ve cut off.
For more details click here
Leigh Hunt