Penstemon

Question 1

Pruning

Answer 1

Penstemons can become woody and leggy if they are not pruned annually.
•Trim them once the hard, winter weather is over (usually in late April or early May); until then old stems provide valuable frost protection for the new shoots
•In spring, when new shoots appear at the base, remove the old flower spikes and any suitable material can be used as cuttings
•In autumn, limit windrock and tidy up borders by cutting back penstemon by about a third, being sure to leave enough foliage to provide winter protection

Penstemon pruning
•In mid-spring, check plants for new shoots at the base or along the stems
•Where shoots are growing from the base, cut out all the old stems close to the bottom
•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
•Once a plant has been pruned, remove weeds and other encroaching plants

Question 2

Quick facts

Answer 2

Quick facts

Common name Penstemon
Botanical name Penstemon
Group Perennial
Flowering time Early summer to mid-autumn
Planting time Spring to autumn 
Height and spread 15cm-1m (6in-39in) by 30-60cm (12-24in)
Aspect Sunny 
Hardiness Frost tender to hardy
Difficulty Easy

Question 3

Problems

Answer 3

Penstemons decline within a few years of planting, so replacing with fresh stock every three to five years is often necessary. Plants are more liable to die out in winter where the soil is heavy and not free draining.

Some of the other problems encountered include frost damage and powdery mildew.

A spot in well-drained soil in a sunny bed or border suits them down to the ground (they hate waterlogging

Question 4

Leaf size and relevance according to Titmarsh

Answer 4

Some varieties have narrow leaves and these prove the hardiest. Generally, the broader and fatter the leaves the more tender the plant