Penstemon; is a half hardy to hardy late summer-flowering perennial depending upon location in the UK
Because of this borderline hardiness, a hard winter may result in serious losses, so it is advisable to propagate plants each year.
Penstemons do not necessarily come true from seed so taking cuttings is the best method to save a particular
named variety or colour.
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Note; Penstemons decline within a few years of planting, so replacing with fresh stock every three to five years
is sometimes necessary.
The 50mm (2") long ‘snapdragon’ like flowers appear in June/July on plants around 600mm (24") high.
Regular deadheading helps to promote a longer flowering season.
Cultivation;
Week 10; Sow seed in trays/pots of seed compost, and germinate at a temperature of 18°C (65°F).
Note; named cultivars from saved seed are unlikely to come true.
Germination should take one to four weeks depending upon variety.
Week 13>; Prick out seedlings into 75mm (3") pots of potting compost when large enough to handle,
and grow on at a temperature of 16°-18°C (61°-64°F) until planting out time in May.
Week 14>; Penstemons can become woody and leggy if they are not pruned annually.
Cut down plants that were partially cut down the previous year to ground level.(see week 42)
Apply a balanced, general-purpose fertiliser at the rate of 70g per sq m (2oz per sq yd),
followed by a 50-75mm (2"-3") thick mulch of well-rotted organic matter around established plants.
Do not over-feed as this may encourage lush leaf growth at he expense of flowers.
Week 16; Take tip cuttings of vigorous cultivars now, and they may flower later in the year.
Follow the procedure detailed below, but as opposed to placing cuttings in a cold frame put them on a hot bed
to speed up the rooting process.
Week 19; Plant out at 400-500mm centres in a sunny or partially shaded sheltered spot with free draining soil,
(they are intolerant to wet conditions).
Prior to planting ;enrich the soil with well-rotted organic matter and 70g per sq m (2oz per sq yd)
of balanced general-purpose fertiliser.
If not done last October, cut established plants down to ground level.
Pot up rooted cuttings into individual 70mm(3") pots.
Watering;
If the soil has been well prepared prior to planting, plants should not need watering unless the weather has
been unusually dry.
Week 33; Tip cuttings can be taken any time in the growing season.
Select non-flowering tip cuttings about 100-120mm (4”-5”) long and trim with a sharp knife to just below a
leaf node.
Carefully remove the bottom leaves and trim the top and side leaves by up to a third to reduce dehydration.
Dip the cutting in hormone rooting gel / powder and insert into a pot / tray containing a 50:50 mixture of
multipurpose compost and vermiculite .
Place pots / trays in a cold frame to root
Week 36; Pot up rooted cuttings into 70mm (3”) pots containing potting compost and grow on in a frost free spot.
Plant out rooted cuttings the following May.
Week 42; to limit windrock cut back established plants by about a third, being sure to leave enough foliage
to provide winter protection.
As an alternative would be to cut down the plants as indicated above (Week 42) and dig them up,
reduce the root ball to a size to fit into a 125-150mm (5"-6") pot, then place the pot/s in a cold frame
or cool greenhouse to over winter.
The greatest benefits arising from this method is;
The plant/s do not require cutting down in spring.
The new root system is able to progress undisturbed, even when potting up into larger pots as the season
progresses.
Further benefit also comes if you want to increase stock, i.e. the plant/s can be brought into warmer
conditions early in the season to produce ‘cutting material’ and it also gets them off to an
earlier start, and subsequently earlier flowering.
Pests & Diseases;
Eelworm; are microscopic nematodes that live within the foliage.
In late summer the infestation generally starts on the lower leaves then spreads upwards causing the foliage
to become purplish then brown as the leaves dry out.
There are no pesticides available to the amateur gardeners, so it is best to destroy any infested plants.
