Common name: Beard Tongue
Depending upon location in the UK Penstemons are a half hardy to hardy perennials.
Due to this borderline hardiness it is advisable to propagate plants each year as an insurance against serious losses during hard winters.
Similarly, as they are short-lived perennials, plus the fact that the quality of the plants can decline within a few years of planting, replacing with fresh stock every three to five years is advisable.
In the event that you have to change your stock be advised that plants do not necessarily come true from seed, meaning that if you would like to save a particular named variety, or colour taking cuttings is the best method to do this.
Planted out in Border
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.
Sow seed in trays/pots of seed compost, and germinate at a temperature of 18°C (65°F).
Named cultivars from saved seed are unlikely to come true.
Germination should take seven to ten depending upon variety.
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.
Plants 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.
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.
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.
If the soil has been well prepared prior to planting, plants should not need watering unless the weather has been unusually dry.
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.
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.
To limit windrock cut back established plants by about a third, being sure to leave enough foliage to provide winter protection.
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 are;
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 and 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.