POTENTILLAS FOR THE UK GARDENER
Article by DavidMarks
Potentillas are deciduous (lose their leaves over winter) shrubs which grow well inour climate. There are several species but almost all those sold in the UK are known as
Potentilla fruticosa and these are covered by this article. In some older articlesthese shrubs are called Cinquefoil but this name is rarely used nowadays.
The following featurelist should help you decide if a Potentilla is suited to you and your garden conditions:
- Potentillas flower from May to the end of August. The peak flowering time is early Mayto June.
- When established they require no feeding if your soil is average fertility and in mostparts of the UK they will not need to be watered at all unless the soil is very light /sandy.
- They are deciduous and begin to loose their leaves in November, regaining them again inApril / May time.
- Potentillas are fully hardy throughout the UK.
- They prefer full sun for the flowers to develop to their best but will still thrive inpart shade. If you have sun for five or more hours a day they will be fine.
- Potentillas are long-lasting shrubs and will live for fifteen years or more.
- Sizes vary from 25cm / 10in to 2m / 6ft high.
- They are readily available from garden centres and online suppliers in a wide choice ofvarieties and colours.
- They grow equally well on a wide range of garden soils.
- Potentillas are deer resistant and very unlikely to be eaten by deer.
- Potentillas tolerate neglect well because their nutrient and water requirementsare low and they grow well with minimal pruning.
HOW TO CARE FOR A POTENTILLA
Potentillas are one of the lowest maintenance shrubs and when established require no attentionother than pruning to keep them to the size you want. No special techniques are required, asimple "haircut" will do them fine. If they get out of hand the best treatment is to cut themback hard and wait for them to reappear the next year.
Potentilla can in fact be pruned down very close to the ground and they will soon reappear.They may not flower as well in the first year but after that they will dofine. They can be pruned at any time of the year but September is good time if you want them to flowerwell the next year.
Potentillas grow best on slightly poor soil and in slightly drier than normal conditions. Sodon't be tempted to feed them and only water in drought conditions.
The best time to plant a newly bought potentilla is in late September inthe UK. The ground will be warm and at the same time natural rainfall willsupply enough water in most areas. However, they can be planted at any timewhen the ground is not frozen or waterlogged but in spring and summer youwill need to keep them watered for the first three months until the plant is established.
GROWING POTENTILLAS IN CONTAINERS
Potentillas can be grown in containers but they do best in the open ground. The shortervarieties make ideal rockery plants
POTENTILLA PESTS AND DISEASES
This section is almost not needed for potentillas because they very rarely suffer from any problems at all. If they are grown in water-logged conditions the roots can rot. The solution is not grow them in these conditions. If they get less than four hours of sunshine a day the flowering display will decline. If they are left totally unpruned for many years they may also fail to flower. In this case prune them back hard to a third of their size to rejuvenate them.
HOW TO PROPAGATE POTENTILLAS BY CUTTINGS
Potentillas grow most reliably from semi-ripe cuttings. The best time to do this is from July to August. Look for stems which have grown this year where the base of the stem is slightly woody but the top 10cm to 15cm (4in to 6in) is soft and green. The best stems will be at the top of the plant and fully exposed to the sun. Avoid taking cuttings from stems which have flowers on them.
Use a sharp knife to cut off a 10cm / 4in stem just below a
leaf node. Trim off lower leaves so that only four or so remain at the top. You can dip the base of the cutting in hormone rooting powder but this is entirely optional. Fill an 8cm /3in pot with multi-purpose compost and insert the cutting into it so that at least 3cm of the stem is in the compost. It can be inserted further but you don't want the leaves to touch the compost.
Water the pot from the base, insert a marker with the variety name and date the cutting was taken. Cover the pot with a plastic bag which is kept off the leaves. Keep the cuttings in a light place but not in direct sunlight. The bag should be removed after four weeks at which stage the cuttings will have begun to root. Keep the cutting in the same pot over winter in a light, frost free position such as a greenhouse or against a heated house wall.
In spring the next year, pot the plant up into a larger pot (15cm / 6in) and let it grow on. Keep well watered. In early September the potentilla can then be planted in its final position outside or into a larger pot.
GROWING POTENTILLA FROM SEED
Almost all the Potentilla fruticosa for sale nowadays are crosses betweenvarieties. The seeds will not come true to type and this is one of thereasons that they are not normally sold.
Another complication is that the flowers are dioecious. This means that eachflower is either female or male and that any individual plant will only produceall female or all male flowers. To produce viable seed you will need two plants,one producing female flowers and one producing male flowers.
Combining the two features above explains why producing new potentillas from seed is best left to the experts. The best method of producing new potentilla plants is from cuttings as described in the previous section.
DIFFERENT VARIETIES OF POTENTILLA
When choosing a variety of potentilla the two key difference to look for are size at maturity and the colour of the flowers. The list below shows some of the most popular varieties In alphabetic order.
Our recommended online supplier of potentillas is Crocus. The plants are sold in 2 litre pots to ensure they establish well. They give a five year guarantee.
Click here to see their selection of potentillas.
ABBOTSWOOD – has an RHS Award of Garden Merit. Height and spread 75cm / 2ft6in. White flowers over a longer than normal period of time.
DAYDAWN – our favourite potentilla because of the delicate shades of pink and yellow of the flowers. Height and spread 75cm / 2ft 6in.
GOLDFINGER – Golden yellow flowers which retain their bright colour even in full sun. This is a tall variety at 1.2m / 4ft and a spread of 75cm / 2ft 6in.
HOPLEY'S ORANGE – has an RHS Award of Garden Merit. Height and spread 75cm / 2ft 6in. Attractive yellow and orange flowers. A bushy variety.
PINK BEAUTY – one of the prettiest flowers, pink with white edges. Height and spread 75cm / 2ft 6in.
RED ACE – probably the the reddest of all the potentilla flowers with a yellow-gold centre. Height and spread of 60cm / 2ft. The flowers can fade to orange if in full sun.
MEDICINE WHEEL MOUNTAIN – has an RHS Award of Garden Merit. Height 30cm / 1ft spread 1m / 3ft. Deep yellow flowers, ideal as a rockery plant.
RED ROBIN – sometimes called Marian Red Robin, has an RHS Award of Garden Merit. Maximum height and spread of 1m / 3ft. Flowers start off as red but fade to orange if in full sun. A good variety for partial shade.
The GardenFocused approved online supplier of Potentilla Red Robin is Crocus. Click here to view their informative page about this variety.
WILLIAM ROLLINSON – has an RHS Award of Garden Merit. Height 60cm / 2ft, spread 45cm / 18 in. Semi-double red flowers.
Below we list the key strengths and weaknesses of Potentillas.
|No, partial, full sun
|POT / CONTAINER
|June to September
Other shrubs in this series include Camellias,
Choisya, Hebe, Skimmia, Mock Orange, Lilacs,
Rose of Sharon (hibiscus syriacus) all with pictures, full care and pruning instructions.
Sometimes our readers ask specific questions which are not covered in the main article above.Our new
Potentilla comment / question and answer page
lists their comments, questions and answers. At the end of that page there is also a form for you to submit any new question or comment you have.