As summer draws on we start to think about container gardening for colour in the winter garden. It is easy to be attracted by pansies and primroses; they are just appearing in garden centres and nurseries again after taking a break over the summer. Those cheery colourful blooms are appealing for the winter garden, especially as some of the summer bedding is starting to look pretty tired. Mini cyclamen are inviting too, their delicate reflexed blooms and attractive marbled leaves are somehow appropriate for the season. They are fine up until Christmas, in a sheltered situation, but soon suffer when the weather becomes more severe. There is no doubt about it flowers at this time of the year are at the mercy of the elements – foliage is more enduring for the winter garden, and can be even more colourful.
Recently Heucheras have rocketed to stardom, with new varieties being introduced all the time for fall foliage. Going back a few years the only heucheras found in gardens had small, rounded, rather hairy green leaves and fine stems carrying tiny red flowers in summer – hence the common name ‘Coral Flower’. The first purple-leaved heuchera that became popular was Heuchera ‘Palace Purple’, so called because it was reputedly used as ground cover under the roses at Buckingham Palace. This is still available, and it is a robust plant ideal as ground cover around deciduous shrubs. It is seed-raised so is variable in colour – often more of a muddy brown rather than rich purple, but do not let that put you off using it in the right place.
For more prominent positions in container gardening, such as pots-on-the-patio, modern heuchera hybrids excel for their range of fall foliage colours and leaf forms. In shades of green, purple, orange and copper their often waved and attractively shaped leaves make an eye catching display throughout the year and what is more they are evergreen. Their leaves usually look their best in autumn and remain in excellent condition throughout the winter months bringing colour to container gardening throughout the year. The hardier varieties are not one season wonders either; they will often last for several years before they become overcrowded in their pots.
The purple leaved varieties tend to be the hardiest and most robust. Heuchera ‘Plum Pudding’ is still one of the best with warm purple leaves, overlaid with silver on long leaf stalks. This variety is also one of the best for planting in the open ground where it will bring not just fall foliage - but year-round colour to the front of a bed or border. Heuchera ‘Licorice’ is darker in colour, almost black in winter, with more rounded shining leaves. Place it where it catches the light and it is certain to draw attention.
Some of the earlier orange and caramel leaved heucheras were of rather weak constitution. However selection and breeding has produced more robust varieties that are most striking for fall foliage in pots and this is the best way to use them. Their unusual foliage colour makes them difficult to place in the garden amongst green-leaved plants. They only really work when planted with gravel, or when combined with gold and brown sedges and grasses. In glazed or terracotta pots they can look stunning and are particularly useful partners for orange tulips when it comes to spring. The lovely Heuchera ‘Peach Flambe’ looks fabulous alongside a pot of soft orange tulip ‘Princes Irene’. Alternatively try the luscious caramel leaved ‘Creme Brulee’ alongside the scented tulip ‘Brown Sugar’, an altogether sweet concoction.
Heucheras can be hybridised with the closely related tiarellas to produce Heucherellas, excellent intergeneric hybrids. These are delicate, modest plants that grow well in shade and produce spikes of tiny green or white flowers. They make excellent ground cover and are generally hardy and easy to grow. Hybridisation produces some most attractive foliage effects; the leaves are more lobed and patterned than most heuchera hybrids. Heucherella ‘Sweet Tea’ is lovely with maple-like leaves of soft caramel and warm flame-orange. Heucherella ‘Tapestry’ is one of the finest with soft sage-green shiny leaves that are heavily marked and veined with dark brown. It has the advantage of producing quite showy small pink flowers in generous upright spikes. This would be an excellent choice for a pot that gets little winter sun, it would fit in well in any bed or border in semi shade too. Heucherella ‘Sunset’ may not be the most robust, but it’s a fantastic colour.
To grow heucheras for container gardening choose a loam based compost and provide plenty of drainage in the base of the container. Mulch the surface of the compost after planting with grit or gravel. This gives an attractive finish and keeps wet and soil off the foliage through winter. Next spring add a handful of controlled release fertiliser and work it into the surface of the compost to keep the plants in good condition. Regularly remove any dead leaves and faded flower stems to keep the plants looking good.
The main pest of heucheras is the vine weevil. You will know you have it if notches appear around the edge of the leaves; these are caused by the adult beetles. It is actually the larvae that do the real damage; these munch away at the roots. Vine weevil is easily controlled in pots by drenching the compost with Vine Weevil Killer, or a biological control applied in late spring or early autumn.