The Spiraea group of shrubs is very popular - not without good reason. All of the Spiraeas mentioned here are quite hardy and flower regardless of weather conditions. Most of the garden Spiraea shrubs are deciduous – some with colourful foliage; all with masses of showy flowers in a range of colours from the purest of white to deep red.
The individual flowers are small saucer or bowl-shaped flowers. Grouped together in racemes the flowers never fail to make a good show. They are particularly welcome for the early flowering display – just as the foliage starts to break through after the winter dormancy.
Spiraeas include all the popular sizes required of garden shrubs - some small and compact, whilst others are more suited to the back of shrub borders. There will be a Spiraea for any but the most hostile of areas. Spiraeas – members of the wide Rosaceae family – are all easy to grow and require minimum maintenance throughout the gardening year.
Foliage colour on some varieties is the dominant feature – notably the pink and red flowering types that have variegated or gold foliage. One thing that is often overlooked and understated is the fact that more or less the entire Spiraea group has good autumn colour foliage.
The popularity of Spiraeas has been helped with some of the well-descriptive common names – such as ‘Bridal wreath’, Spiraea japonica ‘Goldflame' and ‘Snowmound’. If only the gardening trade were to latch on to this, it would help to popularize gardening and more importantly, make it a little more ‘user friendly’.
All of the Spiraeas mentioned here are fully hardy – as you would expect from plants whose natural home are the Northern regions of Europe, Asia and N. America. As well as the virtue of hardiness, most are trouble and maintenance free, other than a few that get beset with powdery mildew. That is particularly annoying for the ones affected by mildew tend to be those varieties that are grown mostly for their foliage effect!
Any soil that is well drained – preferably moist – which includes a wide range of ph levels to be tolerated. I have grown most varieties on chalk downs of Kent, and also acidic soils more suited to rhododendrons and the like.
All of the Spiraea shrubs are happiest in full sun, though a little dappled shade will be tolerated. An open aspect without too much concern about exposure to the elements makes them a good choice for sunny banks, hedges, general landscape plantings and of course shrub borders. Some of the smaller varieties are not out of place in the rock garden even. In short, if you have a situation where you would like an additional shrub, consider one of the Spiraeas.
Most Spiraeas flower in either late spring or very early summer, which basically means that any pruning should be carried out right after flowering.
Spiraeas are also known for herbal medicinal purposes and contain a range of chemical substances such as salicylates, which is one of the forerunners to the discovery of Aspirin.