Bordering on great!
HERE is something quite satisfying about not being able to cut down the border in the autumn because the plants are still looking so good. This is certainly the case at Aberglasney this year as much of the garden is still looking fantastic and there is plenty of long lasting colour. Asters are one of the best plants for the autumn and there is a huge choice available. They often have many different uses and this is mainly due to the range of colours and heights we can work with.
Their main use is as an herbaceous border plant and depending on height they can be planted in the front middle or back of the border. Many will do well in small spaces or rock gardens and some do well in large scale plantings or even prairie type planting. They are generally easy to grow, other than the novae-belgii type which sometimes gets powdery mildew. We grow around 20 different varieties at Aberglasney and have not had any problems with mildew even on the novae-belgii type.
Asters generally do best in sunny positions, although with extra care they will cope with some shade. Most of our plants grow in west facing positions in the walled gardens where they do absolutely fine. Most of the varieties require little staking and are cut back once a year which is about all the care they need. Generally we don't mulch over the crowns of Asters. We find they do better by mulching around them. They seem to do well on most soils, although they struggle in water logged soil. Many of the Asters really thrive on alkaline soil but seem to do fine in our neural soil too. If they are struggling, adding some lime will be a great help to them.
The dwarf varieties of Aster make especially good garden plants. We have been particularly pleased with Aster 'Little Man in Blue' which is full of flower at the moment. The dwarf or short varieties of Aster are useful too as they fill gaps between other perennials and disguise the plants that have been cut back. We find they mix really well with Kniphofia, Geranium and Helenium which all flower earlier in the season.
A good medium sized Aster is Aster amellus 'King George' which has very large flowers and can need some help to stand up. This type makes a good middle of the border plants and again mixes well with other perennials. 'King George' also seems to start to flower a little earlier than many of the other Asters which can be good thing.
The taller varieties make excellent back of the border plants and there are plenty to choose from. A good white variety is 'Kristina' which is in flower now. The taller varieties look good with late flowering Phlox and other tall perennials. We grow blue varieties next to white Phlox and they look really good. The trick is to 'Chelsea chop' some of the Phlox so that you are guaranteed some late flowers.
There are also some more unusual Aster that grow in shade, such as Aster divaricatus which has white flowers and really brightens up dark corners. There are some specialist types such as Aster soulei which are ideal for rock gardens in sunny spots. However one of the best uses for Aster is to have a large number in a long border where they will give an excellent autumn display. Either way they are really useful garden plants and can brighten up the autumn.