The Garden in September 2024- ‘Into the Autumn’
September, of course, sees the beginning of autumn but in many ways it is also a continuation of summer with its often warm and sunny days. In the garden it is a time when the late summer flowers are joined by the autumn specialists for a glorious display of rich colours as we approach the end of the growing season for another year.
Looking back through past blogs I see that in 2020 I was writing about the lovely September flowers that were growing in our garden at that time, planting container grown plants and working on the lawn. In 2021 the blog looked at the gardens at Aberglasney in all their September splendour. In 2022 I highlighted Japanese Anemones, Asters, Rudbeckias and ornamental grasses as well as taking a look at spring bulbs and other food storage organs such as corms, tubers, rhizomes and stolons. In September 2023 I was looking forward to autumn and winter and recommending a whole range of plants from trees, shrubs, climbers and perennials which can provide interest in the garden through those seasons.
As for as my ‘five plants for September which I wouldn’t want to be without’, I’m afraid that you will have heard me sing their praises many times before because they really are that good! I simply can’t imagine September without Asters/Symphiotrichons, Sedums, Rudbeckias, Japanese Anemones and ornamental grasses but I would also like to add another, less well-known plant which is flowering beautifully for Teresa and I at the moment- Pheasant Berry or Himalayan Honeysuckle (Leycesteria formosa).
No doubt, like me, most gardeners get confused at some time over the naming of plants. Partly this is because most plants have two names- a, or a number of, common names as well as a botanical name and partly because the botanical name is in Latin and made up of at least two different types of name! Common names which mostly date back to the time the plant was first known or cultivated can be very useful to gardeners in that they are generally descriptive of the plant and make sense to many people when referring to plants. However, the common name is naturally in the language of that country and means little, if anything, to a person with a different language. Also, the common name gives limited information about the plant and certainly does not uniquely identify it. For these reasons in the 18th century the Swedish botanist Carl Linnaeus devised a scientific method of naming plants by giving them botanical names in a language common to many countries at that time-Latin! These are now recognised in all countries and uniquely identify every plant as well as identifying relationships between plants so that ones with similar ancestry can be traced. Botanical names are made up of at least two parts- a GENUS name (plural Genera) and a SPECIES name. For example, Papaver orientalis is a type of Poppy- Papaver is the genus name which always start with a capital letter and orientalis is the species name which always start with a small letter and it is normal practice to write them both in italics. The genus name represents a group of plants with similar characteristics and in evolutionary terms represent a common ancestor for all the plants in the genus. The species name represents a sub-group of one or more plants within the genus which again have similar characteristics. There can be a large number of species within a genus, for example the Quercus genus (oaks) contains over 450 species. One important characteristic of plants within the same species is that they can reproduce with each other. Despite being in Latin these names can tell gardeners a good deal about the plant in question. Many genus names such as Clematis, Hydrangea and Phlox are the same as the English common names and species names, many of which are used in some form in the English language, can also provide useful information about plants such as:-
Colour- alba (white), aureus (gold), cyaneus (blue), nigra (black), purpurea (purple)
Habitat- alpinus (alpine), campestre (field), montana (mountain), pratense (meadow), sylvestris (forest), saxitile (rock)
Countries/regions- arabis (Arabia), chinensis (China), japonica (Japan), occidentalis (America), orientalis (Orient/Far East), sibirica (Siberia)
Growth habit- columnaris (columnar), cupressa (closely packed), dentata (toothed), fruiticosa (bushy), lanata (woolly), repens (creeping)
This method of naming plants is referred to as the binomial method because of the use of two names. However, in some cases in the naming of plants just two names are not enough to uniquely identify a plant and I will go on to look at the additional names used next month.
September is the start of the spring bulb planting season of which I have written several times. In the blog of September 2022 I looked at the various types of food storage organs including bulbs and the roles these plants, with their colours, forms, fragrance and foliage, can play in any planting scheme such as bold patterns in formal beds, seasonal interest within mixed borders, splashes of colour in containers and sweeping carpets beneath trees or shrubs or in grass. In August 2023 I highlighted some of the less well-known spring bulbs including, from the early flowering group, the Spring Snowflake (Leucojum vernum), Scilla, Chionodoxa (Glory of the Snow), and from the late flowering group, Camassia. This blog also went on to consider other spring flowering plants such as Forget-me-not, Wallflower, Bellis, Primula, early flowering perennials such as Doronicum and Pulmonaria, early flowering shrubs such as Daphne, Corylopsis and Cytisus, early flowering climbers such as some Clematis and Honeysuckles and finally a great spring flowering tree- Amelanchier, the Snowy Mespilus. Going back to the spring bulbs, there are so many to choose from and with their different flowering times it is possible to have flower colour from January right through to April/May. They are also so easy to plant between September and October with just Tulips a little later in November to avoid the fungal disease of Tulip Fire. Just make sure that they are planted deeply enough so that they have the best chance of flowering for several years to come. The general rule is to cover the bulbs with soil or compost which is twice as deep as the height of the bulb. Then just sit back and wait for nature to work its miracles for a great spring display.
Back onto the subject of taking cuttings which we started in March, we are approaching the best time to take root cuttings. These are taken in the plants’ dormant season ie. late autumn and early winter from young, vigorous roots of around pencil thickness. The technique can be used to propagate mainly herbaceous perennials and alpines but also a few trees and shrubs. In terms of perennials, it is a particularly good method for plants which have fairly thick, fleshy roots such as Acanthus, Verbascum and Papaver orientale cultivars. Once dormant the whole plant can be lifted, the roots washed and one or two young roots cut off close to the crown of the plant which can then be replanted, possibly after division, or discarded if too old and past its best. The selected roots can then be cut into sections after removing any fibrous roots, each between 2-4”/5-10cms long with a straight cut at the upper end of the cutting and a slanting cut at the bottom end so that the cutting can be inserted the right way up. Shoots will eventually grow from the top and roots from the bottom. The cuttings need to be inserted vertically into a potting mix of half peat-free compost and half perlite, vermiculite or grit in pots or trays the depth of which are at least one and a half times the length of the cutting with the top of the cutting level with the compost surface. The surface of the compost can then be covered with a thin layer of sand or grit and placed in a propagator in a cold frame or greenhouse. Some perennials such as Anemone hupehensis and A. x hybrida, Campanula, Phlox and Primula denticulata and vulgaris often have roots which are too thin to insert vertically and these can be cut a little longer at 3-5”/7-12cm to give them sufficient food storage and then laid horizontally in trays of firmed compost and covered by a little more compost.
As we approach the season of more intense storms it is a good idea, particularly in exposed areas, to prune established climbing roses to prevent wind damage over the autumn and winter period. The main stems can be left unpruned unless they exceeding their allotted space in which case they can be shortened to fit their supporting structure. These and any young shoots which are required to become main stems in the future then need to be tied in securely to that structure. The side shoots from all these main stems can then be shortened to around 6-12”/15-30cm from the main stems. These side shoots can be lightly pruned again in the spring to 3 or 4 strong buds to remove any winter damage or dieback and it is these buds which will produce the shoots which will carry the flowers for that season.
Autumn is also a good time to give the lawn some attention before the winter wet sets in as it is sure to do at some stage! The lawn can be scarified and/or aerated particularly if these tasks were not carried out in the spring. Scarification removes dead grass (thatch) and aeration helps to improve drainage and aids deeper root growth by reducing soil compaction as discussed in more detail in the April 2024 blog. Early autumn is also the time to apply an autumn fertiliser to the lawn to help root growth and make the grass more resistant to the weather to come. Such fertilisers have lower nitrogen and higher potassium and phosphate contents than spring and summer fertilisers for root growth rather than top growth. For best quality lawns autumn is also the time when top dressing can be carried out once all the other lawn work has been done. The dressing is a mixture of sand, sieved top soil and a peat-free compost and is best applied on a dry day and then brushed into the surface so as not to smother the grass. Finally, throughout the autumn as leaves fall it is important to rake them off the lawn from time to time so that they do not sit on the grass for long periods causing it to yellow. Small amounts of leaves can go into the compost bin and larger amounts into black bags to eventually rot down and produce ‘black gold’-leaf mould!
That’s all for this month but I will be back with an October blog and for the final talk of the year on Saturday October 5th. For those of you reading this in early September there is also the free September talk at the Old Railway Line on Saturday 7th in the Wild Bird area starting at 10am when I will be looking at some great September plants, discussing the main points of this blog and attempting to answer any questions which come up on the day. For October I shall be choosing my five plants for that month that I wouldn’t want to be without and looking at topics including the second part on plant names, taking hardwood cuttings, planting bare root trees and shrubs and making leaf mould.
Until then keep well and enjoy your autumn gardens.
Keith.