Noticeably shorter days, cooler conditions and the increased likelihood of rainy periods means that September is ideal for getting on with reshaping and replanting your garden before the full onset of autumn and winter.
On a practical level there’s a lot to be said for planting new areas, or adding plants to existing schemes, in early autumn because perennials in smaller pots establish well at this time of year. The advantages of this are manifold; buying smaller pots means that it’s possible to acquire them by mail order, from a myriad of remote nurseries, therefore having a wider choice of the best varieties; it’s better to buy multiple smaller plants, rather than one big one, because drifts and groups of plants are preferable to ‘dots’ of single specimens; small plants in small pots (especially if the pots are biodegradable) are more environmentally friendly, having used less resources to produce, than large specimens—even the weight saving has a bearing on energy use while being transported.
Digging up and dividing your own plants is, of course, even more cost effective and environmentally friendly. Whilst you are tidying up your borders you will naturally come across perennials, such as herbaceous geraniums, which have largely finished flowering and need to be cut back in order to prevent their exuberant foliage from squashing neighbouring plants. If they have produced a large clump it is also a good time to dig them up, chop up the large parent plant and produce numerous new plants. One can be planted back, with a handful of fertiliser, to carry on where the parent left off and the new plants can be directly planted elsewhere or potted up, using fresh compost, to either give away to friends or use to fill gaps at a later date.
On the subject of gaps in borders—now is the perfect time to plug them with spring flowering bulbs. Garden centres will be full of them, for a gratifying instant purchase, and there’s a certain pleasure to be gained by stuffing plump daffodil bulbs into brown paper bags. If you can forego that pleasure, and want the widest choice, then buying from mail order bulb firms—an internet search will reveal a huge choice—is recommended.
Take care to compare prices based on the size and quality of bulb supplied. Prices can vary greatly, with reduced rates available for buying in quantity, but sometimes what seems to be a bargain price is due to the supplier offering a smaller sized bulb. Obviously, comparing sizes is only relevant for the same species and variety of bulb, crocus bulbs will always be smaller than hyacinth bulbs, but for the exact same specimen it’s generally better to go for the largest size offered for a better guarantee of quality blooms.
Except for tulips, which should be planted into November to avoid ‘tulip fire’, the vast majority of bulb types are better off in the ground sooner rather than later. This is because the less time they spend out of the soil, having been dug up from their nursery fields, the better. They want to be sending roots out into garden soil while it is still warm. That way they can get properly established before the winter cold slows everything down. If you need to prioritise your planting then it’s a good idea to plant them in flowering order.
The exception here is that the very earliest flowering, the snowdrop, is best not bought as a dry bulb at all. This is due to the fact that snowdrops are so small that any bulb that was lifted many months ago, then stored until now, stands a high chance of having become completely dessicated and therefore ‘non-viable’ (a.k.a. dead). For this reason snowdrops are generally planted ‘in the green’ i.e. they are acquired in the spring as clumps of bulbs that have been dug up after flowering but which are still in leaf. This ensures that they are fresh and very much alive which offers the best chance of them establishing in your own garden
When planting spring flowering bulbs the general rule is that each bulb should be covered by soil to a depth of two to three times the size of the bulb itself. Common sense tells you that a tiny bulb will struggle if you plant it ‘six feet under’ but a great bruiser of a bulb, some daffodil varieties have huge bulbs, needs to be at least a trowel’s depth down. Take time over planting and remember to chuck a generous fistful of ‘fish, blood and bone’ over the bulb planting area. Firm the soil down well so that mice and voles are deterred from digging down and stealing your buried treasure!
Last month I made a passing reference to cutting back the long growths on wisteria—a plant which is almost invariably grown as a specimen trained onto a wall or over a pergola. Now is a good time to reduce excessive growth on any plants which are growing, trained or self-supporting, on walls or structures. Autumn winds and gales can dislodge whole established plants, sometimes taking their supporting structures with them, if they are not kept reasonably tight to the walls.
On a more positive note, when it comes to wall trained plants, there is a certain house I walk past, on occasion, which has a most surprising shrub trained against the front of it. The specimen in question is Callicarpa bodinieri var. giraldii ‘Profusion’ (the Beautyberry) which is generally grown as a free-standing shrub. It’s claim to fame is its almost unnaturally purple berries, borne in the autumn, because otherwise it is a fairly dull looking shrub. It’s an act of genius to tie it, it’s not self clinging, against a wall because it makes a startling display of purple, jewel-like, berries in a situation where it’s otherwise shapeless form is modified by being trained against a structure. Once seen, never forgotten.
Other timely tasks include: planting out winter bedding plants to give them a head start before temperatures start to drop. Similarly, autumn lawn care operations should be done now while it’s still warm enough to allow the use of ‘weed and feed’ treatments and for the successful establishment of new turf if making a completely new lawn or repairing an existing one.
Hedge cutting should be well underway now that the birds have stopped nesting and to give hedges the chance to re-clothe themselves before the properly cold weather is upon them. Preparing greenhouses, or other sheltering spaces, for the imminent overwintering of tender perennials is another task that’s worth completing ahead of any overnight frosts although, fingers crossed, we will have one of those, almost mythical, ‘Indian Summers’!
