There can be a bit of a gardening anti-climax in July. All the freshness of early spring, maturing into blowsy June, has passed and there is a danger that the vegetative growth, put on by shrubs and perennials, overwhelms the, less boisterous, plants which have yet to flower. Big, late, summer bloomers, such as Helianthus, Rudbeckia and the ‘back of the border’ Asters, can look after themselves; other border inhabitants may need some refereeing in order to cope.
Look at your borders and assess what has flowered, and may need ‘tidying up’, and what has yet to perform, and may need a little ‘freeing up’, if it is in danger of being swamped by neighbouring plants. However good you were at staking, or pea-sticking, plants at the beginning of the year, there will always be some that require a bit more propping up or tying-in.
Spring and early summer flowering shrubs can have their spent flowering shoots pruned out which maintains their shape and encourages them to produce a flush of new growth. The new growth is important because it is these vigorous shoots, maturing before leaf-fall, that produce the best flowers next year. Removing old shoots and excessive growth now has the advantage that you can properly assess just how big, and what shape, the shrub needs to be—something that isn’t always apparent when you are faced with an unruly mass of bare twigs in the winter.
Single-flowering, rambling / scrambling (as opposed to ‘climbing’), roses should also be subjected to this “cut out the spent – tie in the new” maintenance regime, just as if they were spring flowering shrubs. If the new, easily damaged, extension growths are not tied in there is a danger that they will get broken off, during wet and windy weather, or will whip around causing harm to neighbouring plants. The same rule applies to wisteria which should have the whippy growths shortened to half a dozen or so leaf joints and the faded flowers removed before the wisteria wastes too much energy attempting to set seed.
I find that Penstemons are invaluable for keeping a continuity of bloom from midsummer right through to autumn—even later in mild years. Being a relatively short-lived perennial, it is a prime candidate for propagating now by means of cuttings. In fact, it’s worth experimenting with cuttings from any slightly shrubby, semi-woody, plant at this point when hormone levels are high and their rooting potential at its greatest.
I use the same cuttings technique for practically everything in the garden although, if you invest in a good textbook on the subject, you will find many variations on the theme to fine tune the process. My simplification is to take non-flowering shoots, where possible, thick enough to withstand pushing into loose compost, and then to trim them up so that they are at least finger length, with a couple of leaves at the shoot tip, and denuded from the tip down. Always trim below the lowest leaf joint with a sharp knife, preferably a craft blade, and additionally reduce the remaining leaves too if they are over large.
The reason for removing most of the foliage is to reduce water loss from the cutting because, until it has grown roots, water lost via leaves cannot be replaced by water taken up by roots. This is the same reason why (see later) it is necessary to keep a humid atmosphere around the cuttings. The cuttings are inserted into moist compost, I use a multipurpose compost with added 50% grit / perlite to keep the mixture ‘open’ i.e. aerated and free draining. When filling the pot, take care to ensure that the compost mix is only lightly firmed down, not rammed hard, to ensure that there is still plenty of air left in it and it stays ‘sweet’.
The cuttings are inserted around the outside of the pot, rooting tends to be quicker at the edge of the pot rather than in the middle, and waterer in well using a fine rose fitted to a small watering can. Finally, to maintain a humid atmosphere around the cuttings, place a polythene bag over the whole ensemble and tie at the top. A length of cane pushed into the centre of the pot keeps the bag off the cuttings and gives you something to tie against.
Tender perennials propagated at this time of year should root readily, under their own steam, but hormone rooting powder may assist in slower rooting specimens and can guard against rotting as it also contains fungicide. Place somewhere inside, such as a light windowsill, but not somewhere where they will roast in the sun.
Also on the ‘propagation of plants’ subject; you have up until the end of this month, preferably sooner, to sow biennials for flowering next year. There seems to have been a real resurgence of interest in these ‘old-fashioned’, cottage garden, style plants on the back of trends for ‘cutting gardens’ and home-grown bouquets. You can’t beat pots full of ‘Sweet William’, ‘Honesty’ and ‘Sweet Rocket’—somehow it seems wrong to use Latin nomenclature here—even their names conjure up scenes of scented floral perfection!
Elsewhere in the garden, regular maintenance will be continuing unabated; lawns need mowing, containers need watering and ‘high performance’ bloomers like to be dead-headed and well fed…
Dead-heading of bedding and container plants is essential to keep them flowering right up until the frosts. Adding fertiliser to the watering can, at every other watering, also keeps them performing to the best of their ability. Similarly, dead-heading roses, plus giving them a dose of rose fertiliser forked in around their roots, aids blooming while maintaining healthy growth to maximise flowering potential for next year.
We seem to be having (tempting fate here) a reasonably warm and dry summer, so far. Target your watering only to those plants that really need it, primarily the newly planted and those in containers i.e. without access to ‘true’ garden soil. Resist the urge to use wholesale ‘sprinklers on the lawn’; brown grass always greens up again when the rains return. And, if I’ve learned nothing else (tempting fate again) it’s that, here in West Dorset, the rain will always return!!!