Summer solstice, a time for change
Spray runner beans with water to increase flower set
Alstroemeria 'Rock and Roll'
So the days are getting shorter, sorry to say that, but on the bright side the height of summer is yet to come. In the garden we are moving through a transition phase where the woody plants, trees and shrubs, are slowing in their growth and begining to lignify. This is the process of hardening off the soft spring growth into a rigid woody structure [preparing for winter!] and the ripening of as yet hidden flower buds for a display next spring and early summer. That effectively means the plant stops growing and puts its energy into that part of its yearly life cycle.
This is the reason we prune, if necessary, the spring and early summer flowering shrubs immediately after they have flowered. So they can make up new growth that still has summer time to lignify and set flower bud to give us a display the following year. If you prune these plants in autumn, winter or spring you will effectively be cutting off that years flowers.
Shrubs like Forsythia, Ribes and Kerria that flower in spring should have been well pruned by now. Later flowerers like Choisya, Cistus and Genista will have been pruned quite recently. Neither groups should be effected in respect to their flowering profusion next year. This is not always the case with the mid summer flowerers.
Plants like Philadelphus, Weigelia and Deutzia that still flower on old or last years growth rather than on new or this years growth. This mean in our climate the pruning of these plant after flowering may not give the plant sufficiant time to recover and form new flowering wood. Hence reduce or deny you of flowers completely the following year.
Only prune June flowering shrubs if they really need it and most of the time you'll find that they don't. That generally applies to all flowering shrubs up to July don't prune unless they are to big for their space or have become unruly. Even then try to thin out rather tahn assault with shears over the complete plant.
There is of course, just to be awkward, an exception and that is with the genus Cistus which can become very leggy and straggly in a few years. With Cistus I do prune annually with shears but only back as far as living growth, this should give you a compact plant that flowers better and lives longer.
Many shrubs that flower after or during July tend to flower on the new growth that has occured during spring and early summer. Plants like Buddleja, Fuchsia, Abelia and Hypericum fall into this category. Pruning these anytime during autumn, winter or spring does effect their flowering performance. In fact it can actually enhance it as the hard pruning of Buddleja and fuchsia tends to lead to more flower. Hard pruning of Hypericum and Abelia species may result in no flowers however and these should be treated with slightly more sympathy.
With summer equinox past and many shrubs fading into the backdrop of the garden we can look forward to the rise of the herbaceous perennial. Many have already or are about to make a welcome return to our borders. Most, with a little deadheading, will keep flowering right through the rest of the summer months into autumn. Penstemons, Anthemis, Rudbeckia, Gaura and Phygelius would be amongst these.
Other herbaceous plants like Agapanthus and many Geraniums tend to flower once over a month period. There are newer varieties of Agapanthus like 'Blue Storm', 'Snow Storm' and our Wexford bred 'Agapanthus 'Kilmurry White' and 'Kilmurry Blue' that flower over a much longer time. The marvlous Geranium 'Rozanne' will flower from June until first frosts. Astronomically the summer solstice is the begining of summer , Hurrah to that. So not the begining of the end perhaps but the start of the begining.