What does one do in the garden in June? Sit back and enjoy it, perhaps - and who wouldn’t, if we’d had some decent weather lately! Hopefully plantings from earlier in the year have nonetheless taken off, your lawn will be looking decently green (given the amount of rain we’ve endured during the last months), and your veg will be doing their appropriate thing.
However, it certainly can’t just be the time to let your plot look after itself. In spite of all that rain, regular watering is essential, especially of plants in pots. Should you have hanging baskets this should be done every day. Permanent plantings in pots will benefit from regular feeding throughout the growing season, so putting something like Phostrogen or Growmore soluble plant food in your watering cans is a good idea (Camellias and similar lime-haters should have a specialist feed).
It would seem to be “a good year” for roses. Most modern forms, including climbers, should, of course, have been pruned in the spring, but, if you have any once-flowering ramblers, old-style shrub roses, species roses, or other old rose types, these should be pruned after flowering, which will probably be towards the end of this month, or maybe as late as July (there is an excellent guide to rose pruning on the RHS web-site: https://www.rhs.org.uk/plants/roses/pruning-guide). If you like the graceful flowers of old roses compared to modern hybrid teas and floribundas, I recommend hybrid perpetuals, which flower twice in the season, or sometimes throughout the summer and well into autumn (I highly recommend this rose grower: https://www.trevorwhiteroses.co.uk/product-category/hybrid-perpetual-roses/).
Talking of summer pruning, this month is the proper time to deal with early-flowering shrubs, rather than the spring – shrubs in flower in May or June do so on wood that matured last year, so should be left alone till they’ve finished flowering. One of the most common shrubs to be given the wrong treatment in this regard is Philadelphus (mock orange). The gardens of England are cluttered with misshapen specimens of this beautiful bush, so often butchered in spring for the sake of a general “tidy up”. “Oh, it never flowers!” is the cry … it’s hardly the plant’s fault that the said tidy up removes all its flowering material.
Dead-heading is really another sort of pruning. It can be time-consuming, but does extend the flowering time of many plants. This especially applies to your summer bedding, most of which is annual, desperate to flower, set seed, and, having fulfilled its purpose in life, to die as soon as possible. If you don’t let it go to seed, it has to keep flowering.
With any luck June will at last see some real summer weather, which, as well as flowers and vegetables, brings on hordes of pests. Nowadays we are rightly encouraged to limit the use of pesticides, but I do make an exception when dealing with lily beetle, an absolute menace. They are said to be less troublesome to pot-grown specimens, but I still find it necessary to spray against them now and again (growing them in pots should also reduce the spread of any spray used). These handsome beetles also do ‘orrible things to now-fashionable agapanthus and other members of the Liliaceae family, so it really is worth doing this. Here I also repeat earlier comments about vine weevil: their larvae can absolutely devastate potted plants, so using a weevil-killing chemical twice during the summer is, I think, important (Evenlode DIY stock a wide range of useful bug-killing preparations).
In your vegetable plot and greenhouse, now is the time to pinch out sideshoots on your tomatoes (is anyone growing “Crimson Crush”? It comes with high accolades for blight resistance and flavour.) Also, you should soon be able to harvest early potatoes, lettuce, radishes, and other salad crops. If it does get hot, remember to shade your greenhouse and be careful to ventilate it sufficiently (another excellent page from the RHS site: https://www.rhs.org.uk/garden-features/ventilation-and-shading-greenhouses).