Five steps to put your garden in holiday mode

Summer holidays beckon in this year of ups and downs. If you have been distracted by parties, invitations and transporting children, what should you do in the garden before you leave it to itself for a fortnight? I will assume it is fairly new to you, not big but, in principle, well loved. Here are five points for attention, followed by a suggestion for improving it in future.

First up, as ever, are weeds. Do not be seduced by the recent rhetoric in their favour. There are excellent reasons for removing them, especially if you want a varied garden with flowers and interest throughout the year. They compete for water with prettier plants. Some of them are so invasive they crowd out lovelier neighbours. They look a mess and even if you like a messy look they are not as lovely as better-behaved messies. Public hype for weeds, “plants in the wrong place”, is nothing new. It has been audible for as long as I have written this column.

In the past 10 years it has become entwined with saving the planet, fostering pollinators and “rewilding”. Some ivy on a boundary fence and some strategically permitted nettles may encourage overwintering butterflies to breed in your garden but, believe me, a veteran of these attempts, much depends on the unpredictable appeal of competing attractions, especially in cities.

As for pollinators, they head for foreign beauties, tended in a garden, and wriggle into them busily. Last month, I took a group of Oxford undergraduates round our college gardens and emphasised this fact beside the fine white-flowered shrub Deutzia monbeigii, which I recommend. At 6.30pm on a sunny evening its flowers were teeming with bumble bees. It is at home in China and was introduced from Yunnan.

For a pre-holiday clean-up, go on the prowl for weeds that are flowering or about to seed. Root them out or at least decapitate them before they seed fully in your absence. Look especially for pale-pink willowherbs, easily pulled up, thistles of all kinds and chickweed, which comes out in a trice. Grasp the thistles near ground level to be sure they come out fully. Do not become obsessed with digging up bindweed or ground elder: attack them on your return but, meanwhile, pull off any accessible stems of bindweed and ensure that there are no flower heads, like white parasols, on ground elder.

Take a bag so that weeds with seed heads can be decapitated directly into it before you shake their stems and scatter their seeds while pulling up the plants. Remember the old truth: “One year’s seeding, seven years’ weeding.” It will spur you to repeat the prowl about 15 minutes later. First time round we all miss major candidates for extraction, so a second prowl is essential.

After deseeding weeds, concentrate on the front rows of a border or big flowerbed. On your return you will be happy to see signs of recent order and control. If the fronts are tidy with a neat edge, disorder in the middle to back rows is less disconcerting. Weed all the fronts round the garden, rather than weeding one bed fully.

Next, cut down perennial plants that have passed their flower-by date. The priorities here are hardy perennial geraniums, except the admirable Rozanne and its lookalikes, which will continue to send up blue flowers. I had superb displays on the pale-blue geranium Blue Cloud, which I strongly recommend, but now all its top growth needs to be removed, leaving only the basic cluster of leaves at ground level. Johnson’s Blue, all varieties of Geranium pratense, the meadow geranium and the magenta-flowered psilostemon need the same treatment. So do foxgloves, early verbascums and blue-and-white Campanula persicifolia, leaving one or two stems to seed haphazardly for future years.

Next, pruning. Two priorities guide me here: roses and wisteria. There is no point in deadheading the vigorous rambling roses I recently revisited: they flower only once. Sort your roses into those that have second flowerings in September and clip the dead flowers back to the first pair of leaves below. On a charmed evening at Sissinghurst, in his mother Vita Sackville-West’s marvellous rose garden, Nigel Nicolson once complained to me that the National Trust gardeners had left deadheads on the rosebushes “like dirty handkerchiefs”: as none of the old varieties would flower a second time the job was not a top priority.

Take a bag so that weeds with seed heads can be decapitated directly into it before you shake their stems and scatter their seeds while pulling up the plants

In her new poem, “Was It For This”, prize-winning poet Hannah Sullivan refers to the roses in her London garden as looking like “a pinched pair of tea bags stuck to a spoon”. I thought she meant fully flowering roses and chided her but I forgot they were “crisped up” and she silenced me with a photo of her recent deadheads looking decidedly like post-cup Earl Grey bags. Cut the tea bags off twice-flowering rosebushes before you leave, thereby encouraging a good second flowering.

Since June, wisterias have sent out thin, green stems that wave free of a wall or arch. Prune them off too, keeping in mind the image of a well-pruned or spurred vine in a vineyard, cut back to its hard older growth and checked from becoming too green and sprawly. Wisterias flower better next year if they are stopped from flying now in all directions. If you have a rambling rose, also free with new growth, cut all that growth off too, concentrating it to a solid framework of stems from which it will flower next year too.

Fourth, soak and feed. Even if there has been rain, spend time watering everything in pots or other containers until water runs from the holes in their flat underside. Usually, densely planted pots are under-watered, being wet only for the first few inches of their ball of soil. As you will be away, give them each a long steady watering now, not just a spray with a hose on a high pressure. They are more likely to hold well until you return.

When they are wet, give diluted fertiliser from a full can of water, using Tomorite, the cheap tomato fertiliser, on dahlias and other free-flowering bigger plants. For petunias and smaller bedding plants I use Phostrogen in a powdered, dilutable form. Feeds will last a fortnight, needing to be repeated just as you return. Feeding distinguishes expert plantings in pots from those of part-time gardeners, attending as best they can. Begonias love it.

Last, an idea for next year. I owe it to my elder brother, a shrewd gardener: all along the narrow gap between his front paving and his lawn he has planted alpine strawberries from seed. They look wonderful and have been holding their small, distinctively flavoured fruits since early June. They never appear among strawberries, gas-cooled, in supermarkets, but in glasses, with cream, blueberries and a dash of lemon, they are unrivalled. I recommend Alpine strawberry Mignonette from Thompson and Morgan, at £2.99 for a packet of 320. Seed is fine and should be sown and covered very lightly with vermiculite or damp sharp sand in September. Alpine strawberries are a project to look forward to on your return.

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Letter in response to this column:

Cross-pollination of ideas / From Kevan A C Martin, Witney, Oxfordshire, UK