Groundcover perennials such as geraniums, catmint and alchemilla that look like they have breathed their last will not only perk up after a radical shearing but could well flower once more; encourage them with a dose of dilute liquid seaweed.
© Gap photos/Friedrich Strauss
When lavender, santolina, helichrysum and other Mediterranean plants have bloomed, don't just cut off the faded flower stems — a fiddly job — but get creative, and snip the grey or silvery foliage into rounded, sculptural cushions that give them a whole new urban edge. Check out what's looking good at the garden centre and prepare to pot, because baked clay is not a good environment for bringing up baby.
© Gap photos/Friedrich Strauss
Forget the current fad for native plants — at this time of year, big and bold, not small and dainty, are the statement plants that will revive, at a stroke, flagging borders and lacklustre patios.
Look to the exotics for real impact: scarlet cannas with dot-and-dash foliage, sky blue agapanthus, citrus-shaded lilies, red banana Ensete Maurelii with huge paddle leaves that gleam like stained glass in the late, low sun. Use them to fill gaps in the border, keeping them in their unobtrusive, blend-into-the-background black plastic pots. You can then simply lift them out when summer's at an end and store them over winter.
Where a plant is planned for the front line, re-pot it in terracotta or a glamorous glazed pot, so it looks intentional. Several uniformly glazed pots, randomly spaced along the front of a border and planted with eye-catching dahlias in jewel-bright shades, will brighten the landscape immeasurably.
If you can bag one, it's worth spending on a brugmansia dripping with trumpet flowers that you can plonk centre stage on the patio to divert the eye from less attractive views. It will also provide fabulous evening perfume for alfresco dining.
The contrasting colours and textures of sempervivums — find them in the alpines section of the garden centre — make marvellous rosette mosaics in wide, low, terracotta bowls that are ideal for lining garden steps or decorating the terrace table. Needing no water, they make the perfect home-alone plant for worry-free weekends away and even three-week vacations.
© Gap photos/Christa Brand
Plants in pots will need less watering — and look their best — if the compost is given a coverlet of gravel; pebbles, if the plant is large.
You can't water the entire garden, unless you have an irrigation system to do it for you, so concentrate on the young and vulnerable — newly established shrubs and trees, container plants and vegetables — making sure you reach the roots rather than just ineffectively sprinkling the canopy of foliage. As a guide, if you planted anything later than April, you can't expect it to thrive with no watering through summer.
If you have more than a score or so of small pots on the patio, this might be the time to remind yourself that half a dozen large pots of multiple plantings are easier to water, look more effective and are less likely to perish if neglected for a day or so.
Leave the lawn. However brown and scrappy the grass looks now, it will go green once more, so turn a blind eye and hold back on a weed-and-feed rescue package until autumn.
As we know, watering first or last thing is preferable to watering in the middle of the day — but busy Londoners water when they can, and far better to water in strong sunlight than not to water at all.