Since creating a meadow area in his own back garden three years ago, Sir David Attenborough has enjoyed an influx of wildlife and is this year hoping to see a wide range of butterflies visiting it.

"I have an area of meadow turf with a mown lawn walkway which winds its way through it and I see a number of different butterflies - meadow browns, cabbage whites and occasionally tortoiseshells. I haven't seen a red admiral for a number of years though, but I used to."

As president of the charity Butterfly Conservation, Sir David will be taking part in this year's Big Butterfly Count, in which members of the public are asked to report sightings to give the charity a clearer picture of the nation's butterflies. This, in turn, gives us a view of the state of the countryside as a whole.

Garden favourite, the small tortoiseshell enjoyed its best year for a decade last summer, while peacocks, small and large white also had good years, but migrants including red admirals and painted lady struggled.

"The count helps us a great deal," says Sir David. "It provides a recognition chart from a scientifically accurate, huge army of observers whose results can give you all kinds of important information.

"What we know is that last year was a good year for butterflies in that a lot of species came back or increased in numbers, but the decline in British butterflies is still going on. Last year was an optimistic blip."

Three quarters of the UK's butterflies are in decline and one third are in danger of extinction, according to the charity.

"This is bad news for butterflies and it is bad news for the UK's birds, bees, bats and other wildlife. Butterflies are a key indicator species of the health of our environment - if they are struggling, then many other species are struggling also," says Sir David.

"Butterflies are pollinators, pollinating the countryside. To have pollinators in the countryside means you have a healthy and renewing countryside. If you lose them, you will lose a great deal."

Butterfly numbers have declined because the numbers of wild places left in the countryside have diminished as agriculture has become more efficient, he says.

"But if you put together all our suburban gardens, they form a huge area in the British landscape and they can help replace those wild places that agriculture has taken over."

He says gardeners can all do their bit to help butterflies.

"Gardeners can take a small patch of their cultivated, cosseted garden to go wild. You may not like nettles or brambles, but they provide food for quite a range of butterflies."

Plants including buddleia, Verbena bonariensis, lavender, perennial wallflowers and marjoram are all magnets for butterflies. Other plants which attract them include hebes, Michaelmas daisies, cosmos, phlox, pinks and heleniums.

Choose sunny, sheltered spots to plant nectar-rich flowers and try to provide flowers right through the butterfly season. Spring flowers are vital for butterflies coming out of hibernation while autumn flowers help butterflies build up their reserves for winter.

UK butterflies rallied last summer following their worst year on record but numbers were still below average.

Dr Tom Brereton, head of monitoring at Butterfly Conservation, says: "The recovery of butterflies in 2013 was highly welcome but there is still a long way to go before butterflies return to former glories.

"Our ongoing monitoring efforts will be vital in assessing whether we are on track to reverse butterfly declines and rebuild a healthy countryside."

:: The Big Butterfly Count runs from Saturday, July 19 to Sunday, August 10. For information and help with identifying butterfly types visit www.bigbutterflycount.org

BEST OF THE BUNCH - SALVIA

A plant loved by landscapers and novice gardeners alike for its colour and structure, the salvia is the Horticultural Trades Association's Plant of the Month for July.

Available in both annual and perennial varieties, the salvia is a member of the sage family and comes in various shades of colour - red, cream, purple and pink.

The intense flower colours of hardy salvias make them suitable for creating a focal point in borders. Salvias are long flowering, with the potential to put on a great show through much of the summer and into autumn. Remove the flower spikes as soon as they have faded - you can often enjoy a second flush of flowers in October.

Grow them in full sun in well-drained and moderately fertile soil. Deadhead any flowers and trim in late spring any shoots that spoil symmetry. Good Varieties include Salvia 'Hot Lips', S. nemerosa 'Ostfriesland' and the dark indigo S. x sylvestris 'Mainacht'.

GOOD ENOUGH TO EAT - GROWING RASPBERRIES

There's nothing like the intense flavour of home-grown raspberries in summer, which are always expensive to buy in the shops but pretty easy to grow yourself.

Raspberry canes need support such as a post and wire system, so you can train them easily. They should be planted in fertile, well-drained soil with plenty of well-rotted manure or compost in a sheltered spot that gets sun for at least half the day.

Summer-fruiting varieties should be planted in autumn through to winter 45cm (18in) apart in the row, with 1.8m (6ft) between rows. In spring, mulch with well-rotted organic matter and they will later need feeding with general purpose fertiliser.

Keep them well watered when the fruits are swelling and protect the ripening raspberries from birds by covering the rows of canes with netting.

If you want to lengthen the season, plant some autumn-fruiting varieties as well, which start ripening in late August through till the first frosts.

WHAT TO DO THIS WEEK

:: Reduce the lengths of wisteria tendrils by half.

:: Water dahlias regularly and feed fortnightly, paying attention to young plants which are slow to grow.

:: Harvest fruit, vegetables and herbs while they are in prime condition.

:: Peg down runners on strawberry plants that you want to propagate.

:: Transplant wallflowers sown in May or June into rows 30cm (12in) apart, leaving 15cm (6in) between the plants. This will encourage the formation of a branching root system.

:: Choose the types of trees and shrubs you may like for future planting as you spot them on your travels. Place orders for autumn delivery.

:: Sow larkspur and 10-week stock for extra colour under glass in winter.

:: Take leaf cuttings of African violets.

:: Pinch off faded rose flowers to encourage more flowers later.

:: Water pots and hanging baskets daily.