Tamsin Westhorpe is the editor of 'The English Garden' magazine, theenglishgarden.co.uk
Anna Eavis is English Heritage's curatorial director, english-heritage.org.uk
Ben Cowell is the National Trust's deputy director of external affairs, nationaltrust.org.uk
East and Midlands:
Wollerton Old Hall
"A four-acre garden for plant enthusiasts, with distinctive garden rooms," says Tamsin. "Set around a 16th-century Hall House, the garden offers a modern twist on English garden style with an influence from the Arts and Craft movement of the 1800s, along with distinctive use of yews clipped into pyramids."
Wollerton Old Hall Garden, Wollerton, Market Drayton TF9 3NA (01630 685760; wollertonoldhallgarden.com)
"Pettifers is a garden lovingly created over the last 28 years by owner Gina Price," says Tamsin. "The one-and-a-half-acre, north-facing site enjoys views of the Oxfordshire countryside. A garden for all seasons with exceptional plant combinations."
Pettifers, Lower Wardington, nr Banbury, Oxfordshire. Open by appointment (01295 750232; pettifers.com)
"With peeling paintwork and overgrown courtyards, Calke Abbey tells the story of the dramatic decline of a country-house estate," says Ben. "The 'unstately home' has been left to vividly portray a period when many country houses did not survive – and in what remains, hidden treasures and fragile habitats can be found."
Ticknall, Derbyshire DE73 7LE (nationaltrust.org.uk)
"One of the greatest of all Elizabethan houses, this magnificent hall is testament to the vision, wealth and connections of the formidable Bess of Hardwick," says Ben. "Spectacularly sited high on a ridge amongst the formal gardens, the house provides a fascinating story of Bess and her descendants through their creations and collections."
Doe Lea, Derbyshire S44 5QJ (01246 850430; nationaltrust.org.uk/hardwick)
"A magnificent country house, Ickworth is renowned for the impressive rotunda that showcases the priceless treasures in its collection," says Ben. "A Heritage Lottery Fund project has brought the rotunda basement back to life, restoring it to its 1910 condition. Visitors can now discover the real lives of those who lived and worked upstairs in this extraordinary house through real testimonies and stories."
Horringer, Suffolk IP29 5QE (01284 735270; nationaltrust.org.uk/ickworth)
"Set in the middle of a beautiful countryside estate, Attingham was designed to impress," says Ben. "Owned by the same family for 160 years, it tells a fascinating story of love, neglect, spending and saving as fortunes rose and fell. Visitors can follow in these footsteps and experience afternoon tea in the mansion or simply enjoy walks in the magnificent grounds."
Atcham, Shropshire SY4 4TP (nationaltrust.org.uk)
"A breathtakingly beautiful stately home built to entertain royalty," says Anna. "Audley End stands proud within its Capability Brown landscape and the restored service wing and stables, complete with horses, provide a unique insight into life below stairs."
Off London Road, Saffron Walden, Essex CB11 4JF (0870 333 0606; english-heritage.org.uk/audleyend)
"After decades behind virtually closed doors, its treasures overgrown and largely unknown, one of Britain's largest and most important 'secret gardens' has been restored," says Anna. Wrest Park has a French-style mansion, recently restored Italian and rose gardens and miles of reinstated historic pathways.
Silsoe, Luton, Bedfordshire MK45 4HR (01525 860000; english-heritage.org.uk/wrestpark)
The Forestry Commission's National Arboretum boasts more than 18,000 trees from all over the world, which can be viewed from 17 miles of marked trails. The informal Silk Wood is carpeted with bluebells in spring and wildflowers in summer before giving way to autumnal reds and burnished orange.
Westonbirt, Tetbury, Gloucestershire GL8 8QS (01666 880220; forestry.gov.uk)
At the age of 30, the future Lord Fairhaven decided to restore a run-down house and patch of land into a fabulous Jacobean-style home. He entertained guests throughout the 1930s with luxurious shooting parties and the sights, scents and sounds of a beautiful garden and working watermill, all of which are open to visitors today.
Quy Road, Lode, Cambridge CB25 9EJ (01223 810080; nationaltrust.org.uk/anglesey-abbey)
"Famous at the site of that scene where Mr Darcy emerges from the lake in ~the TV adaptation of Pride and Prejudice, Lyme Park is also a spectacular Edwardian house found amid wild moorland," says Ben. "Visitors can travel back 100 years to discover the golden age of Lyme, with interactive activities tracing Edwardian life."
Disley, Cheshire SK12 2NR (01663 762023; nationaltrust.org.uk/lyme-park)
"The impressive gardens and Victorian country house, built in an Elizabethan style, have been in the same family since the 15th century," says Tamsin. "Home to the oldest herbaceous borders in the country, Arley Hall has eight acres of formal gardens and a further six acres of woodland walks. Don't miss the incredible Quercus ilex columns."
Arley Hall & Gardens, Northwich, Cheshire CW9 6NA (01565 777353; arleyhallandgardens.com)
"Enter the world of Lord Armstrong – Victorian inventor, innovator and landscape genius," says Ben. "Cragside was a wonder of its age – the first house in the world to be lit by hydro-electricity and crammed full of ingenious gadgets. The grounds are just as wonderful; one of the largest rock gardens in Europe leads down to the Iron Bridge, with superb views across the surroundings."
Rothbury, Morpeth NE65 7PX (01669 620333; nationaltrust.org.uk/cragside)
Parts of Haddon Hall in Bakewell, Derbyshire, date back to the 12th century, and when the 9th Duchess of Rutland arrived here in the early 20th century she overhauled the gardens into their current romantic splendour – it's only a shame just two of the rose terraces are open. Three versions of Jane Eyre, as well as Elizabeth, Pride & Prejudice and The Other Boleyn Girl have used Haddon as a location.
Bakewell, Derbyshire DE45 1LA (01629 812855; haddonhall.co.uk)
"An 18th century dolls' house, fine Chippendale furniture and the Brueghel masterpiece The Procession to Calvary are just some of the treasures to be found inside this fascinating country house," says Ben. "You can also explore more than 300 acres of garden and parkland, find a place to picnic and enjoy the newly planted orchard and adventure playground."
Nostell, West Yorkshire WF4 1QE (01924 863892; nationaltrust.org.uk/nostell-priory)
Scampston Walled Garden
"Highly praised for the perennial meadow garden, created by acclaimed plantsman Piet Oudolf," says Tamsin. "This modern planting style offers a great contrast to the traditional gardens. Enjoy the mile-long Cascade Circuit Walk around the gardens and lakeside."
Scampston Hall, Malton, North Yorkshire YO17 8NG (01944 759111; scampston.co.uk)
Herterton House Gardens
"Up until 36 years ago the garden was a derelict farmstead," says Tamsin. "Today it is an exceptional plantsman's garden. The garden was partly inspired by the paintings by Klee and Mondrian, and features a physic garden packed with medicinal plants."
Herterton House Gardens, Hartington, Cambo, Morpeth NE61 4BN (01670 774278; britainsfinest.co.uk)
Belsay Hall, Castle and Gardens
Belsay offers a great-value family day out and is one of Northumberland's most visited attractions. "The walk from the Greek-inspired house through exotic quarry gardens to a medieval castle is a truly magical experience," says Anna.
Belsay, Nr Morpeth, Northumberland NE20 0DX (01661 881 636; english-heritage.org.uk/belsay)
Brodsworth Hall and Gardens
Almost everything at the Hall has been left exactly as it was when Brodsworth was still a family home," explains Anna, "and the beautiful grounds have been restored to their full Victorian splendour."
The grounds feature a collection of grand gardens in miniature and there is a new children's play area.
Brodsworth, Doncaster, South Yorks DN5 7XJ (english-heritage.org.uk/brodsworth)
The Royal Horticultural Society's gardens at Harlow Carr were laid out around springs of sulphur water, which people have been bathing in since the early 18th century. The informal gardens include an enchanting wildflower meadow, lawns, flower beds and have something for every season.
Cragg Lane, Harrogate, North Yorks HG3 1QB (01423 565418; rhs.org.uk)
Chatsworth is as famous for the people who have lived there as its fabulous house and extensive gardens. The Dowager Duchess of Devonshire, Deborah, one of the Mitford sisters, was instrumental in returning the house to its former glory over the past 50 years, and a current exhibition (until December) celebrates Chatsworth's many infamous house guests.
Bakewell, Derbyshire DE45 1PP (01246 582204; chatsworth.org)
Gresgarth Hall Gardens
Lady Arabella Lennox Boyd has been designing gardens for four decades but at Gresgarth you can visit her own, a 12-acre collection of trees, shrubs and plenty of colour 30 years in the making, pervaded throughout by the gentle sound of water. The gothic mansion house is also open.
Caton, Lancaster, Lancashire LA2 9NB (01524 771838; arabellalennoxboyd.com/gresgarth)
Fountains Abbey and Studley Royal Water Garden
Two for the price of one with this abbey and elegant Georgian water garden. Next to the ruins of the 12th-century abbey is the only surviving Cistercian corn mill and there are neo-classical statues, follies and wonderful views.
Fountains, Ripon HG4 3DY (01765 608888 nationaltrust.org.uk/fountains-abbey)
Wales and Northern Ireland:
"One of the finest 17th-century Restoration houses, Tredegar has recently come under the stewardship of the National Trust and tells the stories of the flamboyant Morgan family," says Ben. "Visitors can play parlour games and figure out what those gadgets were used for in a 19th-century kitchen. It is surrounded by 90 acres of parkland including the great lake, three walled gardens and an orangery."
Newport NP10 8YW (01633 815880; nationaltrust.org.uk/tredegar-house)
"A place of distinct styles and contrasts, this eccentric 18th-century country house sits boldly on a rolling hillside overlooking Strangford Lough, oozing personality," says Ben. "Two very different styles of façade – one classical, the other gothic – provide an intriguing distinction, while history meets recreation across the 820-acre estate, home to a working mill and tower-house, plus miles of woodland and lough-shore trails."
Strangford, Co. Down BT30 7LS (028 4488 1204; nationaltrust.org.uk/castle-ward)
"A unique hotel resort that offers sea views, theatrical buildings and formal gardens with a Mediterranean feel," says Ben. "Woodland walks are spectacular in spring. Architect Clough Williams-Ellis bought the site in 1925 and is responsible for the look it enjoys today. Famed for its pottery and for being featured in the classic TV series The Prisoner."
Portmeirion, Gwynedd, LL48 6ER (01766 770000; portmeirion-village.com)
"This garden is one of the most beautiful in Britain and full of plants from all over the world," says Anna. The slopes of Bodnant have views across to Snowdonia and the upper part, around Bodnant Hall, is a stunning construction of terraces and lawns.
Tal-y-Cafn, nr Colwyn Bay, Conwy LL28 5RE (01492 650460; bodnantgarden.co.uk)
"Created in the mid 1860s by the Reverend John Moore, this informal plantsman's garden reflects the beautiful natural landscape of the surrounding area," says Anna. The displays include spectacular shrubs, wildflower meadows and a natural rock-garden wood.
Saintfield BT24 7LH (028 97510131; nationaltrust.org.uk/rowallane-garden)
"Mount Stewart has a neo-classical house and celebrated gardens and tours of the opulent building reveal its fascinating heritage and historic world-famous artefacts and artwork," says Anna. Much of the garden was designed by Edith, Lady Londonderry, and there is a strong Mediterranean feel with the view resembling an Italian landscape.
Portaferry Road, Newtownards BT22 2AD (028 4278 8387; nationaltrust.org.uk/ mount-stewart)
Dewstow is an Aladdin's cave of tunnels and underground grottos only rediscovered in 2000. The gardens were built in 1895 and buried in the late 1940s and, alongside the sunken labyrinths, you'll find charming ponds and rock gardens.
Dewstow Gardens, Caerwent, Monmouthshire NP26 5AH (01291 431020; dewstowgardens.co.uk)
This villa from the 1790s is from architect John Nash and the most complete example of his early work. The estate remains a working farm with rare breed cattle, sheep and pigs and visitors can see the dairy, laundry, brewery, salting house and walled kitchen gardens, where the produce is for sale.
Ciliau Aeron, nr Aberaeron SA48 8DG (01545 570200; nationaltrust.org.uk/llanerchaeron)
Great Dixter House and Gardens
"A place of pilgrimage for fans of the late plantsman, Christopher Lloyd," says Tamsin. "The garden is still boldly planted with his trademark bright-colour combinations. Visit the house, which is one of the largest surviving timber-framed halls in the country, to take a step back in time – Llyods's writing desk being the highlight."
Great Dixter, Northaim, Rye, East Sussex TN31 6PH (01797 252878; greatdixter.co.uk)
Tresco Abbey Gardens
"Enjoying a mild climate and all the charms of an island setting, this garden is unique and an explorer's paradise," says Tamsin. "The two-and-a-half-mile-long island (one of the Isles of Scilly) is home to many sub-tropical plants. No cars and lots of plant-filled peace and quiet – a must-see-before-you-die garden."
Tresco (01720 422849; tresco.co.uk)
"Originally designed as a tourist attraction, Stowe remains a spectacular place to explore," says Ben. "Newly restored, the Georgian Coaching Inn is the gateway to a spectacular garden filled with temples, monuments and an inspiring backdrop of lakes and valleys."
Buckingham, Buckinghamshire MK18 5EQ (01280 822850; nationaltrust.org.uk/stowe)
"Atmospheric Stuart mansion on the banks of the river in leafy Richmond-upon-Thames," says Ben. "Housing a superb collection of textiles, furniture and art, it is also reputed to be one of the most haunted houses in Britain."
Richmond-upon-Thames, Surrey TW10 7RS (020 8940 1950; nationaltrust.org.uk/hamhouse)
"Nuffield Place is the charming former home of the founder of Morris Motor Cars – and one of Britain's greatest philanthropists – Lord Nuffield," says Ben. "Following a recent fundraising campaign to save it for the nation, it opened in April this year and has a time-capsule quality with many of Lord Nuffield's personal mementoes, including his unique tool cupboard in the bedroom."
Huntercombe, Oxfordshire RG9 5RY (nationaltrust.org.uk)
"The much-loved home and place of inspiration for Winston Churchill, Chartwell resonates with echoes of the great man," says Ben. "The rooms remain much as they were when he lived here, while the hillside gardens reflect his love of landscape and nature. This year, a new exhibition reveals some of Churchill's personal items for the very first time."
Westerham, Kent TN16 1PS (01732 868381; nationaltrust.org.uk/chartwell)
"At Eltham you have the extraordinary experience of seeing a 1930s Art Deco mansion right next to the medieval Great Hall of Richard II's Eltham Palace," says Anna. The wealthy Courtauld family built the 20th-century house with its stunning entrance hall and impressive panelled dining room.
Court Yard, Eltham, Greenwich, London SE9 5QE (020 8294 2548; english-heritage.org.uk/eltham)
Osborne House, with its views across the Solent, has been causing quite a splash recently because of its newly opened beach.
"Visit Queen Victoria and Prince Albert's family home in the Isle of Wight and the private beach where Victoria used to swim," says Anna.
York Avenue, East Cowes, Isle of Wight PO32 6JX (01983 200022; english-heritage.org.uk/osborne)
Knoll Gardens and Nursery
Knoll is a large nursery with an impressive show garden with 10 Chelsea Gold medals. The four-acre garden displays Knoll's speciality, ornamental grasses and a collection of international rare and unusual trees and shrubs. Autumn is the peak season to see the grasses and deciduous woody plants.
Hampreston, Ferndown, Dorset BH21 7ND (01202 873931; knollgardens.co.uk)
Most of Dartington Hall's garden, which is less well known than it should be, was created in the 20th century. New York society landscape gardener Beatrix Farrand, Edith Wharton's niece, designed much of the garden, including the courtyard and woodland glades, and there are also magnificent trees and borders and a Japanese garden.
Dartington, Totnes, Devon TQ9 6EL (01803 86267; dartington.org)
Royal Botanic Gardens, Kew
A world heritage site in 121 hectares between Richmond and Kew, south of the River Thames. Kew was once a royal residence and its history spans 250 years. As well as fine specimens of trees and plants from around the world, the six glasshouses contain the best selection of exotic plants you will find in the UK.
Kew Gardens, Richmond, Surrey TW9 3AB 9020 8332 5655; kewgardens.org)
Owned by the Duke of Northumberland and home to his family for more than four centuries, Syon Park is just 10 miles from central London. The impressive house with its Greco-Roman Great Hall, a splendour of marble, is open to the public, and Capability Brown landscaped the park and gardens in the mid-18th century.
Richmond upon Thames, Middlesex TW8 8JF (020 8560 0881; syonpark.co.uk)
Sissinghurst Castle and Gardens
The writer Vita Sackville-West and her diplomat husband Harold Nicolson led the revival of Sissinghurst in the 1930s and it remains a thrilling encounter, today under the stewardship of Sarah Raven, the garden and food writer who lives in the National Trust property with her family.
Sissinghurst, Cranbrook, Kent TN17 2AB; 01580 710700; nationaltrust.org.uk/sissinghurst-castle)
"At Broadwoodside you can discover a major new garden that was started in 2000," says Tamsin. "The spectacular buildings work with the modern design and it is a great example of old and new working together. The aviary in the Upper Courtyard, should not be missed."
Broadwoodside, Gifford, East Lothian, Scotland (broadwoodside.co.uk)
Logan Botanic Garden
"Logan is Scotland's most exotic garden," explains Anna. "It is warmed by the Gulf Stream, which allows southern-hemisphere plants to flourish in this patch of paradise near Port Logan in Dumfries & Galloway."
Port Logan, Nr Stranraer, Dumfries & Galloway DG9 9ND (01776860231; rbge.org.uk/the-gardens/logan)
"Although Cambo House is a hotel, the 19th-century mansion has grounds that are open to the public, including the largest walled garden in Scotland," says Anna. "The traditional Victorian garden with a burn running towards the sea is updated with naturalistic plantings. Visit as spring breaks for the marvellous snowdrop blanket across 70 acres of woodland."
Kingsbarns, St Andrews, Fife KY16 8QD (01333 450 054; camboestate.com)
Colonsay House Garden
Colonsay is remote but it has one of the country's best rhododendron gardens, with many varieties. It was planted mostly in the 1930s and along with 20 acres of woodland garden are formal walled gardens with climbing roses and clematis.
Isle of Colonsay, Argyll PA21 7YU (01951 200211; colonsay.org.uk)
Arran is one of Scotland's more accessible isles and stunningly beautiful. Brodick Castle can be traced all the way back to the Vikings and its setting is as striking as its proud turrets – it looks out over the sea and sits in the shadow of the mountain of Goatfell.
Isle of Arran, North Ayrshire KA27 8HY (01770 320303; nts.org.uk/Property/Brodick-Castle-Garden-Country-Park)
Cawdor Castle dates back to the 14th century and remains a family home. Built as a fortress, it is forbidding but also enjoys a magical Harry Potter aspect. There are three gardens – walled, flower and wild, and a burn, and the unusual microclimate allows for a surprisingly lush and fertile grounds given that Cawdor sits north of Moscow.
Nairn, Highland IV12 5RD (01667 404401; cawdorcastle.com)
Best for... Art lovers
The impressive rotunda at Ickworth contains a stunning collection of the Harvey family's silver. The surrounding woods and gardens are worth exploring, too
Best for... Sci-fi fans
This famous resort was featured in the Prisoner but it is known today for its woodland walks, sea views, formal gardens and collections of pottery
Best for... Flower lovers
This garden is the work of the late Christopher Lloyd and boasts his trademark bright colour combinations. The timber-framed Tudor hall is worth a visit too