English Heritage (EH) didn't get the kind of PR it was hoping for when the heritage quango let BBC cameras cover the six-year recreation of an Elizabethan garden at Kenilworth Castle, Warwickshire.

While the documentary, titled simply English Heritage, focused on the project's personal conflicts and logistical setbacks, it also contained the charge from one critic that there was "little evidence" on which to base the £2.1m reconstruction - a charge vehemently denied by EH head of gardens and landscape John Watkins.

"Every area of the garden can be referenced," he says. "We have had the benefit of a large range of experts, both inside and outside EH, such as architectural historian David Robinson, garden archaeologist Brian Dix, and garden historian David Jacques."

The symmetrical gardens were laid out in 1575 by Robert Dudley, Earl of Leicester, who was a favourite of Queen Elizabeth, to host 19 days of "princely pleasures" laid on for her at the castle.

Watkins says: "The main focus has been the research, during which we have developed a broad understanding of Elizabethan gardens as well as answering the specific questions like what else Leicester did."

The project would have been impossible without the existence of the so-called Langham Letter, which described the garden at its prime.

"Robert Langham was a cloth merchant, one of Leicester's court, who happened to be at Kenilworth during the 19 days of Elizabeth's visit," says Watkins.

"He wrote up his impressions in extreme detail, basically in order to boast to a friend. Fortunately, he had a measurer's eye, so was able to give the size of things like the obelisks as 15 feet, as well as the dimensions of the aviary."

In the absence of any foundations needed to support such massive stone structures, it was concluded that the obelisks must have been wooden, painted to look like porphyry, a brownish-red crystalline stone.

"We know that other buildings of the time were made of oak and painted to look like a variety of substances," Watkins adds.

Archaeological research did however corroborate other elements described by Langham. Excavations turned up part of the eight-sided base of the central fountain, as described in the letter, as well as lead piping leading to it, and three chips of the original white Carrara marble of which it was made.

"The archaeology ties in with the letter, and validates it," says Watkins. "It's better than having a plan of the garden. We know what actually went in."

The fountain has panels with sensual scenes from Ovid's Metamorphoses, based on contemporary images from other sources, and two life-size figures bearing a globe from which jets shoot water into a pool below. However, it was decided that actual fish would possibly meet a swift demise at the hands of visiting children, so have not been included.

Langham also describes a terrace atop a grassy bank on the castle side, with arbours at either end. These have been recreated from a broadly contemporary French engraving and have been planted up with musk roses, honeysuckle and vines.

An extra challenge came in the form of 21st-century health and safety regulations, which required the arbours to be tested for wind load. As a result, the original wooden structures had to be taken down and strengthened with steel rods, at considerable extra expense.

Considerations of accessibility also led to the installation of a stairlift at the end of the bank. And where excavations revealed perimeter walls, beech hedges have been planted instead to reduce costs.

Planting

Frustratingly for the team, Langham had identified few of the plants. Instead, a wide range of historical sources were used to build an impression of the garden's likely planting scheme. These included a contemporary painting from the royal collection, which showed Maltese cross (Lychnis chalcedonica) in use, along with wallflowers, stocks and irises.

Watkins says: "We know there were fruit trees and strawberries, that there were many of what were called 'herbs' and that it was heavily scented. We are having to learn to garden as Elizabethan gardeners and designers, to get into their minds. We have faced the same challenges and, as much as possible, we have used traditional methods and materials."

It was described in the letter as a 'gillylower garden'. Also called clove pinks (Dianthus caryophyllus), gillyflowers had been introduced in the 1540s from the Mediterranean. The Royal Botanic Garden Edinburgh has provided some specimens from the Atlas Mountains in Morocco.

"They would have been the height of fashion," says Watkins. "Twenty years later it would have been completely different. This was the last shout of a particularly English style of garden."

Generally the choice of plants available "has not been overly limiting", he says. "A German book dated 30 years after the garden told us that pretty much every hollyhock you can get today, you could get back then. You could also get all colours of aquilegias, and rose campion (Lychnis coronaria) in white, red, pink and rose."

As well as the purely ornamental, the garden is known to have contained fruit trees. "All the varieties would have been available then," says Watkins. The small-fruited, semi-wild mazzard cherry, for example, is known to have been a Roman introduction.

Many were sourced from Kent-based specialist fruit tree nursery Keepers Nursery. Nursery partner Hamid Habibi says that although the Victorians were avid documenters of fruit varieties, earlier generations were less assiduous. "The histories of a lot of varieties are known, but not 100 per cent," he says. "We know that 'Black Worcester' pears were around at the time because they feature on Worcester's coat of arms, and Elizabeth herself was presented with them when she visited the city."

In keeping with history

A mixed hedge of field rose, hawthorn and wild privet will also bring forth spring flowers and autumn fruit. Secateurs and trimmers would have been in use at the time, Watkins adds. "Yew wasn't used architecturally, and box was considered indecent-smelling," he points out.

Instead, contemporary sketches and tapestries suggest that herbaceous plants such as thrift, daisies and strawberries would have been used for edging.

"The sketches give us the spacing, the rhythm, the overall form of a typical garden of the era," says Watkins. "We need to forget the Edwardian style of soft, intermingling plants. This is much more about control - plants are kept in their place, and the beds would not have looked full."

To keep the bare earth weed-free, the un-Elizabethan expedient of mulch has been employed.

Garden supervisor Fiona Sanders was recruited last year to manage the site. "It's been a long project, with a very detailed planting plan," she says.

"We know that all the plants we've used were available at the time. We have documentary evidence that African marigolds (Tagetes erecta) had arrived by 1572. But some, such as heartsease (Viola tricolor) are difficult to source because they're not available commercially."

Sanders has worked at a raptor centre and the experience has given her more confidence in managing the aviary birds, she explains. Even the birds have been selected for authenticity. Watkins says: "Pheasants came from the Far East via the Silk Road and the Romans, while guinea fowl were reintroduced to Europe in the 1540s by the Portuguese."

A book bringing together all the different strands of research will be published next year, says Watkins, explaining that the site itself "is a 3D essay on the Elizabethan garden".

PLANT LIST

Entrance to garden

Mespilus germanica 'Large Dutch', Cydonia 'Portugal'.

Knot beds and borders

Alcea rosea, Amaranthus paniculatus, Aquilegia vulgaris, Armeria maritima, Artemisia abrotanum Award of Garden Merit (AGM), Bellis perennis, Calendula officinalis, Cheiranthus cheiri, Convallaria majalis AGM, Fragaria vesca 'Baron Solemacher', Dianthus barbatus, D. 'Caesars Mantle', D. carthusianorum, D. 'Clifford Pink', D. 'Cockenzie', D. 'Old Velvet', D. 'Pheasants Eye', D. plumarius, D. 'Priory Pink', D. 'Solomon', D. 'Ursula le Grove', D. 'White Ladies', Daphne mezereum, Delphinium consolida, Helleborus foetidus, Hesperis matronalis, Ilex aquifolium, Iris germanica, Juniperus communis AGM (standard and tiered), Lavandula augustifolia, Lilium candidum, Lychnis chalcedonica, L. coronaria AGM, Matthiola incana, Nigella sativa, Paeonia officinalis, P. mascula subsp. mascula, Primula elatior AGM, P. veris AGM, P. vulgaris, Rosa x alba 'Great Maiden's Blush', Rosmarinus officinalis, Salvia officinalis, Santolina chamaecyparissus AGM, Tagetes erecta, Viburnum tinus, Viola odorata, V. tricolor.

Arbours, terrace and quarters

Rosa alba 'Maxima', R. x damascena var. semperfloreus, R. x damascena versicolor, R. gallica var. officinalis AGM, R. gallica 'Versicolor' AGM, R. moschata and R. spinossissima.

Orchard and aviary area

Malus 'Coeur de Boeuf', M. 'Court Pendu Plat', M. domestica 'Decio', M. domestica 'Old Pearmain', P. 'Bullion Maiden', P. 'Greenstem Black Maiden', P. avium 'Hannaford', P. insititia 'Mirabelle de Nancy', P. avium 'Small Black', Pyrus 'Black Worcester'.

Boundary hedging

Crataegus monogyna, Ligustrum vulgare, Rosa arvensis, Rosa eglanteria.