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You are here: Home / History / The Tanked Bed created by Anthony Parsons for Royal ferns

The Tanked Bed created by Anthony Parsons for Royal ferns

10th March 2023 By Colin Adlam Leave a Comment

Osumnda regalis
Gymnocarpium dryopteris or Oak fern
Osumnda regalis Purpurascens
Anthony Parsons' Tanked bed at The Danesbury Fernery, Hertfordshire

A Problem for Parsons

Although expert as a fern cultivator, Anthony Parsons had his frustrations developing the Danesbury Fernery. In particular, he could not get one family of native ferns ‘the Royals’ to grow to their best advantage. He grew these large ferns “at a fair distance apart” and was not going to rest easy unless “they became handsome and noble specimens”.

So, he developed the idea of planting them in a ‘tank’ within a specially constructed, irregularly shaped, bed that was well-drained. Parson wrote extensively about his ultimate success.

He described in mid 1860s publications how he constructed the bed, and how he filled it with his favourite mixes of soils and manures.

“a piece of ground, of irregular shape, large enough to contain about 20 plants, was staked out, and the mould, or, more correctly speaking, the chalk, was removed to the depth of 3 ft. ; a bricklayer followed, and put in a floor of three bricks laid on the flat, set in good Portland cement, and over that a layer of plain tiles, the sides being made up to the ground-level with a 4″-inch wall, well built up in the same kind of cement ; this made the whole water-tight, and prevented the roots of the surrounding trees from penetrating and robbing the ferns of their moisture”.

Parsons’ original ‘Irregularly shaped’ tanked bed excavated.

About 160 years later we have now excavated Parsons’ zig-zag bed, (so-called because of its shape). By following Parson’s own techniques we hope to be able to grow and display the ‘Royals’ as successfully as he himself did in the late 19th Century.

The bed is in superb condition, complete with a base of tiles on top of bricks, and with the pipework leading to a drain – “provision was made for the escape of the surplus water, by introducing into the front wall, at about 4 ins. from the bottom, a common 3-in. drainpipe, which communicated with a small tank, about 3 ft. square, sunk into the chalk, so that all wastewater became absorbed” .

Can we grow specimen ferns to match Anthony Parsons’ ambitions?

Without doubt, Parsons and his gardening team put in a great deal of costly time and effort making sure that the ferns had the best possible loam, peat and leaf-mould to feed on.

“The space was filled up with earth, compounded of good loam, peat, and leaf-mould, in equal proportions, with about one-fifth of good rotten manure added thereto; these ingredients were thoroughly mixed and well-trodden in, and then the ferns were planted. In forming this bed”.

Parsons claimed that “the plants (were) far surpassing in size any I have ever seen under artificial cultivation, and, judging from reports, rivalling their growth in their natural habitats. Last season I could boast of Osmunda regalis with fronds at least 8 ft. in length, Osmunda spectabilis 4 and 1/2 ft., Osmunda Claytoniana 5 ft., Osmunda cinnamomea 3 ft., and the beautiful Osmunda regalis, var. cristata, 3 ft. in length. Adiantum pedatum grew from 2 ft. to 3 ft. in height, and others were proportionally fine“.

Parsons described in print how every spring – “I apply a dressing of about two inches of rotten manure to the surface, and just cover it with mould for the sake of appearance“.

Well today’s volunteers can try to match that, and we certainly have plenty of leaf-mould on site to help.

Conclusion

Parsons was unashamedly proud of his work with his Royal ferns – “The artificial swamp is the admiration of all the visitors here. The plants are always in a healthy and vigorous state, and have none of that half-starved appearance so frequently to be seen. The result of my experience induces me to believe that a more liberal treatment would not be found objectionable in the cultivation of many more of our native ferns. I intend making the experiment this season, and may possibly find time to make known what amount of success I may meet with”.

Colin, our very own fern expert, has taken note.

Since Parsons’ zig-zag bed was re-discovered during excavation work in 2019 it has been emptied of the old dry ‘mould’, or soil, that remained and re-filled with mixed soil and composted bark. We water regularly in summertime and top up with compost each year.

With Parsons in mind, today’s zig-zag bed has been planted up with Osmunda regalis, Osmunda regalis ‘Purpurascens‘, Polystichums, Adiantum, Holly fern (Cyrtomium falcatum)and the tiny Gymnocarpium dryopteris or Oak fern. Most of these ferns are doing very well in the conditions.

We believe that most of the herbaceous beds in the Fernery were eventually tanked by Parsons, and we have found plenty of evidence of that.

But one final piece of the jigsaw still needs investigating: Parsons mentioned – ‘a soakaway’ 3 feet square’, but the zig-zag’s own soak-away is significantly smaller than that. Perhaps Parsons was referring to the huge ‘sump’ that we have excavated in front of the grotto, which would act as a soak-away for the entire site?

More of that another time.

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Copyright © 2025 Friends of Danesbury Fernery (FODF). Non attributed photography by John Roper.