Birr Castle's oldest tree, the Carroll Oak, was planted before the Parsons family arrived in 1620, and probably around 1550. It stands in the open parkland of the demesne. Near the castle, on the lower terrace of the Formal Gardens, are box hedges the castle calls the tallest in the world, somewhere between nine and twelve metres depending on who measured. A dawn redwood grown from 1940s seed completes the three. All of them are inside the ticketed demesne, open all year.
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Pedunculate OakNo photograph yet Pedunculate Oak · 400 years
The oldest tree at Birr Castle carries the name of the family that lost the place. The O'Carroll clan held Birr until the 1620s, and the estate says this oak was certainly planted before the Parsons family arrived in 1620. Who put it in the ground, the estate does not say.
In 2005 the Irish Times reckoned it had been planted about 455 years earlier, around 1550, and that it was set to last roughly as long again. The national heritage tree register gave it 300 to 500 years in 2009. Taken together, the honest answer is more than four centuries, possibly closer to five. Nobody has counted its rings, so the range stays a range.
The register records it as a maiden oak, meaning a single trunk that was never cut back for timber, and notes the evidence of significant wildlife habitat in it. In 2005 a carefully trimmed circle was kept clear around its base. Of all the trees on these 120 acres, it is the one the estate names as its oldest, the only one it places before the Parsons.
No girth or height for it has been published. If you have measured it, tell us.
Birr Castle Demesne is ticketed and open all year, with about ten kilometres of paths. Dogs are welcome on leads. The castle itself is a private home.
Common BoxNo photograph yet Common Box · 200 years
Birr Castle says these are the tallest box hedges in the world, and Wikipedia says Guinness agrees. What nobody agrees on is how tall that is.
The castle itself gives no figure. Travel writers have filled the gap freely. One guide says 12 metres, another about 40 feet, the Irish Times 31 feet, another 32. That puts them somewhere between nine and twelve metres, which for a plant most people know as a knee-high border is absurd enough without settling the decimal.
The age is just as loose. One guide says they were planted in the 1780s. Wikipedia says more than 300 years. The national heritage tree register, which lists an avenue of multi-stemmed box at Birr, gave 200 to 300 years in 2009. So these hedges are at least two centuries old, perhaps more, and any single date you read is one source's guess.
What they are is easier to say. Two walls of clipped box face each other on the lower terrace of the Formal Gardens and make a green corridor several times your own height. Box is a slow grower, so the height alone tells you how long these walls have been kept.
The Formal Gardens are inside the ticketed demesne, open all year. The castle is a private home and not part of the visit.
Dawn RedwoodNo photograph yet Dawn Redwood · 80 years
Until the 1940s, science knew the dawn redwood mainly as a fossil. Living trees were found and described in China between 1941 and 1948, and seed travelled west soon after. Birr Castle says some of that first seed reached its gardens in the 1940s, and that a fine tree from that period still stands.
That makes this one of the youngest trees on our Irish map and, in a sense, one of the oldest. Its line runs back through the fossil record. Its own trunk runs back about eighty years, to seed that reached Birr while the species was still news.
The national heritage tree register lists a dawn redwood at Birr as an exceptional specimen, aged 50 to 100 in 2009, and it is the tree pinned here. The estate's page does not locate its 1940s tree or measure it, so the match between the two rests on species and age, not on anyone saying so outright.
It is a conifer that behaves like a broadleaf. The needles come out bright green in spring and turn a foxy reddish brown in autumn, then drop, leaving a tall, fluted trunk bare all winter. No girth or height has been published. If you know either, tell us.
The demesne is ticketed and open all year, with seasonal hours.