Forest giant

AT RHS Garden Harlow Carr, there’s one tree that stands out for me; frankly, you’d struggle to miss it. That is because it belongs to one of the world’s largest tree species called the sequoiadendron giganteum – also known as the giant sequoia, wellingtonia and sierra redwood.

Although our redwood still has a long way to go to achieve its full potential, it is still quite a remarkable tree. The sequoia belongs to the cupressaceae family (cypress family) and is the sole living species in the genus sequoiadendron. It is a very large evergreen conifer, conical in shape when young and with a mass of branches at the base. In older trees, the trunk is branch free with an irregular shaped crown. It has a distinctive reddish thick bark, which has a soft quality to it.

Naturally, it is only found in groves on the western slopes of the Sierra Nevada, whose parks include Yosemite and Kings Canyon in California. The sequoia rarely breeds in its original habitat due to the seeds requiring full sun and mineral soil, and this is why fire is essential to help the sequoia to breed.

These fires occur in the hot summers and lighting strikes and burn out rival saplings. Pines and firs only have a thin bark and a flameproof resin, whereas the sequoia has a flameproof tannin in its veins and bark that can reach 90cm thick, enabling it to withstand the full heat of the fire. As the fire diminishes the shade-loving species, the sequoia seeds are able to gain full sun, and the ash left over from the fires provides a perfect bed for them. The hot, rising air causes the cones to open and release the seeds so that they can fall down to the ground to germinate.

Probably the most famous sequoia is known as General Sherman, named by naturalist James Wolverton who served as a lieutenant under William Tecumsheh Sherman in 1931. It stands at an impressive 83m (275ft), with a trunk diameter of 36m (102ft) and is thought to be around 3,266 years old.

Many of the old giants were felled in the 19th and 20th Centuries. The wood itself decays very slowly and being fibrous and brittle, is unsuitable for construction. As the trees often shattered when they fell, foresters tried digging trenches and filling them with branches to cushion the fall, but despite their best efforts, still only around 50 per cent made it the mill. Others were simply too big to transport. There are around 75 groves left in the national parks and preserves in California at just over 144 square kilometres.

Here at Harlow Carr, we also have a sequoiadendron giganteum ‘Glauca’ which has a blue hint in its needles. It can only truly be appreciated during the winter months when it holds the snow very beautifully with its prefect conical (cone) shape. It’s another of my favourite trees in the garden.

I hope I have inspired you to come and visit our arboretum and take a look at our very own little giants.

Jobs for the week

Cut back deciduous ornamental grasses

Cut back side shoots of wisteria to two to three buds

Put up nest boxes for birds ready for the nesting season

Prune shrubs just as fuchsia, santolina and lavatera

DIARY DATES

February 13 to 21: February Half-Term Fun – The Secret Life of Insects

Delve into the secret world of insects at RHS Garden Harlow Carr this half term. Whatever the weather, there will be indoor craft activities and an outdoor trail to suit all ages. Activities vary daily and include: make a willow insect, become an Insect Inspector for the day, settle in for a bug-themed storytelling session, and plant seeds to encourage creepy-crawlies into your garden. There’s also a chance to have your face painted and to visit our insect laboratory – and win some special prizes, too. Normal garden admission

March 5 to 6: Mother's Day Weekend

Celebrate Mother's Day with a walk around RHS garden Harlow Carr – and perhaps a coffee and cake at Bettys Café Tea Rooms. Enjoy spectacular spring bulb displays – from daffodils and hyacinths to scillas and trilliums – and enter our photo competition for the chance to win a fabulous hamper worth £50. Normal garden admission applies.