What You Need to Know About the Thuja Green Giant

What You Need to Know About the Thuja Green Giant

The background

The thuja Green Giant is actually a cross between two other thuja varieties, the Standishii and the Plicata. It was introduced to the United States National Arboretum by DT Poulsen of Denmark back in 1967.

The Standishii is a native of Japan and the Plicata is native to the US. The former reaches heights of 20-35 feet and the Plicata can achieve up to 70 feet; the hybrid, the Green Giant, generally reaches between 30 and 40 feet. It also has an attractive conical shape, as well as interesting colours and strong resistance to pests and disease.

What You Need to Know About the Thuja Green Giant

What you need to know

The Green Giant thrives in USDA zones 5-9, meaning it’s very hardy. It can do well down to minus 20C and handles the weight of snow on its branches nicely. Used as a barrier, the dense foliage will stop snow blowing onto your paths and drives, as well as creating a windbreak to protect smaller, softer trees and plants.

The barrier effect from the green giant also helps to keep homes warm, as they stop so much wind getting inside. They can also shade a house well, too, reducing the costs of air conditioning in the summers.

Fast growers

These trees grow between three and five feet a year, so if you’re looking for a privacy screen, you can’t do much better! They also respond well to pruning, which you’ll need to do if you’re maintaining a dense hedge. They can grow to 12-20 feet wide at the base, so plan your hedge carefully. If you buy your thuja Green Giant trees from The Tree Center or another online supplier, you can get plenty of planting advice there.

Good lookers

While many people see this tree as purely functional, many others appreciate its beauty. It has a striking conical shape as well as light green feathery foliage on the outside. The inner foliage tends to be darker, with hints of yellow, so they work well both on their own and as a backdrop to flowering trees and bushes.


Thuja Green Giants are very easy to look after; just make sure they have partial to full sunlight – six hours a day is enough. They also adapt well to lots of different soils; they prefer mildly acidic, but get on well with almost all other types.


It’s important not to let the trees get soggy, though, so make sure they’re not planted anywhere where water drains or stands. They need watering once or twice a week for the first six months, then just occasionally if there’s a prolonged drought. They benefit from a good thick layer of mulch, as this keeps the soil moist and helps to regulate the temperatures around the roots and base. You don’t really need to add fertilizer unless your whole garden needs it regularly. If you do decide to fertilize, do it after the final frost or at the start of fall.


If the needletips turn brown or yellow the tree is thirsty and if the branches start to sag and discolor the tree may be over-watered. Couldn’t be easier, really!

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