So you just planted that row of Thuja Green Giant? Congratulations, it’s the perfect choice for a a screen or hedge – but now you are wondering what to do next. So here is a check-list of things to do and watch for with your new planting, so that it grows as fast as possible – and that is fast – and soon looks like the image you had when you bought them.

Summer Care of Thuja Green Giant

  • Water regularly – soak deeply for several hours once or twice a week
  • Mulch – it controls weeds and conserves moisture
  • Feed it – liquid fertilizer is best for new plants
  • Trim lightly – don’t wait for it to reach full size before starting to trim
  • Relax – there isn’t much else to do with this easy-to-grow plant


The single biggest killer or growth-slower of new plants is lack of water. For the first season you need to keep watering close in to the stem of the plant, which is where the roots are. The biggest mistake with watering is to take the hose, with or without a spraying nozzle, and spend a few minutes spraying the ground. This water doesn’t penetrate very far at all, and the roots usually stay dry. Water needs to be applied slowly, so that it trickles down into the ground, and there are two ways to do that easily.

One easy way is to use an open hose, with the faucet turned down so it just trickles. Lay the hose a few inches from the stem and leave it for about half an hour. Check back and if the ground around the plant now looks thoroughly wet, move on to the next plant. If you do this once a week your plants should be really happy. At the height of summer, if there has been no rain and it is hot and windy, you may need to water twice a week – -check by scrapping back a bit of the soil to see if it is still damp or not.

The second method is a less work, so it’s a great choice if you have a longer hedge. Get a length of porous pipe and thread it back and forth around your plants, covering the ground with a sinuous line of pipe. You can use loops of coat-hanger wire bend over to anchor it in place and hold it down. It is best to do this before putting down mulch. This kind of pipe leaks all along its length, letting drops of water flow out onto the ground. How long it takes to soak the area depends on your soil, so you need to experiment, starting with an hour, and adjusting that time as needed. Adding a simple timer to the faucet makes it easy to do this automatically, even while on vacation, and once you set it up there is nothing more you need to do.


If you didn’t do it when planting, put down a 2 to 3-inch layer of coarse organic material over the root zone as mulch. This could be bark chips, shredded wood, shredded leaves, garden compost, or even straw. Not only does it reduce or prevent the growth of weeds, mulch keeps the soil cool, stimulating root growth, and it slows down the loss of water directly from the soil. Keep it clear of the stems and foliage and cover an area a couple of feet wide at least. You will probably need to renew it after a couple of years – it depends on the type of material you used. Once the plants grow and spread outwards the leaves that fall inside the plant will act as natural mulch, and you won’t need to do it anymore. Remember not to dig old mulch into the ground, as more woody kinds of materials rob the soil of nutrients as they rot down.


Your new Thuja Green Giant plants don’t yet have extensive root systems, so they can’t reach the nutrients in the surrounding soil. To keep them growing at their peak speed it is best to feed them for the first couple of years with liquid fertilizers, as these soak right down into the root ball, so the nutrients are available. The foliage can also absorb them directly, so some types can be sprayed directly onto the foliage. If you are unsure, use a half-strength mixture for the foliage, and full-strength on the roots. Once a month is usual, although you might get slightly better growth with half-strength every two weeks. Make the last feeding in mid-September, so the plants harden-off a little before winter comes. Choose a formulation that is blended for evergreen trees and that contains iron and other micro-nutrients. You will really see the difference with liquid feeding, no matter how well you have prepared the soil. That good soil preparation will pay off in future years, but it doesn’t have a big impact in the first season.


Although you want maximum growth, you also want to develop good structure in a hedge, so that it is durable and lasts for many years. So if you are planning a hedge you will clip regularly, start doing it the first season. Just take an inch off the top a couple of times through the season, and a little off the sides too, especially in the upper part, so that your plants slope inwards a little. Don’t be tempted to trim 90-degree sides. It doesn’t work well, as the lower branches will become thin over time, and you will lose that great lush greenness right to the ground that is the mark of a top-quality hedge. These light trimmings as the plants grow produce a dense structure that is resistant to storm damage, and won’t break under the weight of snow. Stop trimming in mid-fall, so that the growth slows naturally before the winter comes, to eliminate the risk of the tips burning if the weather turns cold suddenly.


These are all easy jobs, that don’t take long, but they pay off in spades, with top-speed growth, rich, healthy green foliage, and the best-looking plants around. Good care in the early years of Thuja Green Giant helps it become the great plant you want – it’s easy, so enjoy the summer.