How to Care for Thuja Green Giant in Spring

In the garden it makes sense to establish a season routine, so that plant care happens at the times when it can have the most impact. Thuja Green Giant, grown as a hedge or screen, or as a specimen tree, is low-maintenance and easy-care, but some basic activities can make the difference between good and great. So let’s see what should be done for it at this time, as your garden is waking up, and new growth is everywhere. These things are especially helpful for new plants, perhaps ones put in last year, or planted over the winter.


A good fertilizer program is the best way to get the maximum growth this plant is capable of. If you planted Thuja Green Giant, then you probably wanted something that would grow quickly, and create the hedge or screen you wanted, in the least possible time. You can help that out by using a suitable fertilizer for your situation.

Young plants benefit from liquid fertilizers. These carry the nutrients already dissolved in water, so they are immediately available for the roots to take up. They are especially useful for the limited root volume of new plants, and their rapid availability means a quick response from the plants. These fertilizers are available either as concentrated liquids or as powders. Whichever you use, follow the directions carefully, as too much can make for big problems, with browning foliage and even death a possibility. Used correctly they are safe and efficient. Once mixed with water at the right concentration, water onto the roots, making sure you cover the whole root zone, which is a couple of feet or more in each direction.

Liquid fertilizers can take a while to apply, especially on a long hedge, although hose-end applicators make it a lot easier and quicker. For more established hedges granular fertilizers, which are sprinkled onto the ground over the root zone, are much easier to use, and have the advantage of lasting much longer. While liquid fertilizers need re-applying every two weeks to a month, granular fertilizers need on only two or three applications a year. In fact, if you go for the modern slow-release forms, once a year, in spring, is all you need. These are more expensive, but the saving in time and remembering to re-apply is worth it. Fertilizer spikes are not so effective, as they do no give even coverage. They can be useful for a single plant, but overall their cost and reduced efficiency is hard to justify.

Increasingly, gardeners are choosing organic sources for fertilizer, to avoid using harsh chemicals. There is a also a greater understanding of the need to activate natural processes in the soil, which improve it, and increase nutrient flows to your plants. This is often achieved by boosting the levels of soil microbes, adding those that can be missing, or specific forms to tackle the fertilizer sources being used.

Whatever type of fertilizer method you use, make sure you choose something designed for evergreens. These always have a high first number in the formula printed on the box, something like 12-3-5. The exact numbers are not important, but the balance is. Look for a high first number, which is nitrogen, for green leaves, and ideally the last number – potash – will be a little more than the middle number, which is phosphorus. Potash makes plants more resistant to cold, heat and pests.


In many places spring is a time of rain, and extra watering is the last thing you think off, but in some areas a dry spring is always possible, so be ready to water if the soil dries. Because this is such an important time for growth, where much of the year’s growth can happen in a few weeks, any dryness is going to stop that.

If, in your area, you need to water your hedge very often, installing an irrigation line is a great time saver. The simplest and best is a leaky pipe, which weeps water from all over the surface. You need a pipe double the length of your hedge. Weave it in and out of the plants, laying it over the soil area, not right up against the trunks. Then use a regular hose to connect it to a tap. Let it run for several hours, so that the water soaks right in. An easy idea is to use a simple timer valve on the tap. This is then programmed for the length of time you need to run it, and you can also set it to run once or twice a week, if you don’t have substantial rainfall. If you have a built-in irrigation system you can connect it to that, as a zone.

Always check the soil moisture directly, by touching it, or using a moisture meter. Even after a lot of rain it can be dry around a hedge, because the dense foliage prevents the rain penetrating. This is especially true with heavy but brief thunderstorms.


A spring trim is always a good idea – for a hedge of any age. Start with an inspection and removing any dead stems or damaged branches. For new plantings it is important to trim lightly, even if the hedge hasn’t reached where you want it yet. This builds a dense structure, and it makes for a much better and longer-lived hedge. Just take the ends of the branches several times a year. You will hardly slow down the growth at all, but the result will be a terrific hedge. For established hedges, wait until the new growth has completely covered the hedge before trimming.

When you trim, pay close attention to keeping the front of the hedge sloping inwards a little. Never trim so that the top is wider than the bottom. This basic principle will give you a terrific long-lived hedge that always looks great.

For screening, trimming may not be necessary, but it still pays to go over the trees once a year, cutting back any branches that are outside the main structure, and even giving the whole screen a light trim. You may not want to reduce the size, but trimming will increase the density, and make for a more beautiful screen.


Attention to these basics will give you perfect Thuja Green Giant plants – however you are growing them. It simple, doesn’t take a lot of time, and pays you back in beauty and utility.