A lot of the focus with caring for Thuja Green Giant is on the actual planting and establishment of new plants. This is important, because good establishment means durable plantings and a long life for your bushes. But after a few years your hedge, screen or specimen plants will be established in your garden, and questions come up about caring for these older plants. So in this blog we are going to focus on that – what special care and steps are best for older plants, particularly so that they go on to have a long, healthy life, and continue to play their vital role in your garden for years and decades to come.
It is obvious that newly-planted bushes need extra water until they settle in and send out their roots into the surrounding earth. But how long should this go on? What should we do for established plants if a long drought period arrives?
You should continue with watering new plantings throughout their first growing season. So if you planted in spring or early summer, it is best to water deeply once a week until the cold weather arrives, and winter rain or snow takes over. In the following year you should only need to water if there is a drought of three weeks, but if you have very sandy soil it pays to water regularly – perhaps every two weeks, for that second season. In later years you only need to think about watering if there has been no rain for a least a month, and in many soils your Thuja Green Giant plants will be unaffected by drought periods much longer than that.
The critical season for watering established plants is spring, not summer. Spring is when the major growth push takes place, and that is when the plants need plenty of water. So a spring drought can be damaging – although probably not fata – even to established plants. The new growth will be reduced, it will be thinner and not so green, and repeated over several years, the result will be a thinner plant. So if the weather turns dry in spring, as it so often can, a thorough soaking of your established plants will make sure they perform at their peak best.
Mulching also helps, and with hedges and screens leaving at least some of the clippings under the hedge is the easiest way to create a natural mulch for your plants. That layer of dead leaves will conserve moisture by reducing evaporation from the soil surface, as well as inhibiting weed growth. If you keep your hedge green right to the ground, then those clippings won’t show, and you save time by just blowing or brushing them underneath, instead of having to collect them up.
Young plants always perform best with a regular fertilizer program, but after a few years it can become less important. If your natural soil is a loam or clay soil, it will almost certainly have good natural levels of plant nutrients, and most plants will grow well in it without any assistance. If you have a sandier soil this is not true, and if that sounds like your soil situation, a fertilizer program should be kept up indefinitely. For established plants granular fertilizers, and slow-release fertilizer are best. These require fewer applications a year, and slow-release forms usually need just one spring application, saving you a lot of gardening time. Compare that to liquid fertilizers, which need applying every two to four weeks throughout the growing season – this can become a real chore, especially over the years.
It is usually best to keep up annual fertilizer application even if you have good soil, when growing a hedge of Thuja Green Giant. Trimming removes nutrients that would naturally be re-cycled within the plant, so these need to be replaced for optimum growth. This is also another good reason to spread your clippings underneath your hedge, rather than throwing them away, as their gradual decay will eventually return the nutrients in them to the roots. Evergreen clippings are generally not good in a compost heap, so leaving them in place is the best and easiest way to dispose of them.
In summary, keep fertilizing your evergreens indefinitely if you trim them more than once a year or more, and in all situations if your soil is sandy. For plants left to grow naturally, keeping up fertilizer application is less important on most soils.
If you have Thuja Green Giant, you probably decided when planting if you were going to trim them or not. Some people do underestimate the final size of this big plant, and trimming can become a necessity. If you suddenly see that your plants are too big, don’t rush out and cut them back hard. Like most evergreens, you cannot cut a branch back below where it has green shoots, and have it sprout back. If you get carried away and trim too hard you may destroy your hedge. If it really has become way too big, take back as much as you can, being sure to leave some green growth on every branch. After a year or so it will thicken up, and you can usually go back and get it even smaller than the first time. Better to take your time than destroy those old, established plants.
Even better is to anticipate a plant that is about to become too big, and trim it before, not after, that happens. It is much easier that way, and you will never have to trim so hard that your plants look bad for months, before filling out again.
With a hedge you should have trimmed regularly from an early age, but as your hedge matures it pays to anticipate problems. Keep those sides sloping inwards a little, so that the lower part stays green and thick, and if you live in an area with snow or ice storms, round off the top, keeping it as thin as you can, or the accumulation of ice and snow will break the top and open your hedge out. Watch for sections that seem to be yellowing, as branches can sometimes die back naturally. If you see this beginning, trim back those weak areas while they are still green, so that the surrounding foliage can spread into them. That way, if and when the weak branch dies completely, you will have a much smaller gap to fill in, and you will avoid the eye-sore of a gaping hole for several years. Sometimes too, trimming back an area that is weak will rejuvenate it.
Thuja Green Giant will live for many years, stretching into decades, and it can be maintained as a screen or hedge more or less indefinitely. The secret is to adjust your care techniques as they age, so you avoid problems down the road.