Although Thuja Green Giant is certainly the toughest hedging plant around, it still benefits from some attention, especially during the planting phase. Fall is also the best season for soil preparation, even if you are not planting until spring, so this seems like an excellent time to talk about preparing the ground for planting, either now, or in the spring
Should Thuja Green Giant be Planted in Spring?
This question is worth asking before we get down to the details of soil preparation, and it doesn’t have a simple answer. It depends a lot on where you live. If you are in the warmer zones, let’s say 7 and above, then planting in fall and early winter, while the ground is not frozen, is a smart choice. You may only have limited soil freezing, or none at all, where you are. If that is so, then you can plant all through the winter, especially if your new plants are well-established ones, coming to you in pots.
The colder your winters, the more you should consider planting in spring – at least once September has passed by, since that is an excellent planting month just about anywhere. As the soil gets colder, and soon freezes hard, the risk of some winter injury increases. So in zone 5, especially if you border zone 4, then spring planting is the better option once we reach October and November.
When is the Best Time to Prepare the Soil?
Having settled that issue, let’s look at our main theme, which is preparing the ground for planting, whenever it is going to take place. If you do opt for spring planting, then fall is the best time to prepare the ground. You probably have much less to do in the garden, besides rake leaves, so you will put more time into getting the ground ready. Letting a dug area rest over winter is also invaluable, so rather than a hasty job while the plants sit impatiently in their pots, do your soil preparation in fall and winter.
The Basics of Soil Preparation
The goal of good soil preparation is to create an environment for your plants that will encourage them to send their roots far and wide. As well, we want them to find lots of tasty treats along the way, that will feed them, and develop vigorous, sturdy growth. To achieve that we want a wide, deep area of the ground dug over. For a hedge planted in a single row, an area at least 3 feet wide should be prepared. If you are planting a double row, then make the planting area 18 inches wider on both sides than the distance between the rows. As this is commonly 3 feet, the prepared area will be 6 feet wide. If you are planting individual trees, or a widely-spaced screening, then you can prepare individual holes. These should be dug 3 to 4 feet wide, even though of course the actual planting hole will be much smaller.
As for the depth, most tree roots – even for large trees – are found in the top 12 inches, so ideally that should be the depth the ground is dug to. That is about the depth of a full-sized spade pushed completely down into the ground. When using a rototiller achieving this can be trickier, and we will look at that a bit further down.
That takes care of the first essential – space for the roots to spread. The second goal is to improve the soil by making it drain better, and by enriching it with materials that improve its quality in the long term, while providing a steady supply of nutrients to your plants.
Organic material is the ‘magic black gold’ for improving soil. Unlike fertilizers, it improves the soil itself, rather than just supplying plant nutrients. The top choice is well-rotted animal manure, from cows, sheep or horses. This is the mixture of straw and dung from sheds and stables, that has been piled up for a few months until it turns dark brown and crumbly. It has become increasingly hard to find, but garden centers often sell it in bags, or your local soil merchant may have it in bulk. In some areas there is a commercial mushroom industry, and the material used for growing mushrooms is an excellent compost. If you have your own garden and kitchen compost, that too is great. Other materials are available, different in different areas, so if you can’t find any of these, consult your local garden center for the best substitutes. Peat moss is acceptable, but low down on the list, since it has few nutrients, and can repel water when it dries. It also rots too rapidly, and the benefits are soon lost.
The ‘magic’ of organic material is that whatever type of soil you have, it will be improved. In sandy soil the material will increase the ability of your soil to hold water, and give it more nutrients. In clay soil it will open larger spaces, giving you better drainage. As well, natural gums and resins will bind together the tiny clay particles into bigger clusters, allowing air and water to move more freely through the soil. In all soils the gradual decay of the organic matter will act like a slow-release fertilizer, keeping your plants growing vigorously.
In some areas the soil is naturally low in phosphates, so super-phosphate or bone-meal are useful additions when preparing the ground. 5 pounds of superphosphate will be enough for a hedge area 100 feet long. Starter fertilizers for hedges, if you choose to use them, should be added, at planting time, not when preparing the soil in advance.
Digging the Ground
Once you have your organic material ready, rent the largest rototiller you can for a day (or two if the hedge is going to be very long). Begin by scattering that super-phosphate over the soil, it is important that it be dug into the ground, not sprinkled over the top of the area after the work is all done. Now spread the organic material at least 2 inches thick. On poor soil, you can easily double that. Dig the ground as deeply as you can. With a rototiller you may need to go over the area two or three times, working the tiller deeper each time, to get down to the full depth. The first pass over the ground might look good, but it will usually be too shallow. If you are leaving this bed until spring, leave it rough This allows the frost to penetrate, and if you have a clay soil, this will produce a better soil texture. If you are planting soon, rake it level and leave for a few days, if you can, for the ground to settle, otherwise delay raking until spring.
After all this work you deserve to stand back and admire the prepared bed, ready to take your new plants. You have done a fantastic job, and the growth and health you see in your new hedge will be your reward. Well done.