Do you need to bring in new topsoil for planting trees and hedges or will the existing soil stock be OK? Most of the time it makes sense to work with what’s already there. Sometimes though, the soil on site needs a bit of improvement.
Trees and Hedges Are Planted For Future Generations
When you plant a tree or put in a hedge, you are investing in the future. It’s going to be there for a very long time. It’s up to you to make sure it will not just survive, but thrive in order that future generations can benefit from it.
That means giving it the best possible start in the best possible soil
When to Plant Trees and Hedges
The traditional time of year for planting trees and hedges is between November and March. That’s when the plants are dormant and less likely to be damage by being moved. For deciduous trees and hedge plants, that also means there are no leaves to wrestle with. The plants weigh less and are easier to handle.
Bare root trees and hedging plants are fairly cost-effective to buy. If you have a little more budget, you can opt for a container grown plant. These can be transplanted at any time of year. But be aware that they will need a lot of watering in the summer time.
Assessing Existing Topsoil for Trees and Hedges
The secret to longevity in trees and hedges is to give the roots what they need.
- Enough room to grow roots that will anchor them to the ground in all weathers.
- Enough room to grow as tall as possible without getting caught up in overhead power lines.
- Healthy soil bursting with the microbes and mycorrhiza to help feed the plants
- Uncompacted growing medium with plenty of tiny air pockets so that roots can breathe
- Well drained site that doesn’t get waterlogged in winter but doesn’t get too dry in summer either
- A suitable pH for the species you are planting
If you feel that the soil on site is lacking in any of those things, it’s up to you to correct the situation BEFORE planting your tree (or hedge).
How To Correct Problem Soil
Trees roots develop mainly in the top 30cm of soil. This is where there is most oxygen and therefore where the roots are best able to respire. It’s also where the majority of the soil wildlife is to be found. Vital creatures such as earthworms, nematodes, mycorrhiza and nitrogen-fixing bacteria. This ecosystem is crucial for the robust growth and plant health. Ignore it at your peril.
Provided the drainage is OK you can improve the soil by mixing it with really top quality growing media.
Too much clay or silt? Add fine sand and organic matter to improve drainage and open up the soil structure.
Too much sand? Add organic matter and a little clay or silt for strength and vigour.
Tree Planting Tips
When you dig the hole(s) for your new plants, make them the same depth as the roots but 3 times the width. Slope the sides of the hole and then score them with a garden fork so that you avoid “glazing”. Glazing is when the edges of a planting hole seal themselves so that roots cannot infiltrate them. It’s especially likely to happen in clay soils and has the same effect in the long term as planting the tree into a giant plant pot with no drainage holes. Nasty.
As you refill the planting hole, avoid compacting the soil. Yes, you do need to firm it in around the roots – but don’t go to extremes. This is especially important in clay based soils. If your natural soil is clay; there’s no harm in importing some good quality topsoil to mix with the infill.
For dry, sandy soils, it’s well worth mixing some water retaining gel crystals with the infill soil. They’ll help the plants enormously.
Finally, a layer of mulch around the base of the tree will help keep moisture in and supress the weeds. A natural mulch such as woodchip will also act as a soil improver and will nourish those all-important subterranean creatures