Seems crazy to be thinking about shifting plants as we head into winter, but Autumn is actually a great time to transplant trees and shrubs and other plants around the garden.
Transplanting can be for a number of reasons - maybe you've recently moved and what to bring some plants with you, or alternatively, perhaps you want to relocated some of the established plants in your new home. Perhaps you've planted something and since realised there is a way better spot for it. Or could be you just want change.
People are often turned off by the risks of transplanting - sometimes the potential catastrophe (dead plant) just isn't worth the potential rewards (beautiful, thriving garden). But with the proper understanding of your plants, and when the optimal time to do so is, it can be quite a straightforward process.
When to transplant?
The jury is still out on this one. The debate rages over Spring vs Autumn, although if our vote counts for anything, we're in the Autumn camp. Let's begin with when you definitely should avoid transplanting: Summer and Winter.
Summer: It's too hot! The sun is at peak intensity and the heat will mean your plants are extra thirsty. The last thing you want to do is be moving a plant, upsetting its roots and then encouraging it to settle in while perspiring like crazy. By Summer, you want your plants to be comfortable, with its roots firmly anchored in and drawing up all the moisture available to it - not trying to throw out new roots while keeping itself hydrated. If you absolutely must shift something in Summer, pick you day wisely. Overcast is great, or evening opting to do the hard yards later in the day when the sun is lower. Once transplanted, you'll need to be vigilante and keep the water up as a transplanted plant is going to be perspiring like crazy and won't have the established root zone to keep it hydrated.
Winter: Same same but different. Winter is when plant growth slows right down. Its cold. There isn't much sun and all your garden wants to do is settle in and wait until things start to warm up again. Shifting at this time of year makes your plant susceptible to stress. There are frosts to deal with, and the slow growth means it will be far more difficult to throw out new roots and get settled in.
So now you know when not to get shifting, we'll put forward the cases for Autumn and Spring.
Spring: Those advocating a pro-Spring stance on transplanting note that this is the time when plants are doing the most growing. Once moved, the plant will be keen as to get those roots out and exploring its new home. If done early enough, your hard work will mean that come Summer the plant is feeling comfortable enough to cope with the Summer heat. That being said, if the plant has not put pout enough new root growth by Summer, it could be a real struggle (and therefor extra watering for you) to keep it happy.
Autumn: Those of us campaigning for an Autumn transplant claim the shifted plant will be happy with the chance to take advantage of the wetter months and be able to really lock down those roots before the following Summer. You won't have to worry about watering like crazy and it will also mean that come Spring you'll be ok to fertilise your plant with the rest of your garden. There are some species that do not do as well with an Autumn transplant though - thick, fleshy rooted plants like Magnolias, Poplars, Oak, Birch and Rhododendrons are all better off being shuffled in Spring time.
Tips for Transplanting
With larger, more established plants, there are a few things you can do to make the move as stress free as possible. One thing is to take a sharp spade and cut cut through 1/3 of the root ball, in three sections around the plant. Do this approximately 2 months prior to when you want to transplant. Repeat this with each of the other thirds at two and four weeks later. Bu the time you're done, you should have cut a ring around the root ball. Doing this means that by the time you come to shift the plant, it won't have as much stress placed on the roots as if you'd gone and cut through them all at the same time, and those roots you cut through size weeks ago will already be starting to send out new feeder roots, so it will help set the plant up for its new home quicker.
The second thing you should think about is fertilising. You don't want to fertilise a newly transplanted plant straight away as the feeder roots need to establish themselves first. Adding fertiliser can force new growth when the plant isn't ready which in turn can stress out the plant. A low-nitrogen soil conditioner is a great option for transplanting as it adds beneficial microbes to the soil that help speed up organic breakdown and give life to the soil around the plant. It used to be the way that any new transplanted tree or shrub should be given rich, fresh organic matter to settle into. Now its believed that can actually stifle the spread of the plants roots, as they are reluctant to spread themselves and instead remain where in the unnaturally nutrient rich soil. By using the soil identical to the soil surrounding the plant (in other words, the same soil you dug out to create the hole), it forces the plants roots to explore further and better anchor it into position.