You only plant a tree once and it is the best opportunity you have to improve its root zone.
There is an old saying that you put a $1 tree in a $10 hole. Inflation may adjust the figures but it still holds true. Put tenfold the effort into planting and you set your tree up for life. A good root zone means it will grow a lot faster, fruit a lot earlier, be more productive and suffer from less pests and disease. The ramifications last for years.
I cannot emphasis enough how important planting is to your future tree.
Another old saying (these old guys knew a thing or two) is that the best time to plant a tree is twenty years ago, the second best time is today. This is true but there are considerations and advantages to the seasons.
Autumn - Planting trees in autumn is ideal. They get their roots well established with the winter rains and are all ready to put on a growth spurt the following spring.
Winter - Planting trees in winter when they are not actively growing reduces the shock of transplanting.
Many fruit trees are sold in winter ‘bare-rooted’. That means they have been grown in the ground, dug up and sent to you when the tree is in winter dormancy. Plant bare-rooted trees as soon as you get them.
If you need to keep them longer than a day you can ‘heel’ them into the vege garden. To heel, lie the roots in a shallow trench and throw enough soil over them to cover, and then water well.
Spring - After the last frost is ideal for trees that don’t like the cold. It means they can get established over summer to withstand the following winter. Citrus, macadamias, avocados, tamarillos are just some that don’t like cold weather.
Summer - Water is to a plant is like blood is to a human. Newly-planted roots haven’t had time to grow down to find water so only plant out in summer if you are prepared to water well and regularly until the rains come.
Preparing the Hole
You can prepare your hole anytime before planting your tree – a year or two in advance even. If you don’t have an adequate source of compost this allows time for the ingredients to mature.
How much effort is required depends on how good your soil is.
The easiest way to work out how good your soil is, is to count your worms. Put a 20cm x 20cm spadeful of dirt on a tarpaulin – if you find 50-80 worms you have great soil and don’t need to worry too much. Anything less and every bit you do to improve your root zone will be beneficial to your tree. A soil test will establish your mineral levels and you can do a visual soil assessment yourself. Download the guide here http://www.landcareresearch.co.nz/publications/books/visual-soil-assessment-field-guide
How you dig your hole will depend on your soil and climate.
If you are doing a lot of trees and don’t have good soil, consider hiring a small digger for a day. It makes life a lot easier and is great fun. Otherwise you can use a posthole borer or a spade and sweat.
In sub-standard soil your tree will benefit immensely if you dig your hole 1m x 1m x 1m deep. Yes, that is a big hole for a little tree, but don’t you want it grow big?
Below the hole you can bury any dead animals, road kill or offal. My best-producing plum is the headstone for one of my dairy cows. A great way of marking her grave and fertilising with blood and bone for years.
If you have clay soil, or find a hard layer (pan) as you dig your hole, make sure water will drain out the bottom. Fill the hole with water and see if it is gone by the next day. If not, you have to create drainage, bore down below the hard pan or sideways if on a slope.
(If there is a hard clay pan throughout your property, consider the benefits of getting a contractor in to ‘rip’ it. He will score deep into your soil, breaking through compacted layers. There is a science to doing this correctly; along the lay of the land in dry climate to retain water, downwards in wet climates to aid drainage – a good contractor can advise you on this.)
Roughen and square the edges of your hole. Having a smooth round hole (like that made by a posthole borer) means the roots of your tree could grow round and round instead of outwards.
Sprinkle gyspm around the edges of the hole – this will improve the clay and blur the edge of your nice hole with the surrounding soil.
Mix into your hole:
- compost – ideally make the hole 50-50 soil and compost. If this is not available, mix in some (say 25% or more, depending on how soon you are going to plant the tree) of whatever you have: tree mulch, animal manure, seaweed, fishwaste, lawn clippings, leaves etc and in the middle of the hole, put some good composted soil. As well as immediately feeding the new tree, the compost will boost the mycorrhizae and bacteria needed to decompose the other matter before the roots grow to it.
- gypsm – sprinkle a couple of handfuls in to bind the tiny clay particles together
- minerals – if something showed up as lacking in your soil test, add a small amount into the hole. (Little and often is the way to go when adding minerals.)
- water crystals – these are jelly-like crystals that absorb and retain water. They are expensive but make a huge difference in supplying water to the roots through that first critical summer. Soak them first is a weak solution of liquid fertiliser or water so they are swell. One to two large double-handfuls for a 1m2 hole. (Don’t use too much or they can cause excessive soil movement contracting and swelling with moisture.)
- Sand – If you have it, mixing a bucket of sand into the hole is a quick way to improve clay soil structure.
This is all about increasing your water retention and nutrient levels.
Mix into your hole compost as per for clay, but increase the water crystals to three large double handfuls per 1m2.
Sandy soils in general have a lower mineral retention than other soils, so concentrate on correcting any deficiencies. Without a soil test you are working blind and do not know what you need. I highly recommend doing at least a basic soil test as soon as possible. I could not afford it when we first moved on to our block, and two years later when I finally got one done I wished I had had one from the beginning to compare with. My soils had improved visually, but it was only after the test that I knew what was lacking and needed adding.
The basic soil test at Hill Labrotories costs around $80 (per sample). Phone 07 858 2000 or see here.
If you want to increase overall nutrient levels, use a variety of natural fertilisers which contain a range of minerals (e.g. manure), but keep them away from direct contact with the tree roots until they have composted.
Your drainage should be good, so you do not need to worry about soil structure, just nutrient levels.
Mix into your hole the compost, minerals and water crystals as detailed above for clay soils.
Mix your additives in well (trust me, a digger really is great). Your soil level should be quite raised from the surrounding ground, but this will subside as it settles again.
If you are living in a dry climate, you want your final hole to be concave to dam water and direct it to the tree roots so excavate some soil out.
Conversely, if you live in a wet climate and/or are planting trees that are susceptible to root rot (avocadoes especially) you want your final tree to be up on slight mound so the roots do not drown in winter. So you may need to add extra soil.
Remember that a freshly dug hole will settle a lot.
It’s a bit like painting a wall – there’s more work in the planning and prep than the actual planting – but it is worth it.
Finally… planting the tree
Soak your tree in water, preferably with a weak solution of seaweed fertiliser or willow water (link to article about how to make liquid fertilisers) for a couple of hours before planting. Do not soak more than six hours or you will start drowning your plant.
Carefully remove the pot with minimum disturbance to the roots. This is especially important with avocados who do not like their private parts being played with.
If the tree is rootbound (has been in the pot too long and roots have grown round and round) carefully tease out as many roots as you can so you can direct them outwards.
If the soil is loose, try to disturb it as little as possible and settle the tree directly into the hole with all the soil from the pot.
Ensure bare-rooted trees have nice loose soil sprinkled in and under their roots – you don’t want any large air pockets left between the roots.
Face the biggest and strongest roots, and/or branches, towards the prevailing wind.
Whatever the ground level on the plant was before, is what you want it to end up now. Burying the trunk too deep in soil can cause the bark to rot and ringbark your tree. So plant your tree high in the surrounding ground and stamp down around the roots to press out air pockets and water well for the same reason (as well as watering the plant). About 20 litres of weakly fertilised water for the first soak. By now the tree’s previous ground-level line should be level, or still slightly proud of, the surrounding earth.
Formative shaping is the most important pruning you will do in your trees life, and doing it as you plant it out reduces the stress on the roots. Bare-rooted trees have had their roots reduced drastically in the lift and sale process, and you need to decrease the canopy proportionally to reduce the demands on the recently-shocked roots. Even if the tree is bare of leaves and in dormancy, do not be fooled into thinking it is not doing anything – there is still a lot of scientific processes going on in your little stick.
Ask the seller of your tree if they will prune it for you, or read up here about pruning in detail.
Most orchard trees require sunlight for fruit and you don’t want them to get too tall, so the most common method is to take out the top centre of the tree so it will develop an open vase-like shape.
This means leaving two-four strong branches or buds and cutting the rest of the tree off. You should be reducing it to about 120cm in height if you plan to mow underneath the tree or lower (80cm) if not. Cut on angle, a few millimetres above the topmost branch/bud, and reduce the remaining branches by two-thirds, once again cutting just above a bud, preferably an outward or upward-facing one, as this is the direction of next year’s growth.
You may have reduced your tall tree drastically, but you have set it up ready to grow into the shape you want as well as reducing the load on the roots during their time of stress. The tree will repay you by establishing healthy roots over winter and putting on good strong growth in spring.
As well as the general and water retention benefits of mulching, surrounding a newly-planted tree with mulch prevents surrounding grass or plants from crowding the new plant and stealing it’s water, nutrients and sunlight.
You can use a lot of materials for mulch, many of them free – see our mulching article for ideas.
You are wanting to prevent the wind from moving the tree around too much while it establishes its roots. Depending on how windy your area is, tying it to one stake on the windward side might be sufficient. I prefer to use two waratahs on each side and two lengths of old bicycle tube, each tied around the tree and stake in a figure 8. This allows the tree some movement (which will strengthen it), but enough support in strong winds.
Do this the day you plant it – otherwise something is sure to have eaten it off by tomorrow!! As well as your own stock and pets, there are rabbits, possums and pukekos who can destroy your plants overnight. See our file on protecting trees.
Really. It’s a lot of work to plant a tree, and what I have outlined above is the ultimate. You can of course, dig a hole and bung a tree in and hope it grows. It probably will as trees are natural adaptors and survivors. And I have seen the results of such treatment – six years old and spindly, sickly, sticks producing, if the owners are lucky, two fruit.
How fruitful (literally) your endeavours will be depends entirely on your soil and climate – if both are prefect you can get away with doing little, but if neither is optimum, every effort will produce a healthier tree. A healthier tree is naturally strong enough to withstand pests and disease without the need for sprays and produces more, and more nutrient-dense fruit. Feeding the roots is how to you get a healthy tree and it is only at planting time that you have the opportunity to modify the root zone – it really is worth the effort.