High density tree planting, where two or more trees can be planted in the same hole to form a single canopy with multiple trunks, is drawn from the system of Backyard Orchard Culture, developed by the Dave Wilson Nursery of Central California.
In this system, fruit trees are kept small in size by planting them closer together, and by summer pruning them. This creates a high-density planting which provides many benefits, such as:
- Optimum use of limited space – many small fruit trees can fit in the space that one large fruit tree would normally occupy.
- Greater variety – when space is used more efficiently, more types of fruit trees can be grown, or more varieties of the same fruit which can serve as pollinators to maximise yields.
- Sensible production – smaller trees can produce a large enough crop to provide for a family’s needs, without the excess and waste.
- Extended harvest season – in the same space as a single large tree, a high density planting of early, mid and late varieties of one type of fruit can be planted, or various different kinds of fruit with consecutive harvest periods throughout the year.
- Easier fruit harvesting – when trees are kept as high as our arms can reach or a little higher, fruit picking is much more convenient.
- Easier orchard maintenance – low fruit trees are much easier to spray, prune and net, and they requiring far less effort and materials to maintain, and eliminate the need for specialised equipment such as ladders, pole pruners and long-reach fruit picking equipment.
How Many Trees Can Be Planted Together in a Single Hole?
It’s possible to plant two, three or even four trees into a single hole using this many-in-a hole Backyard Orchard Culture planting system.
When selecting trees to plant together in a high-density planting, it’s essential to select trees of similar vigour, to make pruning more manageable and prevent one tree from crowding out its companions.
Pictured below are two young fruit trees, planted two-to-a hole, and spaced 45cm (18”) apart. They will eventually grow into a single canopy, but with two separate trunks, which is far more resilient than a dual-grafted tree, because there are two whole root systems supporting tree-sized canopy.
How Far Apart Should Trees Be Planted in a Many-to-a-Hole Trees Planting?
In high-density plantings, the closest that trees should be planted is 45cm (18”) from each other, and no closer. The furthest they should be planted apart is 90cm (36”), as any further, and they will simply grow as separate trees, each with their own small canopy, if they’re summer pruned to dwarf their growth.
The same distances are used whether there are two, three or four trees planted in the same hole, and also if trees are planted together in a line to form a hedgerow, or if each tree is pruned into a columnar cordon form.
Can Trees Be Planted Closer Than 45cm (18”) in High Density Plantings?
In high-density planting used in Backyard Orchard Culture, the recommended planting distance is 45cm – 90cm (18” – 36”).
Why not plant trees closer than 45cm (18”) from each other?
I’ve seen a few instances where it’s been recommended to plant trees very close together, which is a very bad idea for two reasons:
As trees grow, their trunks progressively thicken. If the trunks touch, the bark will scrape as the trees sway in the wind, or they will fuse together in a form of graft. If bark is damaged, it creates an entry point for diseases and pests. If trees fuse together, any disease in one will spread to the other. Furthermore, if there is a narrow crevice between two closely-growing tree trunks, debris can gather there, and wet organic material can rot and cause the bark to rot away also.
The second reason is structural, as shown by the diagram below. When trees have a bit more space between them, there is more space between the two trunks for the canopy of each tree to grow into, moving more of the weight of the canopy a bit closer to the middle.
If trees are planted very close together, there is very little space between trunks for the canopy to grow into, so most of the canopy will hang off to one side, making each tree extremely lop-sided, with very uneven load distribution. A tree canopy heavily weighted to one side is prone to being blown over by heavy winds, or collapsing under increased canopy weight due to a heavy crop load. A wet canopy is heavier than a dry one, and the combination of rain and wind can have a similar detrimental outcome.
As additional reference, I’ve included a copy of the original document “Backyard Orchard culture (Summer Pruning Fruit Trees For Size Control)” by Dave Wilson Nursery, which, in case it ever becomes unavailable, can be viewed or downloaded here.
Hi Angelo
Thank you for all your good work. I triple planted a number of citrus trees about 6 years ago now into sandy soil (I live on North Stradbroke Island). (Eureka lemon, Tahitian lime and kaffir lime in one set, early + late orange and mandarin in the other grouping. I have added compost and mulch regularly and grow herb groundcovers and sweet potato underneath them. I haven’t had much success with fruit production and now think they are closer than the recommended 45cm minimum. My pruning too could definitely be improved. My main query is should I remove any of the trees to allow for a bigger spacing and are the feeding requirements higher than normal with multi plantings or do you just treat it as the one tree? Thanks Sherelle
Hi Sherelle, thanks for your question. You have done the right thing with the sandy soil by using compost and mulches to improve its nutrient and water holding capacity. Growing shallow rooted herbs provides a natural cover to keep the roots cool in summer, but I would definitely not grow sweet potatoes underneath the citrus trees.
Root crops shouldn’t be anywhere near citrus trees which have shallow roots and are sensitive to root disturbance. Additionally, the citrus, which are heavy feeders, will compete with the root vegetables for nutrients, which are also heavy feeders!
The trees are too old to relocate and space further apart. That’s something you could do in spring, and with a single tree, but with many trees to a hole, their roots would be very hard to separate, and would be damaged too extensively trying to do so. It’s better to just prune them to size in spring, then through the warmer growing season as needed.
When feeding a many to a hole tree planting, feed it according to the area it occupies. Most fertilisers will have an application rate per square metre, just use that. A multiple planting will therefore be treated as a larger single tree. 🙂