The canopy
The bones of any landscape are the largest trees. In a food forest, canopy trees – if you have them – should produce food or provide shelter.
Chestnuts and English walnuts are good options. The crop drops to the ground (no need to worry about climbing them), and you get a wide canopy. The drawback is you end up fossicking amongst other plants to gather the nuts.
Another problem is how much the established root systems of big trees will dominate and consume available nutrients. I put delicate tropical plants under some existing plane trees for protection from winter frosts. Unfortunately, I underestimated how much the plane tree’s roots would suck the nutrients from the soil.
To remove the plane trees, without destroying the precious avocados and bananas growing under them, will cost a fortune.
Sheryn’s tip:
choose canopy trees very carefully. Wide canopies produce a large amount of shade, and those with shallow, wide root systems will take away nutrients from plants below.
SHELTER TREES
Shelter trees are essential if you’re planting on a windy site, but too much shelter can be detrimental.
Trees planted solely for windbreaks often became a nuisance in time when they:
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create too much shade;
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steal nutrients from production trees/ plants;
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create still, humid conditions that allow pests and diseases to thrive.
My block isn’t a high-wind zone, so I planted feijoas on the north-west corner and large Japanese plums on the windward western side. They produce a lot of fruit, even in bad years, and the ones I can’t reach are good bird feed.
Macadamias and hazels make good shelter trees too.
Bamboo is a quick-to-establish wind shelter. The edible Moso bamboo is a spreading type, but not overly invasive and can be kept under control if you cut off the big shoots that appear each year.
You can eat them too.
Another good option is a mixed hedgerow containing the more fringe food trees, such as elder, hawthorn, maqui berry, rosehips, tagasaste, tangshi, and fuschias. They’re interesting, don’t grow too tall or wide, and are productive, even if it’s just as food for the birds.
Tall, quick-growing alders are often dually utilised as a windbreak and to fix nitrogen in the soil.
Sheryn’s tip:
The trees around the edges of your food forest get the advantage of space and sunlight. I should have put my stone-fruit around the outer perimeter where breezes would inhibit leaf curl and brown rot.
NITROGEN FIXERS
Some food foresters contend that at least 25% of trees should be nitrogen-fixers. These host nitrifying bacteria and produce excess which helps to feed the surrounding plants.
All plants host some nitrifying bacteria, but some create a lot more than others.
Sheryn’s tip:
Common nitrogen-fixing plants include: Canopy – alders, locusts, wattle Sub-canopy – tagasaste (tree lucerne), carob, liquorice Herbal/climbers – anything in the legume family, eg peas, beans
Ground cover – clover