We have a gorgeous piece of land central-west Portugal. A lot of the land is shallow- soiled, less than a meter deep, on top of rotted granite. There were previously pines growing on it that were logged a few years ago. We want to plant food trees and are wondering what trees would be best suited. Thinking almond, fig, sweet chestnut. Does anyone have any opinions on the likely success or failure of these trees on shallow soil, or can anyone suggest any more suitable trees?
My soil is much less than a meter! The most successful trees I've found for shallow soils here are almonds and apricots, but I've also had success with cherries, plums, figs, peaches, pears and mulberries.
thats GREAT news because last autumn i planted two cherries and a plum in what i thought in retrospect was too shallow soil.. (less than a meter). mulberries, almonds, and apricots are the 3 next trees on my to-get list, so thats also great news! can i ask what you are under-planting with?
I find under-planting to be really tricky until the trees are big enough to give some shade. In shallow soil over the summer most under-story plants really can't cope very well and to be honest I'm generally far more concerned with keeping the trees themselves alive rather than worrying about having to fuss with more delicate plants.
Having said that, here are a few things you could try.
Lavender, grape hyacinth, welsh onions, galega cabbage, tronchuda cabbage, asparagus, nasturtium. I'll add more if I can think of any.
Oh, and modrono (Irish strawberry tree) is another one that is fine in shallow soil.
thats very encouraging to hear because here also our main concern is keeping the trees alive until the rain comes! but was feeling a bit inadequate permie-wise!! actually the questions i should have asked you are: what do you do to prepare the planting site? and what is the shallowest soil you would plant in?
yes, we plan to round up some baby modrono trees from the forest this autumn and try our luck with those too!
If I can't dig deep enough to cover all the roots, I give up and dig somewhere else. But I lose a lot doing things that way!
One thing I find useful is to use those 5 litre water bottles, often raided from a skip. I cut the tops off to make them easier to fill, poke a hole or two in the bottom, and use them as drip-waterers near the base of the tree. That way the water actually goes into the soil rather than pooling on the top. Also, mulch is your friend. Use as much as you can get your hands on, and cover as large an area as possible.
Here's a thread you might find interesting - the soil is a little deeper here than elsewhere, maybe nearer the meter you have. Burra's not-so-secret garden All the trees we planted there survived except for the apricot in the last photo, which was in very thin soil and in full sun.
I'm a little south of Castelo Branco, also in the Beira Baixa. So we're almost neighbours!
On our land we have olives, grapevines, nisperos, almonds, carob, oak, prickly pear, figs, wild asparagus, lavender, rosemary and thyme growing without any irrigation in very shallow soil. The amount of thisle growing here tells me that I should be able to grow artichokes.
When we plante our trees we dug a very big hole using a pick-axe - yes at times we were chiseling in bare rock! And we filled that whole with a mixture of the clay soil and compost. Not all our trees survived the first summer (glad to see we aren't the only ones Burra). A pomegranate, a citrus, a fig and a peach tree. What died was a chesnut, a mango, two other citrus trees, coffee and hazelnut (it actually think it was dead when we planted it...). The coffee survived the summer and died this winter - I don't think it liked growing under the carob tree... A volunteer avokado appeared in the vegetable garden and died with everything else when our house sitters bailed on us and left everything without irrigation for two weeks in August.
I am convinced that one of the keys to get trees to thrive here is planting from seed - which means that it will take quite a while to grow a forest on the other hand we can plant a lot at a very low price, with very little effort ( cf. the thread in here on growing trees in arid lands). Currently I am saving seeds from almost everything we eat and either planting it where the other trees died last year or planting in pots to transplant in the fall.
Another technique is to plant very densely and put shade cloth up and irrigate for the first two years - we are trying that too. In that setting I am planting ground cover - since I have shade already, they don't die from the heat (I also plant veggies there under the shade cloth, to maximize my use of the irrigation system. I've planted a mimosa for ground cover under a tiny citrus tree.
I'll get back in a few years to tell you about the results
I don't get to enjoy the same warm dry climate as you, but I do live on a ridge of ledge on a small rocky island. And I've been planting trees here for something like 13 years in poor shallow rocky soils over ledge.
I suggest you carry a heavy iron bar to test for the depth of the soil. You can just plunge the bar in and quickly ascertain an idea of the depth of soil and how rocky it might be before you dig a hole.
Also don't hesitate to build Swales and terraces to increase the depth of your soil.
My soil is so full of ledge pieces that it really benefits from being turned over and picked through a few times before planting. This results in a denser, cooler, and slower draining soil too. Adding compost and organic matter really helps absorb more water.
Mulching with some kind of organic matter and building a lip or dam around your planting to hold water make watering and retention of water much easier in fast draining soils. Make sure the trees have enough water the first year +!
Hope that helps a little...
Thanks so much for the input, permies!!
Useful and insightful info.
I have now collected apricots and saved their seeds to try germinating them. They are in a friends fridge for a fake spring as we speak!
When I planted the young trees we bought (cherry, apple, plum, and peach), I dug a trench in a circle around the planting hole, filled it with old dead branches and sticks (of which we have plenty after a pine-felling several years before we bought our land), and covered it back over with soil. I have heavily mulched each tree with a wide, deep mulch of straw. Oh, and I put a pvc pipe into each planting hole so that I can water as deep as possible.
We have just dug out one of the water pits on our land, and today I deposited the sediment on top of the straw mulch for each tree.
I hope they like it!
Because of this boiling hot weather we are having, I have upped the watering regime to every third day.
The trees seem happy so far!
May all your trees grow strong and fast and bear you fruit for decades to come!!