How to Grow Black Truffles

How to grow truffles is a question with a plain answer and a long timeline: you plant a tree that already carries the black truffle fungus on its roots, and you look after that tree for years before anything comes out of the ground.

This article follows what a grower in Spain does, in the order he does it, with his own numbers.

The tone is his: the truffle is beautiful, but the aim is kilos.

Start with the tree, not the truffle

Black truffle, Tuber melanosporum, is not sown like a vegetable. It lives on the roots of a host tree, and the two feed each other in a symbiosis. If the tree lacks food, the grower says, it will not give any to the fungus.

So growing truffles means buying an inoculated tree from a nursery that checks its batches, and then keeping that tree healthy. Everything else follows from that.

How many trees, and where they can grow

The grower plants 300 trees per hectare. For a forty-hectare project, his own arithmetic was about 12,000 plants.

Where they can grow has widened. Twenty years ago, he says, planting truffle in La Mancha was unthinkable; today there are producing plantations there, including one he saw with twelve years of age. In that soil the truffle forms at about 50 centimetres deep and takes more work to lift.

His answer to “can I plant here?” is cautious: he would say yes, but it carries a lot of complexity. The soil is analysed and, more importantly, interpreted before anything is planted.

When to plant

Spanish technical sources place the planting window from autumn to spring, with planting holes opened from November to March and hard frosts avoided. Nurseries add that spring planting is on the rise because the plant leaves with its inoculation at its peak.

Water: the part most people get wrong

Irrigation is on the grower’s list of essential works, and he notes that only a handful of companies in Spain specialise in truffle irrigation. Most people call a plumber they know instead.

The reference system in the sector is micro-sprinkler irrigation, with a published dose of 20 to 25 litres per square metre every 15 to 20 days from June to August, less whatever rain has fallen. In the first years the water only supports rooting; productive irrigation matters from year five or six. Too much water does as much harm as too little.

The timeline, without decoration

The grower gives the years as they are. If everything is done right, the first truffles appear at five or six years, in token amounts. Commercial production starts at eight to ten.

The plantation begins to earn at ten to twelve years, peaks between twelve and eighteen, and a tree can produce until about thirty. He calls it a very long-term investment, and he means it.

• Years 5–6: first truffles, token amounts.
• Years 8–10: commercial production.
• Years 10–12: the plantation starts to earn.
• Years 12–18: peak production.
• Up to year 30: productive life.

What a hectare really yields

The grower designs his plantations to reach the highest yield possible, with 200 to 250 kilos per hectare as the design target. That is a target, not a promise.

What he calls ideal in practice is 50 kilos per hectare, and he is clear that anything from 20 kilos upward is already a good result. Anyone promising more than that is selling something other than truffle.

Why some plantations never produce

The grower says the sector lacks professionalisation: people take a plot and put the plants in any old way. Some plantations produce nothing because something was done wrong or a detail was missed.

The detail is usually one of the things above: the plant, the soil, the water, or the pruning. Growing truffles is not difficult to describe. It is difficult to do without skipping a step.

The first step

The first step is the plant. Where it comes from, how it was checked and how many you need are covered on the page about truffle trees, which is where an order starts.

Where this article leads:

• Truffle Trees for Black Truffle (Tuber Melanosporum)
• Inoculated Truffle Trees: How Black Truffle Mycorrhiza Works
• Black Truffle Farming: What a Plantation Costs and Yields
• Black Truffle Orchard: Planting, Pruning and Pests