Planting The Black Truffle
Here in Spain, the planting grid is 6 meter by 6 meter (approx. 18 ft. by 18 ft.) for a black truffle farm. That’s pretty much the international standard now a days. It is also the legal requirement to receive government grants in Spain. There are a number of reasons for this. You have enough room for a tractor to plow, it allows for little / no competition between the trees when they are mature and gives them their space to grow. But, more importantly there wont be excess shade on the ground in the winter but in the summer, it will offer the ground enough shade to keep them black truffles happily growing under ground in a cool and humid environment. Remember to leave enough room for a tractor to turn at the end of the rows and files of the trees. Usually 5 to 6 meters is more than enough room for the tractor to maneuver and turn around. If you are using a mini tractor, you can leave less room. Calculate between 250 to 400 trees per hectare using the 6 x 6 meter grid pattern, depending on how your land layout is. You need to plant a minimum of 250 trees per hectare in Spain to be eligible for government grants.
Planting The Tree
It is common practice now to plant your black truffle trees in the Fall rather than any other time of the year. Even thou certain people argue that if you can water your trees, you can also plant in Spring. Fall planting has a number of advantages over Spring planting. The tree is dormant or entering hibernation and suffers alot less the transplantation shock. Hence, you will have a lot less mortality rate. At 6 euros or more a tree thats something to consider. Normally the Winter is wet and rainy so your trees settle in better, so you dont have to worry about them getting water. There is even proof now that trees planted in Fall will need less water over their life time, suffer droughts better and even have a higher yield of black truffles. Once again, people argue this point but it is common practice in this area of Spain by the more successful black truffle farmers.
Now this is the fun part. Your back will love you after planting a massive amount of trees. The good news is that you only do it once!!!!! Dig a hole deep enough so that when you fill the hole in with dirt, the soil will cover about 2 fingers above where the potted roots are and be level with the surrounding soil / land. Remember to remove the root protector 1st before putting the tree into the ground. DO NOT try to untangle the roots, leave the root system alone!!!!!! I have heard people talking about untangling the root mass but you will most likely kill the tree by messing around with the root system. Place the tree in the hole, add some dirt about 3/4 way up the root system, pack the soil LIGHTLY with foot or hands so the tree stands firm. IF, you have access to water, add about 4 liters ( a gallon or so ) to the hole to remove air pockets. DO NOT REPACK THE WET SOIL!!!!! Fill in the hole with the rest of the soil till it covers about 2 fingers above the root system or the packing material the roots are in. Place tree protector tube over tree. Attach to stake with tie down. Last but not least, rake the soil up the sides of the tree protector into something that resembles a pyramid. Raking the soil up around the truffle tree protector helps to isolate the truffle tree from extreme temperatures. It also covers the bottom of the protector & will stop chimney effect within the protector. Repeat as many times you have trees. Rinse & repeat as the slogan goes.
There are a number of advantages in the use of tree protectors when the trees are young. The benefits far out weighs the small added expense. They help to maintain the soil humid, protects the trees from rodents, can keep it from freezing in the winter and baking in the summer. Another important advantage in using tree protectors is that there will be no lower branches on the tree trunk when it is bigger. The tree tends to grow as a ball of branches or crown leaving the 1st meter of the tree trunk bare which makes getting in close to the tree to till, remove weeds, collect truffles or to look for leprechauns far easier. The tree protectors are removed in Spring after the 2nd or 3rd yr after planting. Since they are made of plastic, chuck them in the recycle bin if you cant find any other use for them. VERY IMPORTANT - It is absolutely imperative that you make sure that the bottom of the tree protector is covered or under ground to avoid chimney affect. If hot air is allowed to enter the bottom of the tube in the Summer and escape from the top, it will kill the tree. If it doesn't kill the tree, the tree suffers enormously. Something you should try to avoid at all costs. Raking the soil up the sides of the protector into something that looks like a pyramid is how to solve this problem. This also helps to preserve the moisture in the ground and helps to isolate the tree from excessive cold in the winter and high heat in the summer. Another thing that you want to avoid when raking the soil up against the protector is leaving a deep gouge or donut where water can accumulate too close to the tree. Bring the soil about 3/4 the way up the side of the protector per the photo. You do this in Spring and Fall as you weed around the trees. Its natural for the raked up soil to settle after some months, just make sure that the bottom of the protector is always covered with dirt.
There are many different types of tree protectors on the market nowadays. The protectors in the photos above are the most common type of tree protectors used on black truffle farms in this area of Spain. This type of tree protector has a small air chamber between the inner and outer walls, which gives them their insolation properties. They have the added advantage that condensation accumulates in this small air chamber and will run down to the ground adding moisture to the soil surrounding the tree. Believe it or not, but you would be surprised the amount of water that the soil receives in this way.