Method for avoiding frost damage in crops and/or for improving the fructification at low temperatures and device applied with such a method

1. Method for avoiding frost damage in crops and improving the fructification at low temperatures, comprising periodically heating and cooling the air at the site of the crops with a minimal temperature variation of 0.2° C. and wherein the heat is supplied by drawing in the ambient air, heating the drawn-in air and distributing the heated air over the crops; and

wherein, in order to avoid frost damage, during the entire period of the temperature variation, the temperature of the air at the site of the crops stays under the temperature at which the crops are no longer frost resistant in the absence of the aforesaid steps; and/or

wherein, in order to improve fructification, during the entire period of the temperature variation, the temperature of the air at the site of the cross stays under the temperature which is deemed suitable for fructification of the crops in the absence of the aforesaid steps.

2. Method according to claim 1 , wherein the heat is just sufficient to ensure that the smallest temperature variation at the site of the crops is 0.2° C.

3. Method according to claim 1 , wherein the period temperature variation at the site of the crops lasts 10 minutes at the most.

4. Method according to claim 1 , wherein the period temperature variation at the site of the crops lasts at least 4 minutes.

5. Method according to claim 1 , wherein in order to distribute the hot air over the crops, a fan is provided, having an inlet and an outlet, and wherein the air is periodically heated and cooled by rotating the outlet.

6. Method according to claim 5 , wherein the outlet extends mainly parallel to the ground.

7. Method according to claim 6 , wherein the outlet rotates round a vertical axis.