This is an international forum. f you really want to use an old fashion temperature scale only used by a few countries in the world plese state the unit used. 40 degrees would Cook most trees if used the international unit of measurement.
When I signed up on Bobsaiempire I missed the notice that must have been in pretty large letters that we would be flamed for not using metric. It doesn't seem to unreasonable to use English units when writing in English.
In most programming courses the first program is to convert F to C, or C to F. C =5(F-32)/9. 40F is about 4C, too cold for tropicals but just fine for winter dormancy for most trees.