This heat pack will stay warm for approximately 2 days. Because we are using styrofoam boxes for shipping in cold periods, the content of the package will be kept warm long enough to arrive in good condition at your doorstep.
It is very advisable to choose this option when ordering in cold periods! Especially invertebrates need to be kept warm in transit using a heat pack. It can also be a safe choice when shipping plants, but it's not necessary. Also seeds can survive without a heat pack unless stated differently in the product description.