Growing blackberries and raspberries in high tunnels increases yields. Berries grown in tunnels were larger than those produced in fields. Growing in high tunnels also makes the growing season longer for both floricane (summer fruiting) and primocane (autumn fruiting) berries. Floricane berries in tunnels bloomed an average of two weeks earlier in spring in tunnels than in fields. Primocane berries in tunnels could be harvested on average four weeks longer in autumn. Berries grown in tunnels also did much better in poor weather conditions and prevented significant loss of product. However, berries grown in tunnels need additional frost protection, as they bloom earlier in the year when frost may still be a risk. Frost can be prevented by covering plants with fabric (see page 10 of the Complete Project Report).