What Conditions Are Best for Granny Smith Apple Trees?

Climate

• Apple trees must endure a cold winter in order for flowering to occur in spring. This need for and process of receiving ample chill while dormant is a physiological process known as vernalization. Granny Smith apple trees need 500 to 900 hours of temperatures between 32 and 45 degrees F for vernalization needs to be met. Outside of winter, this apple tree responds well to warm temperatures and long growing seasons, but no more than 150 days of temperatures that exceed 86 degrees F.

General Growth

• In similar manner to other apple trees, the Granny Smith apple tree grows best when planted in a full sun location in the garden. It will tolerate partial shade, but the number and habit of the branches will be reduced, and tree vigor, growth, flowering and fruit production will be limited. Any nonalkaline soil that is moist but well drained suffices. Fertile soils are best, but applying granular fertilizers or organic matter to the soil can make any clay, loam or sandy soil conducive for good growth.

Threats

• While a Granny Smith apple tree can tolerate considerable drought after its root system is well established, excessively dry soil leads to abortion of fruits and leaves. This cultivar demonstrates above-average resistance to the common apple tree diseases of apple scab and fireblight. In rare instances, especially if the tree is weak and not in ideal growing conditions, these diseases may develop. Do not plant apple trees in soggy soils as it causes root rot. Once fruits begin to develop on branches, thin them out so the weight of apples doesn't bow and snap limbs later in summer.

Pollination Insight

• Although Granny Smith trees display attractive white flowers in spring, this apple tree is mainly grown for fruit production. Honeybees pollinate apple trees, and without pollination, no flowers later develop into apples. Do not spray pesticides that kill or dissuade honeybees from visiting blooming apple trees. Although one Granny Smith tree will yield some fruit from its own supply of blossoms, better fruit set occurs when multiple apple trees exist in the garden, resulting in thorough cross-pollination. Not all apple trees are a good cross-pollinating companion for a Granny Smith apple tree. Another nearby Granny Smith tree isn't helpful, and neither are apple tree cultivars Winesap, Jonagold and Mutsu/Crispin, according to Colorado State University horticulturists. Pollinating companion trees are best located no farther than 100 feet from the Granny Smith.