The climate in Illinois is ideal for growing cherries. Illinois' growing zones range from 4 to 6 from the north to the south and sour cherry trees thrive in just that range. Sweet cherries need a bit more warmth (growing zones 5 to 7), but they do well in the southern regions of the state. Whether you choose a sweet or sour cherry variety, pick a cultivar that grows well in your area. Cultivars that do well in Illinois include Hally Jolivette, Higan, Sargent and Yoshino.
Have your soil tested by your local county extension office. Ask for the home and garden soil test, which will reveal the pH of your soil (cherry trees need a pH that falls between 6.2 and 6.8) and whether it contains enough nutrients to support your tree (cherry trees need magnesium, boron and zinc to thrive).
Choose a site. Cherries grown in Illinois need full sun, and a spot with good circulation and well-drained soil. And, especially in northern Illinois, avoid planting your cherry tree in a depression or around other buildings or shade trees where cold air settles.
Plant your sour cherry in early spring to get the most out of the Illinois growing season. Dig a hole that is twice as wide and twice as deep as the container that your cherry sapling is currently in. Fill the hole with water and then allow it to drain. In the meantime, mix the excavated soil with an equal amount of aged compost. Carefully remove the cherry tree sapling from its container and loosen its roots by carefully pulling them away from the root ball. Cut any dead, broken and container-bound roots with a pair of sharp pruning shears. Plant the cherry sapling in the hole so that the soil mark on the sapling is level with surrounding soil.
Water the planting area. Run a slow hose at the base of the sapling until the planting area is thoroughly soaked. Keep the planting area moist until the cherry tree has established itself and begins producing new growth. Then only water the cherry tree when the top 3 inches of the soil are dry in summer and fall. After the tree loses its leaves, water it less frequently and stop watering completely in winter when the tree is dormant. Also stop watering just before the cherry tree bears fruit and do not resume until you have harvested the cherries.
Spread a 3-inch layer of organic mulch around the base of the tree. Remove it after two years when the cherry tree is firmly established.
Prune your cherry tree in early winter when conditions are dry. Remove any dead or non-productive twigs and branches, and those that cross over one another.
Fertilize your cherry tree. Until your tree begins to bear fruit, it needs no fertilizer at all. When it begins to fruit, it will need an annual fall application of a 12-16-12 fertilizer (28 g per square yard).
Harvest the cherries. Wait until the cherries turn fully red, black or yellow (depending on the variety) before harvesting them. They sweeten during their last few days of ripening. Pull the cherries off the tree with their stems still attached (take care not to remove the fruit spur--it takes 2 years to grow a new one).