The Top Hat blueberry bush (Vaccinium corymbosum 'Top Hat' is a true dwarf of the high bush blueberry that was developed at the University of Michigan. It is petite at 24 inches in height and width, but a prolific producer. It is also known for its wonderful fall colour and when planted in the ground is hardy to --1.11 degrees C. Although it is said to be self fruitful, to produce an abundance of fruit it does need to be cross pollinated by a different variety.
Choose a site that receives at least six hours of full sun each day. Blueberries prefer acidic soil with a pH of 4.0 to 4.5. The soil should be moist but well drained.
Dig a hole twice as wide as the root ball and as deep as the container. Mix some organic material (peat moss, leaf mould, manure, or compost) into the soil that has been removed. The ratio should be equal parts organic matter and soil. Do not add fertiliser when planting.
Remove the plant from its container. If the roots are a dense mass score the root ball deeply in three places with the pruning shears. Prune any visible damaged roots. Place the shrub in the planting hole.
Fill in around roots with the mix. When you have filled in the hole half way, fill the planting hole with water. As it drains it will settle the planting mix around the roots. Continue filling in the hole and water again. Remove any flower buds to encourage good root formation.
Check the moisture level of the soil for the next few weeks. Blueberries have shallow root systems and are sensitive to water fluctuations. The soil should be moist but not wet. Blueberries need one to two inched of water per week during the summer. After mid September cut back on watering to encourage dormancy.
Top Hat blueberries make wonderful container subjects and have even been trained as bonsai plants. When planted in containers they will need some protection where winter temperatures fall into single digits. Top Hat Blueberries produce fruit on last year's wood so only prune right after harvesting.