Blueberries are distinct among fruit crops in some of their requirements. They require a low pH - acidic conditions and will not grow under alkaline conditions.
Blueberries are impossible to grow in conventional soil gardens with an alkaline pH regardless of the soil amendments added. In hydroponics this is easier to control than blueberries grown in soil, but does require diligence.
pH ... Keep in mind that the requirements of Soil ph is not the requirements of Hydroponics pH
Do not confuse Hydroponic ph and Soil pH. Optimal pH for a standard nutrient solutions is between 5.5-6.0, although most plants can still survive in an environment with a pH of between 5.0 and 7.5. If your nutrient solution or growing medium is too alkaline or too acidic many of the vital Hydroponic Nutrients will be wasted , un-absorbed by the plant. Blueberries MUST be kept at a Ph of 4.5 to 5.8 and 1260-1360ppm.
Nutrients - Sulfur
Blueberry plants use high amounts of sulfur, which is generally not lacking in a hydroponic system for normal plants, but blueberries are not normal plants, they require elevated sulfur levels. The normal range of sulfur in the initial water is anywhere from 10 to 80 Parts per Million [ppm], more comes with standard nutrient formulas. However blueberries frequently require more than standard formulas can furnish. Adding sulfur to the solution for blueberry plants can be problematic as sulfur is not water soluble.
Signs of nutrient deficiency are the yellowing of the leaves and veins. Leaf tips will frequently yellow and curl downwards. A uniform pale green yellowish chlorosis throughout the entire plant. The younger leaves generally appear paler much earlier than the mature foliage. Stunted growth, less branching are other symptoms.
Sulfur Prills commonly used in a sulfur evaporating system are one method of adding much needed sulfur to blueberry plants, another method sometimes used is sulfate salts of other major nutrient elements, in particular magnesium and potassium -Magnesium Sulfate or Potassium Sulfate. Epsom salts are recommended for use on blueberry plants grown in soil, in a hydroponic system it is not useful and will in all likelihood foul up your nutrient solution big time.
Another method I've experimented with, that seems to be working, is companion planting blueberries with Garlic. Garlic accumulates sulfur, and some is released in the solution which is readily absorbed by the blueberry plants. It's not a quick fix, but is helpful in the long run.
Growth Technique and Conditions
The berries that I grow, I frequently put into inexpensive poly bags ~ Grow Bags ~ with a mix of Perlite and vermiculite, 70% Perlite 30% Vermiculite. Perlite does not retain much water, it draws it up via transpirational pull, Vermiculite retains too much water - with Blueberries and other berry crops ,you want to avoid too much moisture near the root base for extended periods due to the high susceptibility to root rot. A blend of these 2 mediums seems to do the trick
Although the perlite vermiculite blend is best - other mediums such as expanded clay will also suffice.
A drip system is best, and any surplus solution that drains from the bags goes directly into a waste receptacle which gets reused for one cycle, and one cycle only, and then goes onto my outdoor compost. I find this much more time efficient than endeavoring to constantly maintain nutrient levels.
Specific plant requirements will vary slightly from one variety of blueberry to another. The amount of light and nutrients for example - but in general most blueberry cultivars have similar needs.
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It is best to plant at least 2 or more plants of each variety you choose.
Staggered ripening intervals can also be advantageous if wish to harvest continuously.
Blueberry plants take 3-5 years to get established and bear good yields, don't expect much of a harvest - if any at all - the first annual cycle - by the second you should start getting a very modest amount.
The best option for lighting is a High Intensity Discharge lamp,[HID] fixture. They are among the most intense and most closely simulate sunlight. Fluorescent fixtures will suffice with decreased yields.LED Lights will also work , they are not as good as the HID, but tend to be more cost effective. You may also want to consider using Mylar Reflective Film to optimize your use of available light to the plant.
12 -16 hours of light daily is best , the more light the better, but never 24/7. Like all plants they do require several hours of darkness in each daily cycle.
See: Grow Lights
In a conventional garden, blueberries need a growing season of around 140 days. In a hydroponic setting this time can be shortened - depending on the conditions you provide, to allot for multiple harvests. However keep in mind that any blueberry plant grown hydroponically should be placed into a simulated winter for at least a month annually.
Dormancy and Pruning
Dormancy in blueberries can be averted, however,they require a cold season in order to adequately set fruit. Basically , there is little chance of harvesting from any single blueberry plant year round - which is another reason to have several. Averting dormancy in blueberry plants will lead to a plant that grows lush vegetation but no or very little fruit.