I have a blueberry shrub I purchased last year. It is called Tophat which is a dwarf variety. The first year it had a lot of flowers and produced some fruit. It was planted in a container. It spent it's time outdoors over the winter, I covered it with burlap to give it some protection and placed it beside the house. But this year I noticed it's not doing too good. It doesn't seem to be growing that much and the leaves look strange, green veins and lighter green/yellow around it. I have given it some fertilizer for berries and fruit (so it's a soil acidifier). However that was at the beginning of the growing season and I haven't touched it since. Before adding any more fertilizers, I decided to purchase a soil test kit so I tested it, and these are the results. pH = slight acid 6 or acid 6.5 Nitrogen = Low or Very low Phosphorus = High Potash = Low or Very Low When I planted it I also used regular potting mix (it was actually the Organic mix for Vegetable gardens by ProMix) When I dig into the soil it seems very moist like it holds onto moisture very well, maybe too well. I feel like changing the soil but not sure what mixture to use. I saw some mixes at the store for acid loving plants by Fafard but not sure if I need to do that yet. Does anyone know - What is the possible diagnosis based on the leaf colour? - What steps can I take to fix it? Thanks EDIT: I found out after some searching that "an overabundance of phosphate can interfere with a plant’s ability to uptake iron resulting in interveinal chlorosis, a yellowing of the leaves between the veins". This does sound very similar to my situation. Just not sure how to correct this. Too Much Phosphate | Root Simple
Based on the leaf colour, the chlorosis could be due to the low nitrogen or the high phosphorus or both, because high phosphorus also interferes with nitrogen uptake in plants. The soil is also too alkaline; blueberry plants like a pH of 4.5 to 5.2. I suggest replacing the soil with something more acidic and then using only acidic fertilizers.
A regular potting mix is pH neutral and not suitable for blueberries. Use peat based mix without added lime. Such mixes are available for acidophile plants.
