Blueberry plants with red leaves
My 2-year old blueberry plants had red leaves in spring and now. I added some coffee ground-enriched soil around them in spring. Could this be the problem? What should I do? The blueberries are sweet but small and dry out quickly.
Coffee grounds will provide some nitrogen (N) but not enough to manage what looks to be a significant N deficiency. You may also not be watering enough. I would start with a simple pH test. You can find simple test kits for $5-10 and any nursery dept. If the pH is higher than 6.5, your soil pH is too high for blueberries, and it shouldn't be lower than 4.5. We had a very dry spring (May, especially) and the plants require water to uptake nutrients. If the pH is in range, I would find an organic fertilizer for acid-loving plants (there are some specifically for blueberries, but rhododendron or citrus will do in a pinch.) First, make sure when you water, the water is reaching the roots of your plants. Drip systems or a soaker hose helps with ensuring you get that soaking action. Aim for your plants to get 3-5 gallons of water per week. Water first, then apply fertilizer and then water in the fertilizer but right now you only need to fertilize once for the rest of the year. Next spring, fertilize about a week after the leaves start to emerge (the plant can't really use the nutrients until the leaves are out.)
OSU Extension has the following publication for growing blueberries in your home garden https://catalog.extension.oregonstate.edu/ec1304 You may find this information helpful.