Thanks, Eric. It is cold here, but I think the reddish brown color of my foliage is the tale tell sign. I do have an abundance of magnesium in my soil - so much in fact that I've been exploring ways to reduce it by increasing the calcium content. When I transplanted, I did add plenty of peat to the soil to bring down the pH, and I know suspect the peat is so dominant that the uptake of magnesium has been slowed down. I'll keep monitoring.
Mikkle

We have some blueberry shrubs with red-brown leaves, and I expect these to green up within a month or so. Here in Madison, Wisconsin, our native soil has a pH around 7.6, way too high for blueberries. I am using agricultural sulfur for lowering soil pH, and testing soil samples with several indicator dye solutions, including bromocresol-green, which is yellow at pH = 3.8, and blue at pH = 5.4. I also apply dilute solutions of fertilizer, either Miracle-Gro Acidic, or Schultz's Plant Food Acidic, several times in the spring. I am inclined to think that the red-brown leaves are normal-OK in the spring, but I know that they are not OK during the summer. So I will wait & see what develops. In your case, I would be checking soil pH, there really is no way to guess what's going on. If the pH is too high, over 6.5, you can immediately lower pH with a mixture of 5% white vinegar and tap water, typically 6 fluid oz vinegar per 4 gallons of water.

Eric,
I was wondering about the effect of the sulfur products on the fungi, in particular around the blueberries. I've heard it kills them off, making less nutrients available to the shrubs and therefore, less sweetness, etc. Any experience to shed on this?
Mikkle

Actually, chilled soils don't inhibit loading of Mg any more than they do other nutrients, except maybe P. The most common cause of purple leaves, very common at this time of year, is a deficiency of phosphorus (P) because of cold soils. P is required to make ATP and ATP is needed to turn sugars to starch and to load sugar into phloem for transport. No P > no ATP > no move sugars/starches > anthocyanin (purple pigment) builds up > plant turns purple. The most frequent cause of a P deficiency is cold soils, which is why so many plants planted out too early turn purple. Don't use your hi-P fertilizers on your containers (ever) - can't say what is going on in your garden or berry patch.

A P deficiency is not the only suspect cause of purple leaves. Nearly any environmental condition that puts the brakes on growth and the accompanying use of sugars, but does not limit sugar production (photosynthesis) can cause anthocyanin buildup and purple leaves.

If only the outer edges of the leaves are purple, it may be a K or Mg deficiency. If the center of the leaves are also purple, it could be too much Ca in the soil or the result of too much water in the soil blocking uptake of P and/or Mg.

All that if it isn't red leaf disease (Exobasidium vaccinii - look for white under the leaves) or possibly blueberry/hemlock rust, which turns leaves red.

Al

Since I can't see the blueberry leaves that the original post refers to, I will refer only to the red-brown leaves on our blueberry shrubs here in Madison. At this time, maybe 1/3 of the leaves on several shrubs are partially, but not completely red-brown. The remainder of the leaf is green. The affected leaves tend to be higher up & farther out on the branches. The leaves that are closer to the roots are mostly green. I think this is a developmental issue that will resolve itself in a few weeks. I will report back with what I can see happening in a week or two.

Thanks, Eric and Al. I'll keep an eye on my berries.

Our blueberry shrubs are now covered with green leaves. Maybe 5% of the leaves show a small amount of the red-brown tint. So the problem is nearly gone. I have seen this before, and it can get pretty extensive. Our shrubs are in soil with pH between 4 and 5.5, and they have been fertilized several times this spring. It could be that the fungi in the soil require several months to develop, and until they do, the shrub does not take up enough nutrient. But that is speculation, I don't know the cause of this problem.

Leaves of any plant that turn reddish in color do that for a variety of reasons, but at this time of year that will mostly be because the soil is too cold for the Soil Food Web to be working and supplying the plants with the nutrients they need. More often than not cold soils do not allow plants to uptake Phosphorus and that is most often indicated by the leaves turning a reddish color. A Magnesium deficiency is indicated by chlorosis, yellowing of the leaf. This is usually a short term problem that needs no "fix" since it will cure itself as the soil warms. If this does persist them a good, reliable soil test will be needed.

Hi,

I started a backyard blueberry garden with 200 blueberry plants and all of them have reddish leaves... can anyone tell me what this means? It did rain a lot the last few day.

Koko

High pH and/or low N availability (usually if over-watered or cool weather is lingering) are the general causes. The issue will stay the same or get worse if it's a too-high pH issue. It will eventually green up a good bit if it's a watering/weather issue. Low N can be a culprit on it's own, but if growth if overall plant growth is otherwise good it's usually not low N.

You see it a lot more in potted plants. It's a bit too easy to both over-water and under-water in pots...and the regimes for it change depending on whether it's cool/warm/hot.

It doesn't look like anything scary such as bacterial leaf scorch or phomopsis canker.

I am new to blueberry planting. We planted 10 plants last fall. I am also experiencing the red-brown leaves just as the picture shows above. I am deducting it to over - watering after reading the above material. However, we were also subjected to cold weather damage here (per the local nursery we purchased from). I have one bush in particular, that has nice green leaves at the base, bare for about 18" and then leaves at the top however, any blooms that come, quickly die off. Should I prune this down or should I just leave it be? Is it too hot for pruning? I also have another bush that has a nice green base but then the cane comes up 2-2.5ft and is completely bare.