Answer: You'll want to closely inspect the affected leaves. Look for brown spots or insect activity. Brown spots indicate a fungal infection; insect activity can also cause yellowing and browning leaves. If you find neither insects or fungal spores, the likely cause of inner browning of leaves is lack of water. Plants in containers can sometimes develop air pockets within the soil and rootmass. No matter how much water you apply, it simply drains quickly out the drainage holes. To overcome this condition, immerse the container in a larger container of water to thoroughly saturate the potting soil. Leave it for 10-15 minutes, or until no more air bubble rise to the surface. Then remove the pot from the container of water and allow to drain. Do this once every 2-3 weeks during the growing season and you'll control the problem.
Best wishes with your weigela!
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