If they don't appear to be blocked, you may need to change out the compost mix because it can decay and become soggy and waterlogged over time. [substeps] Also check your planter after rain.
[header] How to maintain a planter [title] Check that your planter is draining freely during each watering. [step] If your planter doesn't drain freely after several waterings, the drainage may be blocked. Look underneath the planter and check the drainage holes.