Watch water arriving during rain
Observe the bed safely during or soon after a typical rainfall. Note runoff from paving, roof outlets, slopes and neighbouring surfaces. Mark where puddles first appear and photograph them with a fixed reference such as a path edge. A low corner receiving water from a large hard surface has a different problem from a whole bed that drains slowly. Do not begin by adding material to the planting holes before understanding this wider route.
Record how the bed changes afterward
Check the same locations at intervals after rain stops and note how long visible water remains. Compare a wet patch with a better-performing area nearby. Include recent weather, since a brief intense storm after dry conditions does not represent the same situation as weeks of saturation. Keep off very wet soil to avoid further compaction. A simple sketch with times and photographs is often enough to reveal whether the problem is local, seasonal or consistently spread across the whole bed.
Inspect the soil profile carefully
Where safe and practical, examine a small soil profile away from important roots and buried services. Look for compacted layers, abrupt changes in texture or water collecting at a particular depth. A basic infiltration comparison can provide clues, but results depend on method and starting moisture; one improvised hole does not diagnose an entire garden. Seek local guidance for a more formal drainage assessment if major changes are planned. Do not assume that filling a planting hole with gravel creates an outlet for water that has nowhere to go.
Choose the least complicated effective response
Possible responses include preventing unnecessary runoff, improving soil structure over time, relieving an identified compaction problem when conditions are suitable, using raised planting areas or choosing plants adapted to the site's moisture. Engineered drainage needs an appropriate lawful outlet and may require professional assessment. Record the specific cause you intend each change to address, then compare the bed after similar rainfall. This prevents expensive repeated amendments based only on the word clay. A successful remedy is shown by a workable root environment and healthier plants, not simply by how quickly water vanishes from one freshly dug test hole.
A little further reading
Match these general notes to your plant variety, climate and local conditions.
