Troubleshooting Rain Garden Issues is all part of the Rain Gardeners service!
There are a few signs your may notice that show something is wrong and if your first action is to drop us a line, read no further! Consider the problem solved.
If you're curious about what may be causing pooling of water, runoff, dying plants or more, here's a list of common problems.
| Symptom | Possible Problems | Solution |
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Stormwater run off is bypassing the rain garden |
Local earthworks increasing sediment load to rain garden, blocking rain garden outlets, or raising the surface level of garden. |
• Check surface of the rain garden is below the surrounding area. • Remove any sediments and debris from inflow areas and from the surface of the rain garden. • Protect rain garden from future construction sediments. |
| Rubbish and other debris blocking the inflow points to the rain garden. |
• Regularly remove rubbish, leaves, and any other debris from inflow points.
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Rain garden is ponding for longer than 24 hours.
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Incorrect blend of soil mix.
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• Replace soil mix with the correct rain garden soil mix. • Do Ribbon test or percolation test to test soil mix is free draining |
| The soil within the garden compacted during construction or other activities. |
• Loosen the top 500mm soil by tilling or forking. • Discourage vehicle, pedestrian, and bicycle access to the rain garden. |
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| Layer of fine sediment settled on the garden surface. |
• Remove fine sediment layer and turn over the top layer of rain garden soil mix. • Protect rain garden from surrounding sediment run off. |
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Stormwater and/or mulch flowing off the rain garden.
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Rain garden filled with too much mulch or soil. | • Remove excess mulch or soil so that surface of ponding area is approximately 200-300mm below the surrounding hard surfaces and overflow. |
| Overflows or discharge pipes clogged with sediments or debris. |
• Clear overflow and discharge pipes.
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Planting or rain garden soil mix clogged.
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• It may be necessary to remove some of the rain garden soil mix and replace with fresh rain garden soil mix. | |
| Sulphur smell coming from the rain garden. | Plants and soils lacking oxygen. Organic material rotting in the garden. |
• Inspect rain garden after rain event to check garden drains within 12 to 24 hours.
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| The underdrain is clogged, and water is not properly draining out of the garden. | ||
| Erosion and gouging occurring within the rain garden |
Kerbs and other hard structures channelling stormwater flow. (Rain gardens require an even sheet flow of water to operate effectively.) Inflow points are too concentrated.
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• Create openings in the kerb to increase number and width of run off points, or replace kerbing with a different design (e.g., kerbing slightly raised off the ground). • Increase kerb opening size by cutting kerbs or replacing with different design. • If this is not possible install riprap (i.e. stones set into concrete) at the inflow point to spread flow and reduce erosion. |
| Plants are stressed or dying. Symptoms may include yellowing of leaves, unseasonal leaf fall, wilting. | Plant varieties selected for rain garden are unsuitable for the location and/or extreme wet/dry conditions. |
• Select plants appropriate for the location (e.g. full shade, partial shade, full sun, etc.). • Due to their hardy nature, native plants are recommended |
| Ponding or excessively long periods of flooding cause plants to become stressed and die. |
• Inspect rain garden after rain event to check garden drains within 12 to 24 hours. • See above solutions for rain garden ponding.
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| The plants poisoned by run-off from a hazardous spill (fuel, paint, oil, etc) Pollutants accumulated in the rain garden reached a toxic level for plan. |
• Check soil and mulch for evidence of heavily polluted run off (e.g. rainbow slick, coloured mulch, etc). • If contamination is extensive, clean out rain garden soil mix and replace fresh soil and new plants. • See construction guide for instructions. |
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| The plants dehydrated from extended dry conditions. |
• Newly established plants need watering. • Check soil moisture content and water plants if dry. • Establishing plants need watering in dry weather conditions. |
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| Plants stressed due to attack by plant pests or diseases. Pests may include insects or animals. |
• Check for leaf damage or pests and consult gardening manuals or a garden centre for the best treatment. • Stressed plants need replacing with healthy variety or pest-resistant species. |
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Rain garden soil mix compacted.
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• Loosen the top 500mm of soil by tilling or forking. • Do not allow vehicle, pedestrian, and bicycle access to the rain garden.
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