Rain Garden Maintenance

To keep your rain garden healthy and thriving, follow the maintenance steps below.

Print a maintenance guide available in English, SpanishVietnamese, Traditional Chinese, and Cambodian.

Watch a video to learn how to weed and mulch your garden, in English, Spanish and Vietnamese.


Weeds can choke young plants and spread quickly. Pull weeds by hand or with a long- handled weed puller. Weed as necessary year-round, especially in late winter, spring, and early fall when the soil is still moist. Pull the entire weed–roots and all—so that it doesn’t immediately grow back. Never use herbicides/pesticides in your rain garden. Also, be sure to clean any sediment, debris, or trash from the inlets and outlets of your rain garden.

Need help identifying weeds in your rain garden? Check out the photos at the bottom of this page. If you need more help identifying a weed, the City of Portland’s Weed Identification Guide is a great resource.


Weeds to Remove:

weeds to remove 1

weeds to remove 2weeds to remove 3

If you need more help identifying a weed, the City of Portland’s Weed Identification Guide is a great resource.



Mulch (such as compost, leaves, and wood chips) prevents weeds, conserves water and protects roots. Check and maintain a mulch layer to a depth of 3 inches as necessary. The best mulch in a rain garden is arborist wood chips, available free from tree services. Look for any areas of exposed soil and cover them with mulch when needed. Be careful to avoid piling mulch up against plant stems.



Young plants need water to grow strong roots. Watering is important during the first two to three summers after your rain garden has been installed. In general, water when the weather is dry and warm, from May through September. Watering before 8am is best to reduce evaporation.

Be sure to water deeply, moistening the top 6-12 inches of soil. After watering, wait an hour, then dig down to see if the water has gone deep enough.

You can use a watering wand, oscillating sprinkler, or save time by laying out a soaker hose next to your plants and covering it with mulch. Learn more about how to water new plants and how to use a soaker hose.

Watering table



If you need to remove dead or dying plants, replace them in the fall. This will give the plants time to grow more roots before the dry season. More extensive roots help plants fight off disease, dry summers, and cold winters.

The following are plant suggestions and plans which may be useful if you need to replace a rain garden plant: