Recommended Free Tools
A rain garden is a planted depression that temporarily holds runoff from a roof or paved area while water soaks into the ground. A sound design starts by tracing exactly where the water comes from, then checking whether the proposed site can infiltrate it and safely handle overflow. Size, setbacks, and drainage-time guidance vary by location, so treat published figures as local examples and confirm requirements before digging.
1. Trace and measure the runoff that will reach the garden
Watch the property during or after rain. Identify which downspouts, driveway sections, patios, or other hard surfaces send water toward the proposed site. Measure only the area that actually drains to it. For a roof, count the roof plane or portion served by the downspout you plan to connect—not the entire roof by default.
Massachusetts Department of Environmental Protection guidance illustrates combining partial roof area with driveway or walkway area before estimating runoff. Its example converts a one-inch rainfall to feet and multiplies by the contributing area: 1,000 square feet produces 80 cubic feet of runoff from one inch of rain. This is a worked example, not a universal storm-design requirement; the publication year is not stated on the retrieved page. Massachusetts DEP rain garden guidance.
2. Choose a suitable site and test it before sizing
Look for a relatively level location that can receive runoff without sending it toward a building or a neighbor’s property. Avoid steep slopes, underground utilities, and places where seasonal groundwater or slow drainage would prevent infiltration. Contact the applicable utility-locate service before excavation, and check local codes or permit requirements.
The Tool Desk
Outbyte Driver Updater FREEScan for outdated or missing drivers - takes under a minuteDriver Scan →Outbyte PC Repair FREEClear out junk files and repair common Windows errorsFree Scan →#1 Best Overall
- COVERAGE: 20,000 seeds of creeping thyme (Thymus Serpyllum) provide extensive ground coverage for gardens, pathways, and landscaping areas
- PERENNIAL GROWTH: Hardy flowering plant returns year after year, creating a dense, low-growing mat of fragrant foliage and delicate purple blooms
- VERSATILE PLANTING: Ideal for rock gardens, between stepping stones, lawn alternative, or as an attractive border plant that helps suppress weeds
- GROWING SPECIFICATIONS: Thrives in full sun to partial shade, reaches 2-4 inches in height, and spreads up to 18 inches per plant
Check setbacks and slope guidance locally
Distances and slope limits are recommendations, not universal rules. Massachusetts DEP recommends at least 10 feet from foundations and 50 feet from wells or septic systems. Virginia Cooperative Extension at Virginia Tech also advises at least 10 feet from building foundations and avoiding septic fields and high water tables. Confirm local requirements and site conditions rather than applying these figures automatically. Massachusetts DEP; Virginia Cooperative Extension.
Portland’s residential guidance says rain gardens are unsuitable on slopes over 10 percent. That is Portland-specific guidance, not a general limit for every location. City of Portland rain garden guidance.
Rank #2
- AAS WINNER & OUTSTANDING QUALITY: Verbena Moss is an All-America Selections winner, recognized for its exceptional decorative qualities and vintage appeal. This sustainability champion features a stunning color range, making it a must-have for any premium garden collection.
- 6,000 PREMIUM AMERICAN SEEDS: Get 6,000 fresh, clean, and Non-GMO seeds with no fillers. These seeds are effective and easy to plant, ensuring vigorous, compact growth of multicolored perennial ground cover that spreads beautifully across your landscape.
- COLORFUL LONG-BLOOMING GROUND COVER: Elevate your garden aesthetics with this exquisite floral mix. These beautifully branched, compact plants feature tiny complex flowers grouped into large, rounded umbel-shaped clusters, creating a living bouquet effect.
- VALUABLE COLOR ASSET: More than just a flower, this variety is a master of color and impact. It boasts an impressive range of expressive shades—white, cream, pink, red, lavender, lilac, and purple—set against delicate, fern-like foliage for a picturesque tapestry.
- CONTINUOUS FLORAL DISPLAY: Ultra-decorative, lacy, and airy green foliage with a fine feathery texture forms a soft cushion for clusters of star-shaped, saturated flowers. This contrasting palette transforms ordinary gardens into extraordinary landscapes with long-lasting blooms.
Test infiltration and groundwater
Use the local extension or stormwater authority’s method to assess how quickly water drains from a test hole and whether seasonal groundwater is too close to the surface. Massachusetts guidance cautions that a garden may be unsuitable if water remains in the test hole or groundwater is too high. Portland recommends an infiltration test and warns against compacted native soil. A site that drains poorly may need a different stormwater approach rather than a deeper or larger rain garden.
3. Size the garden for both inflow and soil conditions
There is no single sizing formula that applies everywhere. The required footprint depends on contributing area, runoff volume, allowable ponding depth, and the native soil’s infiltration rate. Use a locally accepted method after checking the site, and treat rules of thumb as starting points rather than design standards.
Quick wins for a faster PC:
Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →Repair Windows errors before they cause bigger problemsFix Now →Rank #3
- High Germination Ease: Sow aubrieta cascade purple aubrieta deltoidea seeds in 60–65°F soil. Aubrieta rockcress sprouts in 10–14 days, ideal as flower seeds for airy borders, walls, rock gardens.
- Impressive Heat Tolerance: These purple flowers plants flourish as full sun heat tolerant plants, thanks they are drought resistant flower seeds. Great ground cover seeds for any outdoor spaces.
- Excellent for Slopes: aubrieta seeds-perennial bloom as flowering ground cover. A top pick among best landscaping plants for full sun, creating creeping flowers that resist erosion & reach 6" height.
- Year-Round Charm: aubrieta plants act as drought resistant plants and fast growing ground cover. Sow rock cress seeds perennial from flower seeds packets for a lush display in USDA zones 3-10.
- Dynamic Landscape: aubrieta seeds doubles as perennials deer resistant & perfect for erosion control plants. Rockcress seeds for planting is low maintenance ground cover & can thrive in almost no soil
| Guidance source | Published sizing figure | How to interpret it |
|---|---|---|
| Massachusetts Department of Environmental Protection | About one-eighth to one-third of the drainage area | General rule of thumb; soil and slope affect the actual size. Publication year not stated on the retrieved page. |
| Virginia Cooperative Extension, Virginia Tech | Drainage area divided by 20 | Presented as a minimum square-footage rule of thumb; publication date shown as 2024. |
| Oregon State University Extension | No single ratio stated | Identifies runoff volume, allowable ponding depth, and native-soil infiltration rate as governing factors. |
The differing figures are not competing universal standards. Local soil, rainfall criteria, and design requirements determine which method is appropriate. Use Massachusetts DEP’s sizing examples, Virginia Cooperative Extension’s guidance, or Oregon State University Extension’s rain garden guide for their respective contexts.
4. Shape the garden and plan where overflow will go
The garden can be shaped to fit the yard, provided its effective ponding area meets the chosen design method. Protect the inlet from erosion, avoid compacting the soil intended to absorb water, and include a stable overflow route for storms that exceed the garden’s storage or infiltration capacity.
Rank #4
- SPOTTED JOE PYE WEED WILDFLOWER SEEDS: Open-pollinated Spotted Joe Pye Weed (Eutrochium maculatum) seeds for growing a beautiful North American native plant adapted to USDA zones 3-8
- POLLINATOR MAGNET: Beautiful Joe Pye Weed supports native bees, butterflies, and beneficial insects; moisture-loving perennial creates essential habitat and provides spectacular late-season blooms
- STUNNING 4-8-FOOT DUSTY ROSE-PURPLE BLOOMS from July through September; thrives in full sun to partial shade with natural deer resistance; perfect for rain gardens, pond edges, wet meadows, and butterfly gardens; self-seeds for expanding wildflower displays
- DETAILED GROWING INFORMATION: Paper seed packets include clear planting instructions, germination tips, and seed-saving info, great for beginner or experienced gardeners growing vegetables, herbs, flowers, or native plants
- FAMILY OWNED USA SMALL BUSINESS – Heirloom non-GMO seeds from Survival Garden Seeds, a trusted American brand; always open-pollinated, untreated, and quality tested for garden success
Possible approaches include one garden, multiple connected gardens, or a swale or other suitable route for excess runoff. Choose among them based on available space, site infiltration, the runoff each can safely handle, maintenance needs, and a safe destination for overflow. Virginia Tech and Oregon State Extension both advise planning for excess runoff. A rain garden has finite capacity; do not assume it will capture every storm or prevent flooding. Virginia Cooperative Extension; Oregon State University Extension.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.5. Select plants for the basin and the drier edges
Choose plants suited to your local climate and divide the planting by moisture conditions. The basin may stay wet for a time after rain, while the outer banks generally experience drier conditions. Virginia Tech and Illinois Extension describe selecting plants for these distinct zones. Rather than relying on a universal species list, use a local native-plant list or ask a regional extension service or nursery for plants suited to your site. Virginia Cooperative Extension; Illinois Extension.
Best Value
- Moisture-Loving Plant: Thrives in moist soils, making it ideal for rain gardens, wetland areas, and pond edges.
- Pollinator Host Plant: Attracts bees, butterflies, and other pollinators with its unique turtle-head shaped flowers.
- Native Perennial: Supports local ecosystems by providing food and habitat for native wildlife.
- Low Maintenance: Once established, White Turtlehead requires minimal care and is easy to grow.
- Wetland & Rain Garden Favorite: Perfect for creating natural wetland or rain garden environments.
6. Inspect after storms and keep the system working
Check the inlet, overflow, planted basin, and berm for sediment buildup, erosion, or damage. Remove excess sediment and repair damaged vegetation or berms so water can enter and leave by the intended routes. Massachusetts DEP recommends inspection every three to six months and after large storms.
Use local drainage guidance when judging how long water should remain. Portland says its residential gardens should drain within 24 hours; Massachusetts guidance advises avoiding standing water beyond 24–36 hours. These are source-specific recommendations, not a single universal deadline. Persistent standing water is a reason to reassess infiltration and site conditions. City of Portland; Massachusetts DEP.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
