Gardening in urban soils

I’ve been doing more research into edible gardens and soil contamination lately, and I thought I would share my findings here. As my family prepares to move onto a new city lot with old homes and unknown previous uses (e.g. there was rumor of the property having been rented to a fellow with a roofing company once), we’ve been thinking more carefully about where to place raised planter beds, play areas and fruit trees.

It seems that most plants don’t take up contaminants, but the greatest risk is direct contact with the soil. To find out what’s in your soil, do a soil test with the U. Mass Soil Testing Laboratory ( which offers a standard soil test for home gardeners including pH, nutrients, and extractable metals for only $10. They will send your results with recommended actions for various crops.

If needed, import new soil to your garden (from a reputable source like Cedar Grove) and cover pathways with wood chips, new soil/gravel or pavers. Then grow your garden and simply wash your hands and homegrown produce before eating.

Here are some more basic guidelines adapted from the US EPA (2011):

-Build your garden away from existing roads and railways, or build a hedge or fence to reduce windblown contamination from mobile sources and busy streets.

-Cover existing soil and walkways with mulch, landscape fabric, stones, or bricks.

-Use mulch in your garden beds to reduce dust and soil splash, reduce weed establishment, regulate soil temperature and moisture, and add organic matter.

-Use soil amendments to maintain neutral pH, add organic matter, and improve soil structure.

-Add topsoil or clean fill from certified soil sources. **Cedar Grove is certified organic, and tests regularly for heavy metals.

-Build raised beds or container gardens. Raised beds can be made by simply mounding soil into windrows or by building containers. Sided beds can be made from hemlock/fir wood, synthetic wood, stone, concrete block, brick, or naturally rot-resistant woods such as cedar and juniper.

-Your state or local city agency may recommend using a water-permeable fabric cover or geotextile as the bottom layer of your raised beds to further reduce exposure to soils of concern.

-Practice good habits:
Wear gloves, and wash hands after gardening and before eating.
Take care not to track dirt from the garden into the house.
Wash produce before storing or eating, and teach kids to do so, too.
Peel root crops, and remove outer leaves of leafy vegetables.

Published by HAZEL Landscapes & Edibles

We are two friends in Seattle, each armed with Master's degree in Landscape Architecture, years of farming and gardening experience, fine culinary tastes and creative streaks. Our designs, installations and maintenance programs reflect our dedication to good eating, beautiful living & play spaces, native plants, water-wise gardening and sustainable urban landscaping.

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