Urban Horticultural Production

Soil Testing in Urban Horticulture

Urban horticulture is expanding as city residents transform vacant lots, backyards, and community gardens into spaces for fresh produce, herbs, and flowers. These gardens enhance community health, biodiversity, and sustainability. However, urban soil often faces issues from contamination, compaction, and poor management. Soil testing is a vital first step for urban growers, revealing key information about nutrients, pH, organic matter, and possible contaminants.

This guide provides a simple, step-by-step approach to soil testing, helping urban growers create healthy, productive, and safe gardens.

How to Collect a Soil Sample

Tools Needed

• Pair of gloves
• Clean plastic bucket
• Clean spade or shovel
• Clean travel or soil probe
• Ziplock bag or soil sample box (provided by testing lab)

Why Test Urban Soils?

Common concerns in urban soil include:

1. pH extremes (too acidic or too alkaline)
2. Compaction and poor drainage
3. Heavy metal contamination (lead, arsenic, cadmium)
4. Excess salt from past construction or irrigation
5. Nutrient imbalances (too much or too little nitrogen, phosphorus, potassium)

Soil testing helps you:

• Identify nutrient needs
• Determine pH adjustments
• Detect potential contamination
• Avoid unnecessary fertilizer use
• Reduce environmental harm
• Support long-term soil health
• Plan crop selection, amendments, and irrigation methods based on soil conditions

When and How Often to Test

When to Test: Ideally, test soil 3-6 months before planting, especially if amendments are needed.

How Often: At least every 2–3 years for ongoing gardens. Test annually if growing food intensively or applying compost/fertilizer regularly.

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Depth of Sample

Sampling Locations

Look for different environments in your field or garden and collect separate samples from areas that are mostly sunny versus those in deep shade, or dry areas versus wet areas.

*Do not sample compost areas, under the dripline of trees, or near sidewalks and driveways.

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