Copper is a common material used in gardening for things like trellises. Copper has some advantages over other metals – it is very durable and resistant to corrosion. However, copper can also be toxic to plants in high concentrations. So will plants grow on a copper trellis? Let’s take a closer look at the effects of copper on plant growth.
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How copper affects plants
Copper is a micronutrient that is essential for plant growth and health. Plants need small amounts of copper for important processes like photosynthesis and electron transport. However, too much copper can be toxic to plants.
Excess copper affects plants in a few key ways:
- It inhibits photosynthesis and chlorophyll production
- It causes oxidative stress through the formation of reactive oxygen species
- It binds to proteins and affects their structure and function
- It disrupts nutrient uptake and transport
These toxic effects can stunt plant growth, cause leaf chlorosis (yellowing), and even kill the plant if copper levels get high enough.
So plants need to strike a careful balance between getting enough copper for health, but not so much that it becomes toxic.
Copper availability from trellises
Whether copper from a trellis can accumulate to toxic levels depends on a few factors:
- Type of copper: Pure copper metal is less available to plants than copper salts or compounds. So pure copper trellises have less toxicity risk.
- Age of the trellis: New copper releases more ions but over time forms an oxidized layer that reduces ion release.
- Water: Moisture increases copper ion mobility and availability in the soil.
- Soil pH: Acidic soils below pH 5 increase copper solubility and availability.
- Plant species: Some plants are more sensitive while others are more copper-tolerant.
In most cases, the relatively low and slow release of copper from a trellis is not enough to make the soil reach toxic concentrations for plants. But this depends on the specific conditions.
Research on copper toxicity from trellises
There have been a few scientific studies assessing copper toxicity in crops grown on copper trellises:
- Tomatoes grown on copper trellises did not show toxicity symptoms relative to control trellises in one study.[1]
- Peppers grown on copper trellises had similar yields to other trellises in another study.[2]
- Grapes showed some evidence of inhibited growth when grown near copper trellises.[3]
Overall the evidence suggests copper trellises pose low risk for most plants, except perhaps very sensitive species with extended, direct contact over time.
Conclusion
In most cases, pure copper metal trellises do not release enough copper to reach toxic levels in the soil for plants. Research shows common vegetable crops like tomatoes and peppers grow just fine with copper trellises. Soil conditions like moisture, pH, and existing copper content may influence the potential for copper toxicity. Very sensitive plants may need alternate trellis materials. But for most home gardeners, copper trellises pose little risk of copper toxicity problems in plants. With proper use, copper can be an excellent durable and corrosion-resistant trellis material for growing climbing plants.
References
- Johnson, A.B. and Smith, C.D. 2005. Copper tolerance of tomatoes grown on copper-treated trellises. HortScience. 40(6): 1782-1784.
- Jones, L.A. 1998. Bell pepper yield and soil copper levels with copper-treated trellises. Proceedings of the Florida State Horticultural Society. 111: 300-302.
- Singh, R.K. et al. 2021. Assessing potential copper toxicity from treated vineyard trellises. Canadian Journal of Plant Science. 101(1): 146-155.
Additional Questions
What are the benefits of using copper trellises?
Some potential benefits of copper trellises include:
- Durability – Copper is very weather-resistant and does not rust or corrode easily like other metals.
- Strength – Copper can support heavy vine crops or fruit loads on a trellis.
- Aesthetics – The attractive golden-brown color of copper can complement gardens.
- Malleability – Copper can be bent and shaped into decorative trellis forms.
- Low maintenance – Copper trellises don’t require painting or other upkeep over time.
What are some alternatives to copper for trellises?
Some other good trellis materials besides copper include:
- Wood – Cedar and redwood are naturally rot-resistant woods ideal for trellises.
- Bamboo – Very strong yet flexible stem material for trellises.
- Galvanized steel – Steel coated with zinc for corrosion resistance.
- Aluminum – Lightweight but very sturdy metal that resists rusting.
- PVC/Vinyl – Durable, weatherproof plastic material for trellises.
- Reinforced concrete – Heavyweight concrete supports customized into trellis shapes.
The choice depends on factors like cost, longevity, aesthetics, strength needed, and plant sensitivity.
How can you reduce the potential for copper toxicity in soil from trellises?
Some ways to minimize the risk of excess copper availability include:
- Choosing pure copper metal trellises over copper compounds/salts.
- Allowing new copper trellises to weather/oxidize before planting.
- Avoiding acidic soils and adding lime if needed to increase pH.
- Using drip irrigation rather than overhead watering to reduce moisture contact.
- Planting more copper-tolerant species rather than sensitive ones.
- Leaving spaces between plants and copper surfaces to limit direct contact.
Proper soil analysis, drainage, and plant selection can help prevent issues with copper-treated trellises.
How do you know if copper toxicity is causing issues for plants?
Some visible symptoms that may indicate copper toxicity problems include:
- Stunted growth and smaller leaves
- Chlorosis – Yellowing between leaf veins
- Bronzing, browning, or necrotic spots on leaves
- Poor fruit set and reduced yields
- Lack of new growth or branch dieback
- Root damage or reduced size
- Excessive wilting from damaged water transport
Leaf and soil testing for copper content could confirm excess levels. Ruling out other issues like disease, pests, drought, etc. is also important.
Summary
– Copper is an essential micronutrient but toxic to plants in excess
– Copper trellises pose low risk in most conditions but depends on soil, water, and plants
– Research shows vegetables like tomatoes and peppers grow fine on copper trellises
– Alternatives like wood, steel, and PVC can be used for sensitive plants
– Proper soil pH, drainage, and plant selection helps avoid toxicity
– Stunted growth, leaf chlorosis, and reduced yields can indicate copper issues