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Do Metal Garden Beds Heat Up More Than Wooden Beds?

Last year, I needed to replace some wooden garden beds that were falling apart. Earlier that year, I added one Garden In Minutes metal raised bed to my garden. I love the durability and 17″ (43cm) depth, and it’s a perfect fit with my watering grids.

However, given my location in a region with hot summers, I was uncertain about the practicality of replacing wooden beds with metal ones. Questions like “Are metal beds too hot for Arizona?” and “Do metal garden beds heat up more than wooden beds?” loomed large. I wanted to answer these questions before adding more metal beds to the garden. 

Do metal beds heat up more than wooden garden beds? See the temperature readings from four weeks of testing and make an informed decision.

Testing to see if metal garden beds heat up more than wooden beds

For the test, I took soil temperature readings from my metal Garden In Minutes bed and cedar garden beds for about four weeks. 

Note: The Garden In Minutes metal bed is made of Aluzinc Magnesium coated steel. This type of steel is less reflective than standard galvanized or Aluzinc garden beds. (Other metal garden beds may perform differently.)

Are metal beds too hot?  See the temperature readings from four weeks of testing and make an informed decision.

Soil Temperature Readings

DateTimeMetal
Middle
of Bed
Metal
Near
Edge
Cedar
Middle
of Bed
Cedar
Near
Edge
9/45pm70°F /
21°C
74°F /
23°C
70°F /
21°C
73°F /
22.7°C
9/86pm69°F /
20.5°C
72°F /
22°C
70°F /
21°C
72°F /
22°C
9/176pm 64°F /
17.7°C
69°F /
20.5°C
65°F /
18°C
71°F /
21.6°C
9/195pm65°F /
18°C
69°F /
20.5°C
65°F /
18°C
68°F /
20°C
9/265pm64°F /
17.7°C
68°F /
20°C
64°F /
17.7°C
67°F /
19.4°C
Metal vs. Wood Temperature Testing, September 2023

Results of testing to see if metal garden beds heat up more than wooden beds

Surprisingly, the temperature difference was not as significant as I thought it might be. The outer inch of the metal beds was usually (but not always) hotter by a degree or two. However, the bed’s interior was similar for both beds. 

Do metal beds heat up more than wooden garden beds? See the temperature readings from four weeks of testing and make an informed decision.
Mulching plays a crucial role in soil temperature

Incidentally, when taking additional measurements, I discovered that sun exposure, mulch, shade, and watering made a bigger difference than the bed type.

For instance, beds in direct sunlight on the western side of the garden heated up more than those on the eastern side. I also found that the soil temperature in beds with more mulch was lower than in those with less. Recently watered beds were cooler than if it had been a couple of days since watering. I didn’t record these measurements, but I plan to take additional readings next summer to document more soil temperature findings. 


Do metal beds get too hot? My conclusion:

Do metal beds heat up more than wooden garden beds? See the temperature readings from four weeks of testing and make an informed decision.

After the test, I concluded that the benefits of the metal beds outweigh the modest heat gain on the outer edge of the bed.

  1. Durability: Metal garden beds are typically more durable than their wooden counterparts. They resist rot and insect damage.
  2. Ease of Maintenance: Metal garden beds are easy to clean and maintain. Metal does not absorb moisture or bacteria, which reduces the risk of disease in your plants.
  3. Longevity: Galvanized metal is much more weather-resistant than wood.
Are metal beds too hot?

After conducting this test to see if metal beds were too hot for Arizona, I decided to use metal beds. I replaced three wooden garden beds with metal ones from Garden In Minutes.

Choosing the right raised bed can be tricky, but consider Garden in Minutes’ metal beds. Their durability, longevity, and ease of maintenance make them an outstanding choice. Even in hot climates, these beds stay cool enough for your plants.


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Rho

Thursday 11th of January 2024

Any readings taken for real months of June and July? Everyone who plays outdoor sports in the valley knows that really hot times are between 2pm and 4pm. Evening Temps are not peak heat hours. Were both types on the same sun exposure? It makes a difference when take temp reading at edge to be western or eastern exposure. Where are the error bars to your reading? The differences are so negligible to suggest that the instrument you use has +- errors Would love to see a better experimental design to answer the question.

Angela Judd

Thursday 11th of January 2024

All very good questions. The beds were the same sun exposure. Same beds, same spots for readings each time. You're right earlier in the day would have been better. This was to help me decide if I should add more of this type of bed or not. The results I saw were enough to convince me. I'm sharing what I learned here.

Patricia Smith

Thursday 11th of January 2024

Thank you I’m just contemplating buying some metal beds and I had that same question.

Angela Judd

Thursday 11th of January 2024

You're welcome. Glad it was helpful.