My recent video on our new conduit/remesh trellises was very short but prompted a lot of questions.
Is rust harmful to the soil or plants,
will the metal scorch plants,
what was your total cost, and how long will the trellises last?
and how long will the trellises last?
Today I'll do my best to answer these questions.
Let's start by talking about rust.
The rust that forms on steel remesh and rebar is iron oxide,
which is naturally occurring in soil and is responsible for the red or yellow color of some soils.
Iron is an essential plant nutrient that plays an important role in the production of chlorophyll.
Though it’s possible to have too much iron in the soil,
iron toxicity is not very common
and iron oxides are not readily available to plants.
For these reasons, I’m not concerned about the rust having a negative impact on the soil.
but if some gets on my tomatoes, I’ll rinse them off before eating them to avoid the unintended iron supplement.
If you’re still concerned about the rust, you can use galvanized cattle panels instead.
Like cattle panels, the electrical conduit we use for our trellis frames is made from galvanized steel,
which prompted questions about its safety.
Galvanized steel is treated with zinc, which is released during corrosion along with iron oxide.
Like iron, zinc is an essential nutrient,
and according to an article in Rodale’s OrganicLife Magazine:
“Due to zinc’s limited bioavailability in soil,
there is little chance of ingesting too much zinc through plants grown in proximity to galvanized metal."
Jeff Lowenfels, author of Teaming with Microbes, is also quoted in the article, saying:
“I am willing to let the arbuscular mycorrhizal fungi take up excess zinc,
feed the plants what they need, and hold the rest.”
So, I’m not worried that the trellises will add dangerous levels of the essential nutrients iron and zinc to the soil.
Some suggested painting the trellises to to contain the rust,
but I’d rather have iron and zinc in the soil than paint residues.
The next question is whether the trellises will get hot enough to scorch plants.
We’ve used conduit trellis frames for years without incident,
but this is the first time we’ve used remesh instead of nylon or twine netting.
The first thing I did to begin testing this out is to touch the remesh and conduit at various times of the day
to get a sense of the temperature.
Both were almost always cool to the touch.
The only time they felt a little warm was at midday on sunny days,
but they never felt hot.
My guess is that, because the trellises have contact with the soil
to a depth of nearly two feet,
that the soil helps keep them cool.
Not satisfied with this approach,
I set up an indoor/outdoor thermometer
to record both the temperature of the trellis
and the air right next to the trellis.
Ideally, I wish I had two external sensors -
one for the conduit and one for the remesh.
But having only one, I wedged it between the remesh and conduit,
thinking this would give me the average temperature of the two.
I hung the thermometer from a coat hanger as shown here, and began tracking temperatures.
Every single time I checked the temperatures during the day,
the trellis temperature was significantly lower than the air temperature,
even on warm sunny days at midday.
Here’s a look at a number of those readings.
The first reading in each set of 2 is the temp of the air.
The second is that of the trellis.
The only time the trellis was warmer was at night.
This could mean that the soil is helping to moderate the temperature of the trellises.
This could prove to be a significant advantage if this trend continues.
For example, the trellises may cool plants on hot days
and provide warmth when there's a danger of frost.
In addition to taking random readings over the course of several days,
I started recording the max and min temps, which are tracked by the thermometer.
As you can see, over the course of a few days,
the air had higher max readings.
Though it’s hard to tell from the chart, the trellis had slightly warmer min temps.
Given what I’ve observed so far, I’m very confident that the trellises won’t scorch plants,
at least at this time of year in zone 5.
Going forward, I’ll track min and max temps on a weekly basis to see if this
changes as we move into the summer months,
but I'm confident the trellises will actually remain cooler.
Not only will the soil continue to moderate their temperatures,
but as plants grow to cover the trellises
they'll provide shade and a cooling effect
I'm very curious to see what happens,
and I'll let you know as soon as I have the data.
A number of you also asked about the cost of the trellises.
Here's a breakdown of all the materials and their costs.
We were lucky enough to have all of the materials on hand except for the remesh,
so our cost was only $7.25 per trellis.
If you buy all the materials, it’ll cost you $27.91 for the first trellis,
but you’ll have some materials left over to build the next one.
Because these trellises are bit pricey,
I recommend making them only if you want to grow some heavy crops
like winter squash, watermelons, are densely planted indeterminate tomatoes.
Finally, a number of you asked how long the trellises will last.
I know for certain that the conduit frames last a very long time.
Many of ours are well over a decade old and are in perfect condition.
But this is the first time we've used the remesh.
According to an article on High Mowing Organic Seeds website,
remesh can last 20 years and still be in great shape.
But if you're still concerned about longevity,
you can always try galvanzied steel cattle panels instead.
This will last longer.
I hope this video answered some of your questions.
If you’ve used remesh trellises long enough to know how long they last,
please leave a comment below to let us all know.
Well, that's all for now.
Thank you very much for watching,
and until next time remember
you can change the world one yard at a time.
You've lost your mind.