December 29, 2016

Good morning, How surprising after this last bit of “chilly” weather to find a tomato seedling in one of my temporary greenhouses. This was observed after a 17 degree morning. They are about 3 inches tall. This is one of the beds that is covered with Agribon 70, the heavy stuff. These plants do not look leggy or yellowing, two signs of not enough light.

On the other hand where I have used 3 layers of 19, I am seeing some signs of legginess. These beds have lettuce and beets, two crops that I would think would not have a problem with reduced light.

I have not figured out the light matrix under the fabric with greenhouse film.

A few years back I had the opportunity to use a light meter during winter under both the 70 and the 19. I did readings with both 1 layer of each and 2 layers each and the light reduction was a calculated reduction by reducing the amount of light by the number of layers. The agribon number is the indication of how much light is reduced with each layer. So with the 19 roughly 80% of the light gets through where as with the 70 only 30% gets through. On a sunny winter day when I took the my readings the direct sun was 10,000 lumins and under the fabric the 19 was about 7900 lumins and the 70 read around 3300. Pretty close to spot on.

These reading were made before I thought about the temporary greenhouses. There does seem to be something different about the light with greenhouse film under a single layer of 70 and 3 layers of 19. It would be interesting to take a reading under both of these configurations. The light seems to get “distracted” under the three layers. This is a little confusing because the temperature under 3 layers of 19 is a few degrees warmer than under the single layer of 70. These are some puzzling things.

This observation of a tomato germinating and growing under the greenhouse gives me some new thoughts about using 70

I have thought that the reason greens do so well is because the greens have larger leaves. I have felt this is due to most greens are from the higher latitudes where there is less light. The larger leaves help these plants collect more solar radiation. Where as Tomatoes and the other Solanaceae varieties are more tropical in nature. With more solar radiation the leaves tend to be smaller.

I have always thought that the 70 would not work as a permanent cover for these plants. This observation gives me pause.

I have been extensively using fabric for many years now and it still surprises me. I am going to use 70 on one of my tomato beds and just see what happens.

Being able to use the 70 on all of my beds would be more expensive but the 70 last about 3 times as long as the 19.

Some advantages would be that I would not have to make a mad dash to cover with a forecast of either hail or an impending cold spell. I also would not need to make sure that there are enough rocks on the fabric to anchor the fabric before a wind storm.

There is only one family of veggies that I remove the covers for and this is the cucurbits. These plants have to be pollinated by insects and must be uncovered for this purpose. They could easily be started under 70.

One of the observations that I made when I crawled underneath the covers, I noticed that the fabric acts like a prism and the light is reflected all around underneath the cover. The light meter reading was the same if it was under a plant or not. I feel the light is superior under the fabric. It also is an indication that we have more light than what plants need to grow.

This all plays into the fact as you take a walk across our desert landscape, where some shrub allows for shade. As this plant has been able to grow and increases in size, the soil is cooler under this shrub. Because of this cooling many other plants find an environment that they can germinate and grow also. These “mother” shrubs have become to be called nurse plants because they have created a much less harsh micro climate around their base, Much of which the fabric does.

I have said that I could garden with out fabric but with it, there is a much more level playing field.

I hope to be listing greens soon. There is a steady increase of productivity. I hate to list something and immediately say I am sold out. Please ask about availability.

Presently there are turnips, and sweets in abundance.