I am setting up a sprinkler system (spot spitters) for my containers. One of the goals is to reduce the temperature of the growing mix in the containers. I can effectively supply water/nutrients to the root zone in several ways (e.g. lower volume/longer duration or higher volume/shorter duration) depending on the spitter I use. Is there evidence to suggest one is better than the other for reducing temperature?

Thanks in advance,
~james

As far as evidence pertaining to which approach will cool the potting mix better I don't have any ;) I would think high volume would do it better as it would have the water moving throughout the container faster and less opportunity for the water to be warmed at the surface, but the difference probably isn't great either way.

Al

Al, you bring up a good point. My initial thought was to set the timer a little later in the afternoon to speed up heat loss. In TX not only does it get hotter, but it stays hotter for a larger portion of the day. For example, tomorrow the weather forecast indicates it will reach 80F by 10am, 84F by 11am, peak at 86F from noon until 6pm, and not fall below 80F until 9pm. These temps are still pretty mild. Realistically, in a couple of weeks the first digit of those temps will be '9's, and it will stay like that into September.

Does my thought to give up control of the root zone temperature during the heat of the day and bring it back down quickly when it is possible to do so make sense? Any input is greatly appreciated.

~james

p.s. if it makes a difference, all of the containers in question contain deciduous fruit trees.

I know you have a lot of trees, but have you considered shading the containers? You could use the white fabric that the fine mesh outdoor furniture is made of. If you cut circles a little larger than the containers, then cut a slit to a center that was relieved to fit around the trunk, they will rest on top of the soil or container walls and shade the entire container while still allowing water and air permeability. When I get the gardens situated and can take a breath, I plan on doing this with many of my bonsai - especially those in dark pots & the material I have growing on in (black) nursery containers. I was touring the Frederik Meijer Gardens & Sculpture Park collection a couple of weeks ago & they are using this technique with noticeable success for their trees not accessible for public viewing.

BTW - nice to see you. You don't come around enough. ;o)

Al

Sorry, I have been so busy, I have not had much time to check in. My trees have also been neglected. Not so good while temps are approaching 100F. It is always good to come in and see old friends.

I understand high temps have an impact on root function. I guess the question is if the impact worsens as temperatures rise (e.g. is 100F worse than 90F?) Or is the impact on function the same at all temps above a given threshold?

lruett,

I use Air-Pots elevated off the ground. I grow off the ground due to the presence of RKN in my back yard and in Air-Pots to increase the interval between root pruning.

This is a pic of my set up from early 2008:

I can attach something (i.e. pink insulation board, aluminum flashing, etc.) to the side of the trays which face the sun. At this time of summer, the sun is high in the sky, which makes it difficult to effectively shade the container. Since I am setting up the sprinkler system, and can set it to water at any time during the day, this is a bit of a bonus.

~james

James,

Impressive set up. Very nice and organized unlike mine. Lol. Where did you get air pots? I use Rootmaker, Smart pots and Roottrapper (great for keeping mix cooler). I read somewhere that once it reaches 95*F, root growth or top growth (?) slows down. Of course pot in ground is best as I have smart pots filled with garden soil and trees are growing like weeds. I wish I had more space and better soil for that. My soil is all rocks...

James - there are white, uv-resistant poly slip-covers you could use for your trees' containers that help prevent heat build-up considerably in soils in containers exposed to the sun. They breathe and reflect light/shade the container. Would that help you?

Al

At this point it is a bit of a moot point. I have been traveling for the past five weeks, during which time I was planning and ordering components for the sprinkler system. Also during this time, the people who were suppose to water my trees did not. Between figs and pomegranate I lost about 120 trees. I only have seven left to worry about.

Since the winters here aren't so harsh, I'll rebuild in the fall.

As for the slip covers, I remember some slip covers being available from RootMaker. I'll look into those.

thank you for your input.

~james

Fare well, James.

Al

She didn't. The day I left her family was notified of a death in the extended family and left town immediately. Not her fault at all, but my plants didn't understand that.

My losses were nowhere near as extensive as yours though.

~james

For example: I really need to reduce the number of plants I tend so I have more time to devote to the really good bonsai. A lady that had attended a garden walk at my home a few years ago remembered that I did bonsai & showed up knocking at my door at noon Sat, wanting to buy a bonsai tree for her college-age daughter, who was with her. Wouldn't you think that out of a collection that size, that you wanted to reduce, that you could find at least one tree you'd be willing to sell off? NOPE. I ended up giving her a lollipop-shaped Eugenia that was left over from our club's last workshop in the name of promoting bonsai. I'm telling you - it's like selling your kids ..... so I really do feel your pain.

Al

Have you considered growing them in the ground using knitted bag or smart pots using topsoil? That's what I'm doing in a tiny section of my lawn and apparently they need much less water AND growing like weeds ( in a former plant bed that has been extensively ammended). Too bad, I can't do large numbers in the ground as my soil is not very ideal because I live on limestone rubbles and that means removing rocks that are in the way. If I ever started a tree farm, I would be using exclusively knitted bags and roottrapper bags to cut back on watering in hot weather...