Black Plastic Pots

[FigMania]

In the summer heat, do black plastic nursery pots tend to get too hot.. like cooking the rootball? I was wondering if I should take these pots and spray paint them white or similar.. Like putting whitewash on the trunks of young trees to prevent sun scorch on the young wood. I ask because even here in the late winter on a sunny day my pots are really quite warm. IMWTK.

[cis4elk]

You are correct. You can paint them, I wrap and tape a layer of foil around mine.

[Evelynisgro]

Up north black is better, but if you get 95°+ I would paint them white.

[Brian M]

They are torture here in Fresno Ca. In fact, figs do better in the Summer with morning sun and afternoon shade.

[CliffH]

Here in Houston they will also very quickly bake, and kill, the roots of your plants. I almost lost about 4 trees to this last year, while I was just trying to find the time to plant them in the ground. I did paint almost all my pots last summer, after that. Many smaller pots packed together will also give them some shade. This year I have almost all my trees in white "bucket pots" or white grow-bags. But I have read that any color fiber grow-bags will stay cooler than plastic pots when the dirt is moist.

CliffH.

[Rewton]

One approach is to paint them white on one side but leave black on the other. When it is really hot you can rotate them so that the white side faces the sun.

[FigMania]

Good to know.. I have been wondering. Almost time to get out the extra latex paint.

[Bluemalibu]

Bill, the $2.50 orange buckets from Home Depot are hard to beat for the price, and they really reduce the temps that the plant's roots see. Their $4 white buckets likewise are a small price to pay for ensuring my expensive cultivars are safeguarded.

The tall tree pots are even more susceptible to the steamed veggie effect, due to the large surface area vs. the small damp soil content within. I've already addressed this issue, even though it's still only March, as it requires less than sixty seconds and five cents to effect the change:

[FigMania]

How do the Homer buckets hold up? I have a few white buckets that are not really the white ones.. more like translucent milk jug appearance.. They get sun rot pretty quickly and fracture.

[Bluemalibu]

How do the Homer buckets hold up? I have a few white buckets that are not really the white ones.. more like translucent milk jug appearance.. They get sun rot pretty quickly and fracture.

The white buckets have four years on them, and so far have shown no signs of degradation yet. The orange have shown cracking in maybe one in ten, in that same time frame.

[Fygmalion]

I agree with Doug... I have white 5 and 7 gallon and they hold up for a number of years which likely coincides with the need to trim the root balls anyway...

[FigMania]

Great news.. thanks guys

[BrooklynMatty]

What kind of paint would you guys recommend?

There is another alternative of using tyvek UV resistant fabric and cove the pots in this. Easier and safer for plants as I personally would need to spray plants while they are in the pot.

Also to note, that semi burying them has big advantages to keeping root temps down for black pots. I wrote a thread about it, lots of other benefits as well.

[FigMania]

I'm going to use leftover house paint.. interior latex is what I have. I don't care if it is 100% effective from weathering standpoint. It's cheap when you have leftover. It's the same paint I use on the trunks of new trees. I dilute it to a whitewash level and roll it on the fruit trees until the develop a denser bark. I'm guessing it will work ok for the pots. I like Blue's idea of paper for the tree pots.

[AscPete]

There have been several discussions regarding pot colors and root temperatures on the fig forums and I usually link this document and quote to the discussions...

http://krex.k-state.edu/dspace/bitstream/handle/2097/3298/JohnMarkham2010.pdf

After four months (June-October), plant variables were measured. Roots were separated into three sections: core (10.2 cm diam.), north, and south, rinsed of all media, dried and weighed. In the bean study, media temperatures at the sun-facing side averaged lowest in gloss and flat white (~36 oC) and greatest in the black control (50.3 oC). Accordingly, total root biomass at the sun-facing side was reduced by 63 to 71% in black compared to flat and gloss white containers. In heat-sensitive maples, media temperatures at the sun-facing side averaged up to 7.7 oC greater in black, black shade and green than in other treatments; temperatures in black shade may have been lower if shade cloth had covered the sun-facing sides of containers in addition to only the media surface. Media temperatures in the core averaged 3.5 to 3.8 oC greater in black than in flat and gloss white, resulting in up to 2.5 times greater below ground biomass and up to 2.3 times greater above ground biomass in flat and gloss white than in black pots...

At temperatures over 30 oC, root growth slows considerably (Johnson and Ingram, 1984). For many woody species root growth will stop completely at temperatures above 39 oC (Mathers, 2003). The roots of some woody species (e.g., Ilex crenata ‘Helleri’) die when exposed to temperatures of 51 oC for merely thirty minutes (Martin et al., 1989). Studies have revealed that temperatures inside nursery containers can rise much higher than 51oC, and commonly surpass 54 oC in the southern states (Ingram et al., 1989; Martin et al., 1989) (Mathers, 2000).

Note:
30 deg C = 86 deg F
39 deg C = 102 deg F
51 deg C = 124 deg F

White or Shaded pots seem best for sunny warm areas and IMO, an Exterior Latex paint can be used to not only reflect the radiant heat but also the damaging UV light that will degrade many plastics. Also paint rollers, those used to apply paint to interior walls are an efficient way of applying inexpensive exterior paint. Good Luck.

[FigMania]

Yep.. as mentioned.. I'll use diluted interior.. I'll just have to reapply more often. Thanks Pete for the research material.