Well it depends who is doing the forecasting and who they’re forecasting for. But your point stands about microclimates. I guess I just expected you to keep more of a breeze there in a coastal town even a bit away from the shore, but I suppose with lighter flow it wouldn’t take much radiational cooling to drop you a few extra degrees from the wide open airports…especially with trees around you to help knock down the wind. I lived in Naples briefly near APF airport and there was noticeably more “dead air” a few miles inland versus the coast.
Anyway good luck and hopefully those 80s winters stay away from you.
i am surprised too since i thought the woods here would give me some sort of microclimate and i’m not that far from the beach. i compare the weather channel, accuweather and weather underground lows (recent, within 24 hours) to my thermometer lows (also within the past 24 hours), and they’ve varied by anywhere from 1 degree to 7 degrees. 7 degrees makes a big difference to tropicals! not sure what you mean by ‘who they’re forecasting for’? i love Naples but it has gotten crowded the past several years.
I am also surprised to see that big of difference in such a flat, generally low-lying coastal area, but microclimates can be surprising.
My own microclimate creates a similar problem. I’m less than a mile from the beach, but I’m in a bowl-shaped depression on a plateau about 300 ft above sea level. On overcast or windy nights, Google’s GPS-based temperature “guess” (i.e., what my Android phone says is the current temperature in my location based on nearby public weather stations) is spot-on. But on clear, calm nights (often the case during our worst freezes), my outdoor sensor reads about 5-7 °F colder than the weather app’s guess, because the cold air pools in my neighborhood.
Yeah 7F is a big difference. We see large differences over short distances up here as well…usually under clear calm skies on the back side of a surface high pressure system. The valleys radiate and bottom out while the higher elevations stayed mixed and even start seeing warm air advection from the SW. it can be -30° in the valley bottom and 0° on the hill tops.
By “who they’re forecasting for” I just mean the meteorologist’s forecast and the site or region the forecast is for. Some of the TV guys will give the forecast numbers for the big city airport official station because those are the conditions and highs/lows they show on air. The NWS puts out many different forecasts. There’s graphical forecasts that have the contoured predicted temps that have differing levels of meteorologist and computer input to try to cover for elevation and marine influences. There’s ZFPs (zone forecast product), which were common to see during the old TWC local forecasts, that tend to have ranges for an entire forecast zone (ie lows in the mid to upper teens). The popular ones now are the point-click forecasts on their site using the zoomable google maps that give you a forecast grid around your neighborhood. And then they have specific point forecasts for the airport ASOS weather stations. When I did the national collegiate forecasting contest it’s for designated airport sites for 2 week intervals and that’s all we forecast for…high, low, precip, and peak wind gust. Least error wins. So if we had PNS on the schedule I’d only be forecasting for the airport and not necessarily worried about your strawberry guavas.
But yeah, the important thing to know is how your microclimate works in comparison to the official airport sites and the various forecast outlets…and it seems you have a very good read on that. But if you’re hitting upper 10s every winter then you’re technically 8b and that’s becoming a decent zone push for z9 fruiting plants. I used to push here with multiple figs, but it becomes a lot of work. I’m not sure I’d want to design my food forest around zone pushing plants when one extreme night could ruin it all. Just my $0.02.
If you want to grow fruit, not trees, get a high tunnel for winter protection. On a sq ft basis my greenhouse is 10x as productive as outside. That’s for stone fruit. Figs are 100x as productive. Citrus and mango are impossible outside. But easily feasible in a greenhouse.
In Northern FL you just need protection on a few nights. A high tunnel is perfect for that. Cover with a single layer of clear poly during the freeze season and provide an adequate heater. Have roll up sides to control heat on sunny days. Cover with bird netting in summer or leave it open. You’ll get more fruit on the borderline fruits and also be able to grow most things they can in south FL.
My stonefruit and mango are planted 7ftx3ft. I’ve had as close as 5x1.5 to 8x4ft all worked.
One of our local nurseries just set up some thick skinned tunnels. With humidity and heat control. The plants inside are amazingly vigorous and healthy.
yes, i consider my backyard to be zone 8b though supposedly my town is 9a and 9b. i have mostly temperate fruit trees planted in the ground - apples, pears, plums, nectarines, apricots, figs, pomegranates, mulberry, blueberries, blackberries, persimmons, citruses, goumi, feijoas, loquats, yerba mate, cherry of the rio grandes, cattley guavas. i do have lots of bananas but those are easier to protect than other tropicals. hoping to plant cold hardy avocados once they’re mature. i have all my tropicals in pots, guess they’ll have to stay there.
yes, i realize if i ever want to put tropicals in the ground i need a heated greenhouse. hopefully one day in the future once i have a better microclimate.
Once the trees get big enough, they will likely still fruit fine under the outer canopy. The big trees growing around Seattle all seem to successfully bear fruit every year, even when we went into the teens after flowering. I’ll go check the one in the International District soon, but I suspect it’s still holding fruit from the flowering in Dec., even though it got down to about 15°F last month.
See, e.g., last year, after a winter low of 17°F or thereabouts:
ok good to know, my loquat trees are young and don’t have much for canopies, so very exposed. my premier (dwarf) is so tiny compared to my seedling loquat. probably not going to bother with the grafted varieties anymore and just get seedlings since they are more vigorous.
this was at 7 am this morning, the current temp at the time was 32F (#3 on my little weather station) while also at 7 am the weather channel was reporting 38F, accuweather said 37F and weather underground said 37F. look at the variation of the weather stations in my area. (#1 & #2 are inside my greenhouses)
my low this morning was actually 30F (#3) and i could see frost on the ground. btw #1 and #2 are my greenhouses which i insulated with cardboard, landscape fabric and blankets. i need to start recording every low i am getting on a calendar for every day in Dec, Jan, Feb and compare to the weather outlets histories. the coldest day i experienced here was mid 20s for the highs and upper 10s for the lows probably in 2018 or 2019 winter but when i go back to try to find that date (on weather underground) i can’t find anything even close to those numbers and it shows me Pensacola airport history only, not my area. i really feel like i am going crazy because i can recall that day very clearly - i was on the beach and my toes were numb.
Does the temperature sensor with your weather station have a radiation shield? If not the sensor probe/enclosure could lose excessive heat to space with clear skies and read lower at night than nearby shielded stations. Fan aspiration improves accuracy as well unless you have continuous wind flow to warrant passive shielding.
And yeah, these can read a little too cold on clear nights as well. What we’re trying to measure is the temperature at 1.5-2m. The sensor is just going to report the temp it “senses”. So if the enclosure is losing excessive heat to space, the sensor will just measure the temp of the enclosure surface which isn’t necessarily representative of the true 2m temperature even if we mount it at 2m. It may only be a couple of degrees difference, but I thought I’d just point that out.
Those Davis stations with the fan aspiration pull the air in through the bottom of the chamber, pass it over the sensor, and then exhausts out through the top. So it protects the sensor from radiative effects while providing rapid response and accuracy. Just thought I’d throw in my weather observing $0.02.
evidently i can’t post links yet. if you google for “pics of the yard.- several species, new orleans” you’ll see pics of some tropical fruit trees that can handle at least 21F.
according to “florida natural farming” on youtube, bananas share potassium with nearby fruit trees which gives them more cold tolerance. he usually cites his sources in the video description but i can’t remember which video it was. i don’t think it’s sharing, i think it’s trading. plants trade their surplus resources with each other via mycorrhizal fungi.
edit: greenman62 has a relevant post “nitrogen fixing plants and fruit trees” as well as “a couple of plants back from 20F”. i’m looking through all the threads he started.
In general, any thermometer with an open view of the sky is going to have accuracy problems on those clear, calm nights, so the “regular” thermometer also is inaccurate if it doesn’t have shielding. Here’s what I do for shielding on mine (mylar around a PVC pipe that has a rain cover allowing air flow), but this is also intentionally mounted lower than an official weather station because I want to know what the cold air is like pooling around the base of my trees:
no cold protection for these plants? i protected my subtropicals with frost cloths & tents when we had a deep freeze back in January, reported low was 20F, mid 20s overnight. my in ground pitangatuba (mature tree) was killed and my younger potted one in the greenhouse was damaged, natal plums had damage but are still alive. cherry of the rio grande trees defoliated a bit but overall not that damaged. my seedling surinam cherry tree in a pot in the greenhouse defoliated but is growing back new leaves. pitomba also in a pot in greenhouse got damaged but is alive. moringa and neem seedlings were in the greenhouse and got badly damaged but still alive in the lower trunks. a white sapote in a pot in the greenhouse defoliated but is growing back new leaves.
