a question about ideal temperature in plants

-I am a little confused about the right temperature in some plants species. Can you pls help me understand if there is any difference between the ideal temperature in the same plant ( lets say for example Felitsia amelloides) , when we keep it into the garden soil or in just a pot?
- I have used the example with this plant , because i read somewhere that whenever we keep it in a pot the temp. must never below +10 degrees of Celcium . Although i know that is a tender perennial and in mild winter can stay outside to low temperatures about -4 degrees of Celcium...Help pls
vTr

A container can cool off much colder than the soil. The ground has some insulating effect that protects the roots from freezing.

In the summer a container can get much hotter than the soil in the ground. Especially if the sun hits the container. The roots can get overheated and die.

The temp is NOT in the PLANT, it's the soil temp, you need to get that right as well as the overall
air / sun temp, also moisture, light, SUN / SHADE, are also important too.

I think Diana has covered the best advice as regards growing things in pots, this type of pot growing is a bit more difficult as the temps can vary hugely from hour to hour in sun / cold even wind can reduce a tender plant to a leafless skeleton.

I personally don't grow this plant as it's way too tender for UK, best guide is to try find out where the plants (any plant) originate from, it's natural habitat, like IF it grows up the mountains of China, you learn these plants mostly like moist shaded planting areas and are NOT tender. Your plant may be more tropical requiring Humid atmosphere with well drained soil BUT again, do a search on Google or here on Dave's for that specific plant, there will be information somewhere to tell you how best to care for the plant in cooler temps.
Hope this gives you ides where to try get more info.
Kindest Regards.
WeeNel

It doesn't matter what plant is pot grown but a consideration of potted plants growing in the sun is that the soil in the confinement of pots heat up fast therefore can literally burn roots. I have grown plants in pots and always place the pots to receive morning sun on the East side of my house. This is in regards to any type of plant. Likewise quick to freeze.

In contrast, the roots of plants grown in the garden are insulated from the heat and freezing. There really is no "ideal" temp for every plant. All have a wide latitude in temp. It also depend on what type of plant. As a guide, some like it hot, others cool but all require between 60F (15C) and under 85F (27C) in the gaden. In pots 70F (22C) to 75F (24C) to prevent roots from burning.

If you are growing plants in pots, there is no way to control temp. except to grow in in less sunlight. You also have to consider climate.

I lived in MA for 20 years before moving to NE, then WY. I have garden in all 3 states. There is a big different in sunlight. I learned that when a plant needs sun, it will grow better, or just as good, with part sun in WY and NE. Our mid-day sun is very hot since WY is 51,000 ft above sea level so close to the sun therefore hotter. In MA, no problem with mid-day sun.

This message was edited Jan 3, 2015 2:46 PM

A few more things to bear in mind when growing container plants in the sun, based on my experience here on a rooftop patio... container life is going to be more stressful for plants than an equivalent exposure situation in the ground.

The smaller the pot, the wider the fluctuations in moisture and temperature over the average watering cycle. Very small pots can be impractical in full sun, even in a cool climate. My usual cutoff here is about 6" (15cm) for easy care without nesting.

By nesting pots of like sizes together, you minimize the area exposed to the sun and thus the heat danger which may result. The pot in front will protect the ones behind it. By huddling together, the plants do better in exposed situations.

You will see a significant difference in the "casserole effect" (root roasting situation) between light colored and dark colored pots. Avoid black or very dark pots in sunny situations, except with tough desert plants. Likewise avoid clear plastic (or white, nearly clear plastic) pots, as they can develop a serious crust of algae inside over time.

In areas where heat is an issue, clay pots may provide an attractive alternative for some plants. Because the water evaporates through the clay, it cools down the container and its contents. Until the pot goes dry of course, which will be much sooner on average compared to plastic.

Overhangs are very useful to provide protection to potted plants. They block the strongest vertical rays of summer sun without interfering with the kinder sideways ones. Over the course of the changes in season, you will notice light exposure changes in different places and you may want to move plants closer to structures/walls when the sun is strongest. This is not just because of the dangers of UV, but also (in many cases more importantly) to avoid cooking the roots in midday sun.

Another concern to add to Baja_Costero's wonderful notes:
A south or west facing wall can add to the heat load on the plants, in containers or in the ground. This may be beneficial in the winter, but can be way too much for them in the summer.

Yes, absolutely. A south facing wall with an overhang is one of my best spots here in winter. It gets lots of light, warmth from the adjacent bricks, and protection from excessive winter rain (an issue for a few rot-prone plants which like to go dormant then). The angle of the sun in the sky maxes out at 36° (less than halfway to vertical) here in the dead of winter so those plants get direct sun for most of the day right now.

One can get a little obsessive about protecting plants (guilty as charged) but I've noticed there is a big difference in temperature when pots are not sitting directly on the floor (in this case a concrete slab with tile on top). The temperature of the floor rises several degrees in the sun and again, while that may be a good thing in winter, it's not what you want in summer. I place my patio plants on tables, wood slats, old pallets, homemade furniture, whatever... anything that gets them a couple of inches off the ground and allows the free passage of cooling air.

That is why I recommended an Eastern exposure for morning sun. In mild climates, that would work in the winter also.

I looked up temp. for Athen, Greece for January. It will be in the 50's with many cloudy and part sunny days.


This message was edited Jan 5, 2015 7:54 PM

Sounds a lot like the weather we are having here. HIghs in the 50s, but at night it is getting down into the 30s.

Athens climate is not terribly unlike what we experience here and in coastal California, especially this time of year (on the dry side of Mediterranean). The big difference (from here anyway) is the heat in summer. Athens holds the record for the highest temps recorded in Europe. That means you really have to protect your pots from the sun in summer. Depending on how much it cools down at night, you might have to put them in mostly shade.

I'm in Port Hedland, Western Australia and I found all my plants died when summer came. It gets up to 100degrees here and no amount of water could save them..

Plants are limited as to how fast they can take in water.
We see it here with squash and pumpkins in the summer. The leaves will wilt in the heat of the day, but they recover overnight. (Average summer highs are usually in the 80s, though 90-100 is not unknown, and no summer rain.)

Plants that die from the heat are usually unable to pick up enough water. You could try these plants in a place with good light early in the morning, but shaded by mid morning. See if that is enough shade for them. Filtered light through a tree might be enough for them. If they are still wilting, then making a plastic tent for them to keep the humidity up might help, but absolutely out of the sun! Perhaps a better idea is to select other plants.

No matter where you are in the world there will always be plants you cannot grow without extreme protection that may make it not worth even trying that plant. In places that are too hot, a cooling system in a greenhouse may be required. In colder places it may take a lot of heat to keep something alive through the winter.