Temperature
As with every other component, this is a layer to consider when you want to try hard growing your plants.
If you’re not in a climate that’s already ideal for cacti and succulents, you have more considerations for this than those of us blessed with their preferred temperatures. If you’re growing them indoors, they won’t experience the 100F+ highs of summer, or the nights near freezing where you have to keep them bone dry. I’ll freely admit: I don’t have much experience with that type of growing! As soon as my seedlings or imports are able to go outside, I stick them out there, and work them into the greenhouse. Indoors, I would imagine you need to be far more sparing with water, and more attentive to the quality and intensity of your artificial lights to encourage the hard growth you may be seeking.
For those fortunate enough to live in climates with fairly mild winters (zones 8 and above), your greater consideration is how temperature impacts your pots and the plants in the ground.
Heat is (for me) the more worrying consideration over cold. During cold months, I severely restrict water, and it’s generally fine. Most things are dormant, or my winter growers are getting water to their hearts’ content and are blooming and happy as can be.
It’s summer that’s hard.
Terra cotta pots dry out quickly. Plastic pots don’t insulate against heat. Staging pots, or show pots, are even worse for heat. The high temps dry out soil quickly, and in a greenhouse, temperatures can quickly reach extremes that most plants wouldn’t experience except for extreme cases. As a result, they’ll need more water, or more shade, than they might otherwise.
The thing to watch for is dry soil, and baking the roots. In pots, it’s very easy for plants to overheat and roots to cook. In the ground, the soil takes far longer to heat up, and is much less likely to bake the roots.
Back to hard growing, temperature extremes are part of what our plants have evolved to cope with. With seasonality, you’ll get more natural growth periods, which include the stressful periods of not growing. The periods of rest, either in winter or summer dormancy, contribute to slower, more compact growth, and encourage the stress reactions of farina coatings, fuzz, and spines.
Temperature, in and of itself, won’t necessarily “hard grow” a plant, but it’s hard to accomplish without temperature extremes. One more element to consider!
