home and fences round logo

Soil Temperatures for Planting: What to Know and Complete Guide

Jelena Maric
Agricultural Engineer

Plant molecular mechanisms and functions depend on temperature. For plants temperature is only an environmental factor, they don’t usually have ways to thermoregulate. They can’t generate physiologically relevant amounts of heat, with an exception of some large flowers and carnivorous plants that “heat up” their flowers to attract their prey thanks to an energy dissipation method known as the mitochondrial alternative pathway. Plants cannot generate as much heat as other plant tissues, but even if they are not able to regulate their organ's temperature, they have other ways to cope with harsh conditions.

The responses that lower-than- or higher-than-optimal temperatures trigger in plants tend to end up in decreased growth. Much like us, plants have an economy, it’s called carbon economy; they need to allocate the carbon assimilated during photosynthesis. In perfect conditions, it will be used for vegetative growth, flowering, fruit loading, and seed production. When conditions aren’t exactly right, plants use carbon to produce molecules that help them endure the bad times.

If you want your plants to be healthy and strong right after planting, you should make sure to plant them under the right temperature conditions. In the tropics, you don't have to worry much about this, the temperature is mostly stable throughout the year, and there you might worry about other factors, temperature only becomes a worry under extreme weather conditions, although sadly such events are occurring more frequently. On the other hand, temperate zones suffer strong shifts in temperature with the passing of the seasons, such changes are relevant for the plant life cycle. When you are planting, either seeds or transplanting a seedling or a grown plant, bear these next few ideas in mind.

The Right Temperature for Planting

There is no such thing as the exact perfect temperature for sowing or transplanting, but there are ranges, and their upper and lower limits vary between species. You can find this information in commercial seed bags or ask your seeds provider. There are also myriads of information about the right conditions for planting; they are scattered across scientific papers, agronomic books or guides from official institutions, commercial seed provider's instructions, greenhouses bulletins, blogs, and more. There is so much information that it can even become a challenge to find it and it can also be difficult to tell who’s right and who’s wrong when discrepancies are found.

In case your seeds come from a commercial provider, in other words, you bought them in the supermarket or a gardening store then following the instructions they come with will be the best way to proceed. Seed companies process millions of seeds and they have standardized methods to maintain the line of the plants so that their results are equal on any bag they sell. If the case is that you’re using your own seeds or seeds that you got from a friend’s harvest, things could vary a little.

Plants are organisms that show large plasticity to acclimate to their environment. They cannot migrate if conditions turn difficult or if they were planted in an environment where weather conditions are not exactly their optimal. When this happens plants find ways to “adapt” to the new conditions, they resist and survive until they are able to thrive there. (Tuteja & Gill, 2013)

Adaptation vs. Acclimation

When it comes to changes that allow one organism to survive in an environment that it is alien, “adapt” is not the right word to use. Adaptation refers to a long process (millions of years, usually) in which genetic changes become fixed in the genome of all the individuals of a population. This means that when the process of adaptation is complete, the environmental conditions that were once new are now their optimal ones. On the other hand, when we speak of short periods of time we should keep in mind that adaptation is not exactly taking place, that what is happening is actually called “acclimation”. Acclimation is a different process, one that can happen inside a sole individual. It occurs to the extent that its plasticity (which happens at the transcriptomic and proteomic level) allows it; some organisms are more plastic than others depending on their species and biogeography. Basically, an organism from a species that is native to a region in a temperate zone and that lives there has great plasticity to deal with seasonal changes, but one that lives in the tropics, where conditions are very similar all throughout the year is not necessarily as plastic, because it’s species did not evolve to sustain strong environment changes. Anyways, it’s not terrible to use the word adaptation when we’re referring to acclimation, because it’s just more common to use adaptation. It’s just good that you know there are different processes taking place at these two levels, “adaptation” referring to an evolutionary process and “acclimation” referring to an auto-ecological process, experienced by one organism only.

Besides adaptation and acclimation, there’s another, kind of intermediate, process called intergenerational memory. This means that even if genetic changes aren’t fixed in a population, a plant's epigenetics can make its way into its progeny, it may sound like a lot of information or crazy talk but it will be important if you are trying to get a plant to grow in an environment that is different from the one it’s coming from. Why let the plant struggle and acclimate to the new conditions, as you know it is possible for them to do so, but it’s also possible that all that effort will hamper growth and let the plant susceptible to pathogens, or that the changes will be too much for it and at such an early stage if you’re dealing with seeds or seedlings, it will not be able to adjust and die if you don’t make conditions right. The problem here is that realizing that soil temperature is the cause of our little plants not developing properly is a difficult conclusion to arrive at, apart from obvious extreme temperatures, it’s just hard to notice it. The same goes for when we move a plant from a plant nursery or store to our garden, the best we can do is try to make sure its process of acclimation to the new soil temperature and conditions is as smooth as possible.

Make Plant Acclimation as Smooth as Possible

You don’t need to start throwing buckets of ice on your garden’s soil if it’s too warm for your new plants, that would be a lot of work and wouldn’t really make sense, because you would end up making the conditions negative for other living organisms of your garden’s soil. The only practical way to cool down the soil is to add some shadow and water constantly. The only problem with the shadow is that if excessive, it can limit your plant's growth, so make sure that it covers the soil and plants during the warmest time of the day when the sun is more direct but it allows them to receive natural light during the morning and afternoon.

Warming the soil is also possible, an easy trick you can apply that can raise the temperature of the soil surrounding your seeds or seedlings is to place a boiled egg right next to it. For larger plants, you can use a glasshouse or even an open chamber (OTC). OTCs are used in climate warming scientific research to learn about what can occur to plants and other living organisms communities as the global temperature increases. (Hollister et al, 2018). You could give this a try, OTC’s offers protection from the wind and retain heat from the sun for longer, you can design them of any size that fits your garden.

Besides the passive strategies to warm up your garden’s soil a little bit, there’s a simpler method that just takes patience, you just have to make sure to plant on time. Weather conditions, though changing, usually remain stable for several days or weeks before a strong change, this will play in your favor because your new plants will be more resistant and resilient to the changes once they have, let’s say “settled in”, in your garden.

Monitor Temperature, That’s The Key

There are easy ways to monitor temperature conditions so that you determine the right time for planting, and if you are sowing seeds you can even set up a seed tray to not only monitor but also control conditions to be perfect for your plants. The most basic way of monitoring and preparing for planting is to follow the weather channel and the passing of the seasons, be ready for spring and begin to sow then. If you want to be more precise, because the plants that you have are too special or delicate, or if you’re planting already past spring then you can track soil temperature with a soil thermometer. There are many types so don’t let tech or a short budget limit you, there are affordable, easy-to-use devices that’ll let you keep track of your soil’s conditions.

Summary

Plants have optimal ranges of temperature to germinate, this is well recorded for the most common plants and in general, they don’t go below 20ºC/68ºF or above 30ºC/86ºF. Some plants are adapted to cold and some to warm temperatures, so always make sure to learn more about the specifics of a plant if you don’t know it well so that you can provide it with the best conditions to promote germination. Keep in mind if your plants show signs of acclimation to the weather of a specific locality that diverges from the species' native region. Try passive methods for cooling or warming the soil surrounding your plants and keep good track of the temperature to know the best times and areas of your garden to favor your plant's growth and development.

Summary

Plants have optimal ranges of temperature to germinate, this is well recorded for the most common plants and in general, they don’t go below 20ºC/68ºF or above 30ºC/86ºF. Some plants are adapted to cold and some to warm temperatures, so always make sure to learn more about the specifics of a plant if you don’t know it well so that you can provide it with the best conditions to promote germination. Keep in mind if your plants show signs of acclimation to the weather of a specific locality that diverges from the species' native region. Try passive methods for cooling or warming the soil surrounding your plants and keep good track of the temperature to know the best times and areas of your garden to favor your plant's growth and development.

Leave a Reply

Your email address will not be published.

WELCOME TO H&F
Disclosure
homeandfences.com is reader supported. We independently recommend methods, ways, products etc. As amazon associates we receive commission for every qualified purchases. More Details>> 
crosschevron-down linkedin facebook pinterest youtube rss twitter instagram facebook-blank rss-blank linkedin-blank pinterest youtube twitter instagram