Heat and cold resistant outdoor plants

Indoor plants are more or less easy to choose, because the environmental conditions indoors are quite stable. One of the biggest challenges when choosing outdoor plants is to find one that suits the climatic vagaries of the region. And if you are fortunate enough to live in a place with very distinct and extreme seasons, then it becomes an even more complicated task. If you don't want to live with moving plants every month or resign yourself to seeing them die and replant them the next season, then you need to get your hands on these heat and cold resistant outdoor plants.

why do plants die in extreme climates?

Nothing would be more beautiful and easier than to have a plant, let's say for example a nice olive tree, and watch it grow and become beautiful under the radiant summer sun and then under an incredible snowfall. This can only be achieved with plastic plants, because all plants are ectothermic organisms, i.e. their temperature depends on environmental conditions because they lack a thermoregulatory mechanism.

Humans have an amazing body, which is able to keep itself at a constant temperature even when the external temperature is very different. For example, if it's hot, we start sweating to cool down and if it's a bit cold, we shiver to recover heat. Plants do not have this system, but depend on the external temperature. Temperature is an important aspect because it can interfere with the proper development of processes such as photosynthesis, respiration, germination, nutrient uptake and more.

When plants reach a temperature for which they are not prepared, they become stressed. In the case of low temperatures, cold can cause disturbances in membrane function, protein synthesis, nutrient metabolism, photosynthesis and respiration. It also causes problems in the water absorption mechanism. Stress, whether from heat or cold, causes the plant to invest its resources and energy in maintaining vital functions, thus neglecting other needs such as the maintenance of leaves and fruit. If stress conditions persist, the plant dies.

One of the biggest enemies of plants is frost. Freezing and thawing often causes air bubbles to form in the plants' fluid transport system, which can block the system and kill the plant. Some plants have evolved evolutionary mechanisms to withstand cold temperatures. Some plants, such as oaks and hickories, avoid frost damage by dropping all their leaves in autumn. This ensures that the flow of water between leaves and roots is shut off.

Some species go into dormancy, consume the minimum required water and nutrients, and grow again when the weather is more favourable. Plants such as poplars and birches have developed narrow water transport cells that avoid the problem of freezing blockage. And there are plants that are naturally equipped to deal with these extremes.

How to choose the perfect plants for the climate

The simplest trick to choosing outdoor plants that are able to withstand extreme weather is to use local species. It seems like a no-brainer, but we are so used to looking for exotic and different plants that we overlook those species that are made to live and adapt to the climatic oscillations of the region. Find out which region of the peninsula you are in and which plants tend to grow in these latitudes. Another way is to go for a walk and look at the trees and plants that grow in public parks or open gardens.

It helps to be clear about the maximum and minimum temperatures in the region, as articles on plants hardy to such climates often make this information explicit. It is also important to take into account the location of the space where you will place the plants, as the incidence of the sun's rays on the plant in summer depends on this.

If you are more worried about low temperatures in winter, you can always learn some tricks to protect your plants from frost. For example, make sure the soil is well drained to prevent the roots from freezing. Another trick is to stop fertilising regularly in autumn, as this alerts the plant that it is time to start preparing for winter.

Don't think it's all negative. When plants live in places with such different climates, they learn to adapt their cycles to this, plus they are less affected by insect pests, which do not tolerate low temperatures. This saves you the use of pesticides and allows you to breed healthy plants.

Plants resistant to extreme climates

• Oleander

The scientific name of the Oleander is Nerium Oleander. The first thing that strikes you about this plant is its clusters of pink, yellow or white flowers, which grow in spring. It is an evergreen plant, i.e. it will keep its green leaves all year round. This shrub, which can grow up to 6 metres high, is practically maintenance-free. It is suitable for beginners and its requirements are very simple.

The oleander can tolerate temperatures down to 15 degrees below zero and about 40°C. Watering has to be adjusted according to temperature and season, so in summer it will require more water. The substrate must be very well drained, so it is usually mixed with a little sand. You can fertilise in the warm season. It grows very fast, so it will become a focal point in your garden. It has only one drawback: it is considered the most poisonous plant in the world, so if you have pets you will have to be very careful. However, it is not attractive to animals because of its bitter smell and taste.

• Japanese Maple

The Japanese maple is a deciduous tree with beautiful foliage that turns orange or red in autumn, just before it falls. It reaches a height of 8 metres and can survive fearsome frosts of -18° C and up to 30° C in summer. It is very easy to care for and can even be kept in pots. I am sure you will love the shape of its leaves.

This tree requires a very well drained substrate, if possible with a slightly acidic pH. Watering should be copious and more or less frequent, because it does not tolerate drought. It prefers bright places, but where the sun's rays do not reach it directly. If it is in a pot, it should be repotted every two years into a larger pot. It prefers humid environments, but avoid spraying its leaves with water, as this hinders its respiration.

• Aspidistras

It is a green, herbaceous, perennial plant. Its long leaves, which can reach 60 cm in length, have an incredible bright green colour. Very hardy and easy to care for, it prefers semi-shade and is able to live in high temperatures up to 40° C and in frosts down to -10° C.

The charm of the Aspidistra lies in their volume, as they are perfect for adding lushness to the garden. They are perfect for window boxes and the like or to cover the bases of taller plants with a woody base. They are great for shady places with little sun. Moderate watering, although they can tolerate drought conditions.

• Roses

Roses are among the most popular and appreciated flowers, not only for their beauty but also for their delicious scent. Although they may look like delicate flowers, roses are actually very hardy and versatile plants. They can be planted in pots or in the ground and can withstand temperatures ranging from 38° C to -12° C in winter. They can reach a height of 30 cm to 20 metres, depending on where they are planted. Roses will brighten up your garden from spring until October if they are in the right conditions.

Watering roses should be moderate, 3-4 times a week during the summer and less frequently during the rest of the year. Roses need full sun to live, so you can put them outdoors with complete peace of mind. want more flowers? You can fertilise it with a special fertiliser for this type of plant. This plant tolerates pruning very well, although you can still keep it beautiful by cutting off the dried flowers.

• Garden Plum

The Garden Plum or Prunus Cerasifera pisardii is also known as the red plum tree. It is from the same family as the cherry, almond and peach trees and will become the darling of the garden. It is almost impossible not to fall in love with its thick purple foliage, and in spring with its white or pastel pink flowers. It is an ornamental deciduous tree, as its fruit is not edible, and it can grow up to 8 metres.

The plum tree requires abundant sun and deep soil, although if temperatures are too high in summer, a little shade would not be a bad thing. They are low maintenance, and although they prefer clay soil, it is sufficient to give them well drained soil with organic matter. Watering should be moderate, although plum trees tolerate drought quite well. They should always have well-drained soils, waterlogging is fatal for them.

• Carnations

The floral icon of Spanish culture is a plant that withstands extreme climates very well, although without exaggeration. In theory it can tolerate a minimum of -5° C and a maximum of 30° C, but it is best if they are not exposed to the most terrible frosts. The carnation, or Dianthus Caryophyllus, is a herbaceous perennial that is very easy to care for. The best thing about this species is that its flowers will accompany you from spring to autumn, they come in many colours and are sure to add a touch of colour to your space.

Carnations require liquid fertiliser for flowering plants once a week during spring and summer to stimulate flowering. They require little care, but it is best to remove dried flowers. Water only when the substrate looks dry, as although they require water to grow and thrive, waterlogging should be avoided. They love light and sun, so they are perfect for that well-lit corner.

• Lavender

This is one of my favourite plants, because it has such a delicious and relaxing aroma that it can turn any corner or garden into an oasis of peace. What few people know is that this semi-shrubby perennial plant, so common in the Mediterranean region, can withstand temperatures as low as -5° C. Lavender is very hardy and will not demand much from you to bloom and fill your garden with its purple colour in summer.

Lavender loves the sun and if you provide it with a rather alkaline substrate, it will grow happily. It is not necessary to fertilise it, in fact some people advise against it as this can cause it to lose its scent, but if you have it in a pot, you can add a little liquid fertiliser at the beginning of spring. It is important to prune it in autumn to stimulate its flowering.

• Excelsa Palm

Many people think of palms as plants of tropical origin, but the truth is that the fan palm or trachycarpus fortunei is a wonderful palm tree, as it is able to withstand the most extreme climates. As if that were not enough, you can even plant it in pots or small gardens; it can reach up to 15 metres in height, but its trunk will always remain at a maximum thickness of 40 cm.

What makes this palm different is that it is covered with fibres that protect its trunk, so it can withstand temperatures as low as -17° C. You can place it in full sun or semi-shade and it will grow happily. It requires frequent watering, up to 3 times a week and if you want to make it really happy, then use organic fertilizers such as guano.