Euphorbia in pots – A Comprehensive Guide
Euphorbias add a vibrant touch to any garden and are ideal plants to grow in pots because they are drought-tolerant and need poor soil with good drainage, which is simple to provide when grown in containers.
These resilient plants thrive in containers, offering a burst of colour and unique textures, making them perfect for small-scale gardening.
Euphorbias are perfect for outdoor pots because some are quite cold-hardy, and the more tender types if kept in smaller pots, can be easily moved to a shelter during the winter. I have prepared a Euohorbia hardiness chart to guide you on the best ones for your climate.
There are a few possibilities for euphorbias in pots, and the type you choose will depend on your preference for its shape, flower and foliage colour.
The striking Euphorbia rigida (Gopher Spurge) forms a compact growth of bluish stems and bright sulfur-yellow flowers. The elegant E. characias (Mediterranean Spurge) is an architectural beauty. The charming E. myrsinites (Myrtle Spurge), has tentacle-like stems that tumble over the edges of the pot.
But whichever one you choose will need the right conditions. The article will guide you through the steps you need to take to grow Euphorbias in pots successfully.
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How to plant Euphorbias in pots
This section will discuss the key points you need to consider when planting Euphorbia in a pot.
Choosing a pot for a Euphorbia
When you choose a pot for your Euphorbia, you should consider other important things besides aesthetics.
Anything that can hold soil and drain water at the bottom can be used as a plant container. However, the container’s size, shape and material are key in determining the success of your potted plants. These key aspects directly affect the water availability and insulation of your plant.
The container size
The general rule is the larger the plant, the larger the container.
If you would like the Mediterranean spurge, which can be quite large (80 cm /2.6 ft high and 60 to 80 cm /2 to 2.6 ft wide), you must consider a large pot. If you have limited space, the smaller and more compact Gopher spurge (40 to 50 cm /1.3 to 1.6 ft high 60 cm /2 ft) wide), will be a better option because it will only need a medium-sized pot.
If you love to see cascading stems, then go for the Myrtle Spurge. This spurge is not very tall (20cm/0.6ft), but it can grow rather long stems (40 to 50 cm /1.3 to 1.6 ft). So you must consider a pot that can accommodate these spreading stems. A tall vertical container will let the stems cascade down, which looks lovely. You can also opt for a wide horizontal container, but in this case, the water retention is higher, so you will not need to water it so much.
However, growing plants in containers will not allow them reach the same size as when grown in the ground. Pots limit the growth of roots and, therefore, the size of plants.
Basically, the container needs to be big enough to provide room for the roots, hold the necessary water for the plant, protect from winter temperatures, and be stable not to tip over.
If your pot is too small:
- The Euphorbia will become rootbound, and growth will be stunted.
- The soil will dry out quickly.
- It will be more exposed to winter temperatures.
- It may fall over easily because the pot is unstable for too big of a plant.
If your pot is too large:
- The soil will stay wet for too long because the roots will not be able to absorb water from all the soil. This will cause the roots to stay damp and possibly rot.
Aesthetically the size is also important. There needs to be a balance. A common design rule is the container should be about half the height of the plant. But in the end, it is really up to your taste, of what looks more pleasing to you.
I suggest you choose the size of your pot based on the size of the pot where the euphorbia is currently in. As a general rule of thumb, you should upsize 5 – 10 cm (2 – 4 inches) in diameter. This will allow extra room for growth as the euphorbia matures.
The plant will be better off if you change the size of the pot as it grows, instead of planting it in a large pot right away.
Your euphorbia will give you 2 important signs that it needs to be repotted, such as:
- It needs to be watered more frequently
- The roots start growing out of the drainage holes.
Generally, the euphoria will need to be transplanted once every two years until it grows to mature size. Nevertheless, keep an eye on it for the signs.
The best time to change your euphorbia to a new pot is during the spring.
Make sure the container is larger than the current one, has sufficient drainage holes and has good-quality soil.
Remove the euphoria from the current pot, loosen its roots and then place it into the new container. Cover the roots leaving some space below the rim to allow room for watering. Finally, water it thoroughly.
Keep in mind that euphorbias release a milky sap that can be irritant to the skin, so always wear protective gloves when managing this plant.
The Container Shape
When choosing the shape of your container, you should consider not only its ornamental characteristics but also its stability and water retention.
The shape of the container determines if it´s stable enough to keep the plant from falling over with the wind. This is especially important if the plant is tall and dense.
Square and rectangular pots are the most stable. Then come the cylinder pots. Finally, the least stable ones are the more traditional inverted cones which tend to tip over easily.
The shape of the container affects the water retention capacity. Even when containers have the same volume and potting mix, water will dry out faster in a tall, narrow container than in a short, wide one.
This is due to the perched water table, which will be at the same height regardless of the shape and size of the pot.
The image shows two pots with the same volume and potting mix and, therefore, the same perched water table height.
As you may see, the tall, narrow pot holds less water than the short, wider pot. Also, the water is further away from the roots in the taller pot.
So with this in mind, you will choose a pot that is preferably tall and narrow. If you prefer a more horizontal pot, then you need to water it less and more frequently to avoid too much water retention near the roots.
The container material
The material that the pot is made of should also be considered when selecting a pot for your euphorbia. There are different materials, such as Plastic, Metal, Cast cement, Terracotta, Glazed clay, Wood and many more.
The material has a significant impact on the drainage of the soil and the insulation of the roots.
Pots made of plastic, metal and glazed pots will resist water loss and keep the soil moist for longer.
Pots made of porous material such as terracotta or wood will soak water from the soil and release it easily, enabling quick soil drainage.
For your euphorbia, which prefers dry and well-aerated soil, you will want to choose a pot with a more porous material such as terracotta, or wood.
The temperature of pots with a porous material such as terracotta and wood will not fluctuate as much as plastic or metal materials. Therefore the porous material is a better option to insulate the roots from extreme temperature fluctuations.
However, in the winter, terracotta pots can break easily in freezing temperatures.
This happens because the water that gets into the pores will expand when frozen, cracking the pot. So to minimize this, you may want to wrap the terracotta pot with plastic to prevent it from getting wet.
The best soil for euphorbias in pots
Mediterranean plants, such as euphorbias, need well-aerated soil with good drainage. Soggy soil is a real problem for them.
If you want a happy euphorbia, you must imitate its natural environment as well as possible, starting with the soil.
The potting medium for your euphorbia should have the following characteristics:
- Well aerated
- Good drainage
- Hold on to nutrients
- Retain some moisture
There are many recipes for potting mixes, but for drought-tolerant plants like euphorbia, you will need to add more quantity of an ingredient with large particle sizes, such as coarse sand, vermiculite or perlite. This is necessary to ensure the potting mix has excellent drainage and aeration.
The image shows how the amendment with a large particle-sized ingredient (ex: coarse sand, vermiculite or perlite) affects the soil’s drainage.
How to care for euphorbias in pots
If we plan to grow euphorbias in containers, we must not forget that plants in containers are more susceptible to the dryness of the soil, the effect of extreme temperatures and the inaccessibility to nutrients.
Euphorbias are tough plants and tolerate harsh environments. However, they still need special attention when grown in containers.
Because containers have a limited quantity of soil, watering and fertilizing become necessary, even for established euphorbias. Additionally, the roots in a container are more exposed to temperature fluctuations, so care must be taken to protect the roots.
How often to water euphorbias in pots
Even though euphorbia plants are drought-tolerant and do not need to be watered once they are established, this is not the case when they are grown in containers.
How often you need to water your euphorbia will vary depending on the weather, the potting soil, the type of container, and the exposure of the container to sun and wind.
- Weather: During the winter, the plant will need much less water because it is not actively growing and is not as hot.
- Soil: If your potting soil does not drain easily, you must water it less frequently than if it has excellent drainage.
- Pot material: If your pot is made of a porous material, you will need to water it more frequently than if it’s made of plastic or a glazed material.
- Pot size: If the pot is smaller, it will need more watering than if it´s larger.
- Exposure: If your plant is exposed to many hours of sun and winds, it will need more frequent watering than if it has some shade and is sheltered.
This means there isn’t a “one fits all” schedule for watering your plant. So you must observe your euphorbia regularly to see if it needs watering.
How to check if your euphoria needs water
You should not wait for the plant to show severe signs of wilting due to insufficient water or die from excess moisture.
The easiest way to know if the plant needs water or has excessive moisture is to stick your finger in the soil and feel how dry or moist it is.
How to water your potted euphorbia
In the case of drought-tolerant plants like euphorbias, you will need to let the soil dry out completely before watering again. The rule is to water deeply and infrequently.
When you notice the soil is dry, it is time to give it a deep watering. You must wet the soil completely until water drips out of the drainage holes.
After this, leave it until the soil has dried out again. You may be surprised by how long your euphorbia can go without water. You are better off giving it less water than overwatering.
If you notice a gap between the soil and the pot, then you should press the soil against the wall of the pot to close this gap. Otherwise, the water will flow right out through the gap. This is more common when you have just potted your plant, and the soil is not yet tightly pressed.
Finally, you may want to cover the soil with some mulch, ideally gravel, to help conserve moisture. This will also give some extra protection from the cold temperatures of the winter months.
Overwintering euphorbias in Pots
A plant in a pot is less hardy than in the ground. This happens because the parts of the plant above the ground are hardier than the roots. When roots are out of the ground and inside a container, they are more exposed to cold temperatures.
Plants in pots are also more prone to freezing and thaw cycles. If your plant is in a sunny spot, it can warm up considerably during the day and freeze at night, which is very hard on the root system.
So to minimize the problems, I have the following tips:
- Choose a euphorbia that is more cold-hardy than your zone ( generally 2 zones under).
- Plant in a large container (but always matching the size of the plant). The larger the pot, the more insulation it will have around the root system.
- If the pots are not too heavy, move them into a cold frame, a shed or a more sheltered location outside and cuddle several pots together.
- Dig a hole in the ground, place the pot inside and cover it to the brim.
- Wrap the pot with a thick burlap, bubble wrap or straw layer.
Don´t forget to give your plant a deep watering at the end of the season and then keep an eye on it during the winter and water it when needed.
Usually, euphorbias will not need watering in the winter. Still, when they are in containers, they may need to be watered not to let the roots dry out which can easily happen in a container because of the limited quantity of soil.
Fertilizing euphorbias in pots
Like most Mediterranean plants, euphorbias prefer poor soils. However, when they are in pots with a limited amount of soil, they will consume all the available nutrients after a certain period.
So it is necessary to give them some fertilizer from time to time, to replace the nutrients.