Oversummering poinsettias and making them bloom again

Your poinsettia can live on after the festive season – with the right care, it will bloom again next year too.

A poinsettia doesn’t have to end up in the bin after the holidays. You can keep it over the summer (oversummering) and make it bloom again. It’s not easy, but in this article we’ll show you step by step how to do it. It’s worth a try, right? The crucial details: Poinsettias like warm temperatures, but direct summer sunlight can damage them. With the right care – and a cool trick – they will stay healthy and be ready for their next big appearance.

• In brief: Oversummering poinsettias and making them bloom again
• Dormant phase after flowering
• Pruning poinsettias
• Repotting poinsettias
• Location and light
• Watering in summer
• Fertilising correctly
• Getting poinsettias to bloom again: The trick for colourful bracts
• Practical help for common challenges
• Interesting facts about poinsettias
• Answers to frequently asked questions
• Glossary

Don’t panic if your poinsettia starts shedding leaves after the Christmas holidays. This is completely normal. After flowering, your poinsettia will go into a dormant phase until April.

During the dormant phase, water your poinsettia significantly less for four to eight weeks, just enough so the soil doesn’t dry out completely. It goes without saying that you don’t need to fertilise it during this time. A cool, bright location with temperatures between 15 and 18°C is ideal now.

Unsure how to prune poinsettias? Pruning in spring is important. It promotes the growth of strong, new shoots that will ensure dense and beautiful plants in autumn. To make sure your poinsettia starts growing again, prune it in April before repotting. Step-by-step instructions:

• Use sharp, clean scissors to prevent infections.
• Cut the shoots back by a third to a half.
• Prune the side shoots as well, to encourage bushy growth.
• Always cut just above a leaf node.
• Remove as quickly as possible any dried, rotten or diseased shoots you find later in summer.

Tip: Wear gloves when pruning. Milky sap will ooze out at the cut points. Touching it can cause allergic reactions in people with sensitive skin, so we recommend wearing gloves when tending your plant. Those allergic to latex can also react to the sap and should avoid direct contact with it.

➡️ What happens in detail when you prune a poinsettia? We explain this in the article Pruning a poinsettia.

Always use fresh soil for repotting, preferably cactus compost or high-quality potting compost that you can make more free-draining with aggregates. Sand or perlite are good for keeping the soil loose and the roots well ventilated. A thin drainage layer of expanded clay or clay shards at the bottom and the pot’s drainage hole are enough to preventing waterlogging.

When repotting, be careful not to damage the roots of the poinsettia. Squeeze the old plastic pot to loosen the root ball before pulling it out. If the roots won’t come loose, cut around the inside of the pot with a knife.

Lightly shake off the old soil and remove rotten root tips with sharp scissors. Then add fresh compost on top of a drainage layer in the new pot and place the poinsettia deep enough so the top of the rootball is 1cm below the rim. Then fill the pot with fresh compost making sure the plant isn’t any lower than it was before. Water lightly, but only enough to allow the soil to settle.

Now your poinsettia has been repotted and pruned, it needs the perfect spot to live through the summer. Although the plant originally comes from the warm regions of Mexico, that doesn’t mean it loves the blazing summer sun – it’s more of a diva. But is the ideal location outdoors or indoors? In summer, you can either keep your poinsettia indoors or put it outside as soon as the temperature remains above 15°C, even at night. There are a few things to bear in mind:
• Poinsettias like light, but not direct sunlight, at least not in summer. If you place them outside, look for a bright but partially shaded spot – for example on a balcony or in the garden under a tree or canopy where the blazing midday sun doesn’t reach them. Direct sun can burn the leaves and damage the plant. Poinsettias are in the same boat as many other plants that aren’t typical bedding and balcony plants. Gentle morning sun is best.
• Make sure the location is sheltered from the wind. Poinsettias don’t like draughts and certainly not when the wind is constantly shaking them.
• Poinsettias also prefer temperatures between 18 and 22°C during the summer months, so avoid any extreme heat.
• If you decide to place your plant outside, check the weather forecast regularly. Heavy rain or hail aren’t good for poinsettias. If in doubt, bring it indoors for a short time.
• If you keep your poinsettia in the living room in summer, make sure it’s near a window, but not in direct sunlight. A spot by an east or west window is ideal. The light there is intense, but not too strong. Unlike in winter, a south-facing window without shade is not suitable in summer.

In summer, your poinsettia needs food. This is where fertiliser comes in, because the plant has high nutrient requirements during the growing season. From April, start feeding your poinsettia with a liquid fertiliser weekly or every two weeks. A normal houseplant fertiliser is fine.

If you have to buy fertiliser, make sure the nutrients nitrogen (N) and potassium (K) are contained in a ratio of approximately 1:1. (The concentration of the nutrients will be indicated on the bottle in percent). Follow the instructions on the packaging and stick to the recommended dose. Too much fertiliser can do more damage than none. Mix it into the water you are watering with and stir the solution so the nutrients are evenly distributed throughout.

Coffee grounds are often recommended as a cheap and environmentally friendly fertiliser for houseplants. The experts at weihnachtsstern.de advise against it. What’s left after brewing coffee actually contains some important nutrients, such as nitrogen or potassium. However, it’s not enough. Poinsettias need plenty of food to grow vigorously. Plants fertilised exclusively with coffee grounds are very likely to go hungry and won’t perform to their full potential.

Another argument put forward by proponents of fertilising with coffee grounds is soil quality. Coffee grounds can indeed improve soil structure by promoting the growth of certain micro-organisms. This has long-term benefits in the garden, but this effect isn’t relevant in a flowerpot. There, earthworms and the like play almost no role as guarantors of active soil life. Our advice: Buy good potting compost instead.

A common misconception is that you can simply sprinkle coffee grounds on the soil to fertilise your houseplants. This usually just leads to mould growth and sealed soil. This is when the nature of the soil is changed so it behaves as an impermeable medium. To use coffee grounds effectively, they would first have to be dried and then worked into the soil as a powder. Difficult when you consider how densely rooted a flowerpot is.

Summer is coming to an end and your poinsettia has had a quiet time and intensive care. Now comes the exciting phase: From September onwards, the plant needs to be prepared for its big winter show. And as soon as the temperature drops below 12°C, the poinsettia needs to be brought back inside.

To make sure the bracts of your poinsettia regain the colour of last year, there’s a small but crucial trick: light control! Poinsettias are short-day plants. This means that they need a certain amount of darkness to develop their coloured bracts. Experts also call this behaviour photoperiodism. From the end of September, do the following if you want to have a magnificent poinsettia again at Christmastime:

To stimulate its colour formation, your poinsettia needs to be in the dark for 12 to 14 hours a day. Exactly how much differs from variety to variety. So place your plant in a room with no light in the early evening or, to be on the safe side, cover it with a cardboard box for 14 hours every evening. Do this for 6 to 8 weeks. After that, the poinsettia will begin to develop its characteristic red, white, pink or other coloured bracts. This doesn’t just work at Christmas, by the way. You could also let your poinsettia bloom on another special occasion with an adapted cultivation method.

Make sure your plant isn’t exposed to artificial light when darkening the room, as just the smallest amount will disrupt the rhythm and delay flowering. Even the flickering of a television or the dim light of a street lamp is enough. From September onwards, stop fertilising. The plant now needs fewer nutrients and is preparing for the flowering phase.

When in its darkening phase, your poinsettia should still get as much natural light as possible during the day. Make sure the temperature remains constant. Between 18 and 22°Celsius is ideal. High daytime and low nighttime temperatures delay induction of flowers. This is when cells within the growing tip of the plant switch from a vegetative to a reproductive mode of development. As soon as the poinsettia starts to develop its coloured bracts, it likes things a bit cooler. A bright but cool place (around 15 to 18°C) is ideal so it can bloom vigorously.

Even if you take great care of your poinsettia (Poinsettia care: success guaranteed), problems can arise from time to time. Many of these can be solved. Here are the most common challenges and how you can tackle them to save your poinsettia:

Yellow leaves are a common sign that something is wrong. There can be many causes:

• Too much water: Poinsettias are sensitive to waterlogging. If the soil is constantly too moist, the leaves will start to turn yellow and fall off and the roots will rot. Water less and let the soil dry out well in between. Remove excess water from the drip tray or planter 15 minutes after watering. Your plant may recover.
• Too little light: If your poinsettia is in a spot that’s too dark, this can also cause yellow leaves. Place the plant in a brighter location, as bright as possible in winter and as good as your decoration idea allows.

If your poinsettia suddenly loses its leaves, it is usually due to a temperature shock. An abrupt change from warm to cold, for example due to a draught, cold water, an open window or moving outside, can cause the plant to shed its leaves. When it comes to location, poinsettias are one of the more sensitive plants. Place it in a sheltered spot and carefully accustom it to a new location.

If your poinsettia loses leaves, turns brown and dry, and the soil is already coming away from the edge of the pot, it has clearly not had enough water. This drying out can cause the plant to shed leaves to protect itself. Immerse the poinsettia’s root ball in a container of water and leave it there until no more bubbles appear. This allows the soil to soak up the water thoroughly. Let the plant drain well and remove excess water from the planter or saucer after 15 minutes at the latest. Cut back any dried shoots to encourage new growth. If it hasn’t been dry for too long, it may recover.

If your poinsettia just won’t bloom, it’s often because it hasn’t had enough darkness. If it doesn’t get enough (see The trick with darkness), it won’t bloom. Solution: Make sure your poinsettia has at least 12 hours (preferably 14) of absolute darkness per day from September onwards. No light – even artificial light – should disturb the plant.

If your poinsettia suddenly stops growing in the summer and perhaps gets brown leaves, it may lack nutrients. It needs regular fertiliser, especially in the summer, as it has high nutrient requirements. Feed your plant with houseplant food according to the package instructions to promote growth.

Poinsettias can become a target for pests if you keep them for more than just one winter. If the infestation is severe, it’s usually not worth the effort to combat it. The most common culprits are:

Aphids
These small green or black insects suck the plant sap and leave sticky residue, known as honeydew, on the leaves. Gently shower the plant with lukewarm water or use special pesticides. Indoors, you can combat aphids with beneficial insects such as lacewing larvae (Chrysoperla carnea).

Fungus gnat larvae
Black insects a few mm long that sit on the soil and buzz around the plants – these are fungus gnats. Adults aren’t harmful, but the larvae in the soil are problematic as they eat the root tips. Water less often, because fungus gnat larvae need moisture. Always let the soil dry out well between waterings. To check, you can put yellow insect traps in the pot. They catch the adult gnats. You can fight fungus gnat larvae indoors and outdoors with beneficial insects (Steinernema feltiae nematodes). There are also pesticides for use when you water. With patience, yellow insect traps will catch all the adult pests.

Whitefly
If there are small, white insects on the underside of the leaves that fly away when touched, the poinsettia has whitefly. If the infestation is severe, sticky honeydew forms on the upper sides of the leaves and they can then develop a fungus, turn yellow, wilt and die. Put insect traps in the pot to detect any pests early. Indoors, you can fight whitefly with beneficial insects (Encarsia formosa, parasitic wasp). There are also sprays.

Scale insects
You can spot scale insects on a poinsettia by small, raised dots on the stems and leaves, which can be brown, as well as by sticky honeydew and yellowed leaves. It’s difficult to get rid of them, so it’s best to dispose of the plant in the general waste (not compost) so the scale insects don’t spread to your other plants.

Pythium
Pythium is a fungal disease that causes the roots to rot. It starts at the tips and spreads to the entire root. The leaves remain green, but they become limp and wilt. Pythium can’t be combatted at home. All you can do is always take good care of your poinsettia. This includes not watering it too much and fertilising it enough, but not excessively. In professional growing, there is the option of mixing special bacteria into the soil. These are intended to act as antagonists to keep the harmful root fungus in check.

The poinsettia, also known as the Christmas star, is one of the most popular flowering houseplants in winter, especially at Christmastime. Originally from Central America (where it blooms almost all year round), this tropical plant has found its way into many households around the world and is now an integral part of Christmas decorations. With its bright red, cream, pink or other coloured bracts, it creates a festive atmosphere for months. With proper care, a poinsettia will not only look beautiful during the festive season but can bloom again year after year – as a specimen plant or in Christmas arrangements.

Poinsettias bloom in winter in our part of the world. AS they are short-day plants, for them to bloom, they shouldn’t receive more than 10 to 12 hours of light per day.

The dormant phase usually begins early in the year – after the poinsettia has finished flowering and dropped its colorful bracts – and ends in April, when the plant begins to grow again.

The ideal compost should be free-draining to avoid waterlogging. A slightly acidic to neutral pH value is best (pH 5.5 to 6.5).

Cactus compost is perfect as it offers the necessary drainage. You can also mix normal potting compost with aggregates such as sand, perlite or vermiculite to improve drainage. Professional growers plant their plants in specialist poinsettia compost, but this isn’t readily available in shops.

To do this in our part of the world you have to introduce a darkening phase. We describe exactly how this works step by step in the section Darkening poinsettias: The trick for coloured bracts.

The first visible sign is a slight discoloration of the upper leaves (bracts). They begin to change colour from green to pink, red or another colour. In the centre of the plant, between the changing bracts, small buds form. These are the actual flowers of the poinsettia. The poinsettia will now grow more slowly as its energy is going into forming flowers.

Standard poinsettias are not winter hardy, so in the UK they should only be kept outdoors in the summer in a sheltered place away from direct sunlight. In autumn they must be brought indoors as they don’t like temperatures below 12°C.

Standard poinsettias are not winter hardy, so in the UK they should only be kept outdoors in the summer in a sheltered place away from direct sunlight. In autumn they must be brought indoors as they don’t like temperatures below 12°C.

Poinsettias belong to the spurge family. All plants in this genus contain a white milky sap that comes out when parts of the plant are damaged. This liquid usually contains poisonous substances. The wild form of the poinsettia also produces this.

In modern poinsettia breeding, these substances can no longer be detected in the sap, so poinsettias are generally harmless to humans, but they are not edible.

It’s not clear whether it’s harmful if animals such as cats, dogs or birds eat these plants, so make sure animals don’t nibble on them.

Touching the sap can cause allergic reactions in people with sensitive skin, so wearing gloves when tending them is recommended. Those allergic to latex can also react to the sap and should avoid direct contact with it.

A leaf node is the area on the stem of a plant where leaves or side shoots attach. These nodes contain important growth cells that ensure the formation of new shoots and leaves. When pruning plants such as poinsettias, the cut is often made just above a leaf node to encourage the growth of new shoots.

The actual flowers of the poinsettia are located in the middle of the coloured bracts. They are small, greenish-yellow and rather inconspicuous. These flowers are located in the cyathium, a special flower structure that is typical of plants of the genus Euphorbia, to which the poinsettia (bot. Euphorbia pulcherrima) belongs.

Bracts are special leaves that are different in colour from normal green leaves and are often mistaken for flowers. In the case of poinsettias, it is the striking red, white or pink bracts that make the plant look so festive. They originally served to draw insects’ attention to the small, inconspicuous, flowers.

Induction is the moment when the plant moves from the growth phase to the flowering phase. Both the plant’s internal clock and environmental influences play a role. In short-day plants such as poinsettias, flower induction is closely linked to the photoperiodic reaction. In poinsettias, it can be artificially induced by controlling the amount of light the plants receive.

A short-day plant is one that only produces flowers when the daily light phase is shorter than 12 hours. This means poinsettias only begin to develop their colourful, often red bracts when they experience longer periods of darkness over several weeks – in the UK, this is in autumn, when the days get shorter. In addition to the poinsettia, the Crown-of-Thorns (Euphorbia Milii), African violet (Saintpaulia) and Christmas cactus (Schlumbergera) are also short-day plants.

Photoperiodism refers to the biological response of plants to the length of day and night. Some plants, such as poinsettias, respond to the length of darkness to control their flowering time. They require a certain number of hours of darkness per day to develop their flowers or coloured bracts – these plants are called ‘short-day plants’.

Waterlogging occurs when excess water in the pot or drip tray can’t drain away and the roots of the plant are permanently submerged in water. This hinders the oxygen exchange at the roots, which leads to root rot – the roots ‘suffocate’. This can be fatal for plants such as the poinsettia, which are sensitive to too much moisture.

Perlite
Perlite is a volcanic rock that’s formed by intense heating. Growers use it as a soil conditioner to improve drainage and aeration of the soil. Perlite doesn’t retain moisture, so the roots remain well aerated and the soil doesn’t become too wet. Ideal for plants that are sensitive to waterlogging, such as poinsettias.

Vermiculite
Vermiculite is a mineral that’s used to improve soil in a similar way to perlite. However, unlike perlite, vermiculite retains moisture and nutrients, which keeps the soil moist for longer. It provides a good balance between water absorption and aeration and is often used in potting and seedling composts.

That’s it! This should prepare you for all possible challenges when looking after for your poinsettia over the summer. With the right care, there’s a good chance it will accompany you not only this winter, but also in the winters to come.

Want to know more about the history of the poinsettia and discover its many varieties? Browse this fascinating facts blog! Our deco blog has lots of ideas for creative decorations and crafts with poinsettias.

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