By: Liz Baessler
Poinsettias are famous for their flower-like bracts that turn bright red in the winter time and earn them a place as an extremely popular Christmas plant. They can be stunning when they’re healthy, but a poinsettia with yellow leaves is both unhealthy and decidedly not festive. Keep reading to learn what might lead to a poinsettia getting yellow leaves and how to treat yellow leaves on poinsettia plants.
Poinsettia leaves turning yellow can be caused by quite a few things, but the most likely source of the problem is water. So are yellow leaves on poinsettia caused by too much or too little water? Unfortunately, it’s both.
Whether your poinsettia is parched or its roots are waterlogged, it’s going to respond with yellow, dropping leaves. You should always keep the soil in your poinsettia’s pot moist. Don’t let it dry out, but don’t water until the soil is sopping wet either. Try to keep your soil so that it is always slightly damp to the touch, and the pot has just a little extra weight to it when you pick it up.
When you’re dealing with a poinsettia with yellow leaves, over or under watering are the most likely culprits simply because they’re so easy to get wrong. If you think your plant has the right amount of water, though, there are some other possible causes.
Your poinsettia with yellow leaves could be caused by a mineral deficiency – a lack of magnesium or molybdenum could turn leaves yellow. By the same token, over fertilization can burn the leaves, yellowing them as well.
Root rot could also be the cause. If you think you have root rot, apply fungicide. Repotting your poinsettia plant may also help. You can prevent the likelihood of root rot by always using new, sterile potting soil.
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Kousa dogwood trees (Cornus kousa) are superstars in the home garden, with visually lush purple to red fall foliage, showy creamy white flowers and resistance to a variety of destructive diseases that affect many dogwoods. While these deciduous trees often escape problems such as dogwood anthracnose and powdery mildew, they are not immune to health issues. Pay close attention to kousa dogwoods and put control methods into effect quickly at the first sign of a problem.
If your marijuana leaves are turning yellow, don’t panic! This is just your plants’ way of telling you something is wrong. It is up to you to determine what that is so you can treat the problem without making it worse.
The first thing you should do when cannabis leaves start to turn yellow is to measure the pH of your grow medium (soil, water, rice hulls, expanded clay, etc.). That’s because an improper pH balance – whether too high or too low – can actually block nutrient absorption.
After measuring and adjusting pH, take a look at your watering schedule. The most common cause of yellow leaves is either over- or under-watering. Plants that are over-watered will have leaves that seem swollen and droopy while under-watered plants (though much less common) will be thin and frail. Poor drainage can also contribute to overwatering so always grow your cannabis in pots with drain holes.
If the yellowing occurs primarily at the base of the plant, the issue is likely a nutrient deficiency. The most common nutrient deficiency in cannabis is nitrogen, though note that excessive nitrogen can also cause yellowing (plus curled, claw-like leaves). If the problem is caused by a deficiency, slowly increase the concentration of your cannabis-specific fertilizer until new growth appears. If the yellowing is caused by excessive nutrients, flush the root system with pure water then add a half-dose of your fertilizer instead. Magnesium deficiency, characterized by a yellowing around the leave’s green veins, is most commonly caused by an improper pH balance. Use magnesium supplements to correct this issue
Iron deficiency can also cause yellow leaves, though this occurs on new growth only (old leaves remain bright green). Iron deficiencies are also caused by improper pH and can be remedied with iron-fortified fertilizers. When iron is given to deficient plants, the leaves should start to turn green beginning along the edges until the whole leaf is bright green.
If you notice yellowing toward the top of the plant (specifically, nearest the light source), your plants are likely suffering from light burn. Light burn can happen in temperature-controlled environments as easily as those in high-heat if the leaves get too close to the lights. We liken this to getting a sunburn on the ski slopes.
Temperatures outside of the ideal range of 70 to 80 degrees Fahrenheit also risk discoloration and curl leaves. These oddities are most common in leaves toward the top of the plant and can easily be remedied with a fan (if too hot) or root insulation (if too cold). We also recommend growing plants off a cold cement or tile floor use a milk crate or stool to raise them off the ground when necessary.
If your yellow leaves come with spots or bite marks, they’re probably infested with pests. Though you can often see the infestation, this is not always the case – a tell-tail sign (aside from the remnants of the buffet) is a plant that lacks vigor in addition to other symptoms associated with things like overwatering or poor air circulation.
Unfortunately, pests are perhaps the hardest condition to correct, so it’s best to avoid try and avoid them all together. To start, never bring plants or clones from an outside grow into your sanitary grow space and try to avoid entering your grow space directly from the outdoors. Always wash hands, cover your hair and avoid letting pets anywhere near your grow space.
Fungus gnats, which live in wet soil and feed off roots, are the most common pest in cannabis gardens. The best way to rid your garden of fungus gnats is to restrict watering until absolutely necessary (this prevents the gnats from laying eggs in the soil). A general best practice is to only water your plants when the top inch of soil is dry.
Growing your own marijuana is very rewarding, but it can be really nerve wracking, too, especially when those bright green leaves start turning a worrisome yellow. If your cannabis leaves are turning yellow, use these steps to stop the yellowing before it’s too late.
What do you do to fix yellow cannabis leaves? Share your feedback in the comments below.
Abby is a writer and founder of Cannabis Content, a marketplace designed to connect cannabis writers and creatives with businesses in the industry. She has been a professional cannabis writer since 2014 and regularly contributes to publications such as PotGuide and M&F Talent. She is also the Content Director at Fortuna Hemp, America’s leading feminized hemp seed bank. Follow Abby on Facebook, Twitter, and Linkedin.
There are many reasons a poinsettia could be losing its leaves. Photo: http://www.gardeningwithsurgicalprecision.com
Here’s a common Christmas plant problem: poinsettias (Euphorbia pulcherrima) whose lower leaves turn yellow and drop off, often within days of purchase. Yet the poinsettia has the reputation of being able to “hold on” for at least a month or two if given reasonable care. Why then is yours losing its leaves so soon after you bought it?
A Symptom of Stress
Leaf drop in the poinsettia is a symptom of stress. The plant isn’t happy and shows its displeasure by dropping leaves. Usually, it’s the lower leaves that are sacrificed first. They turn yellow and off they fall. Then, if the cause of stress isn’t corrected, the leaf drop will gradually progress up the plant until it appears nearly naked, with only the colored bracts and a few green leaves on the top.
So much for the symptoms, but what causes this stress? Here are 10 possibilities.
Problem #1: The Plant Was Exposed to Cold
Cold can cause leaf drop. Ill.: http://www.kisscc0.com & clipart-library.com
In most areas, Christmas is the coldest time of the year, so when you purchase a poinsettia, just bringing it back from the store can stress it severely. Even a few minutes of exposure to temperatures below 10 °C can cause leaves or bracts to fall off.
Solution: Always insist the salesperson carefully bag your poinsettia before you leave the store. And don’t place a poinsettia on a frozen seat in an icy car, but instead heat your car in advance.
Problem #2: It Has Been Kept Wrapped Too Long
Don’t leave your poinsettia wrapped too long. Photo: Alibaba.com
Poinsettias give off a toxic gas called ethylene. In the open, this gas diffuses rapidly and causes no harm. But if you keep your plant inside a closed plant sleeve for a few days, the concentration increases and leaves and bracts will begin to fall.
Solution: Remove the poinsettia from its wrapping as soon as you get home. If you intend to wrap your poinsettia as a gift, do so just before you leave to give it, not days ahead.
Problem #3: Carbon Monoxide Exposure
Rapid leaf loss could mean the presence of carbon monoxide. Ill.: http://www.hospitalitynet.org
The poinsettia is the canary in the coalmine of houseplants when it comes to carbon monoxide (CO), an odorless, tasteless, toxic gas, reacting well before humans show the slightest symptom. If your plant starts to lose its leaves practically as soon as you bring it into your home, the level of carbon monoxide in your home may be too high.
Solution: Check the level of carbon monoxide in your home using a carbon monoxide alarm. If it goes off, leave your home immediately and call emergency services.
Problem #4: The Air Is Too Dry
Poinsettias tolerate dry air relatively well, especially compared to so many other indoor plants, but there is a limit. When the air is exceptionally dry, remaining at less than 30% almost all the time, the leaves begin to drop off, often browning at the margins or at the tip beforehand. If the soil dries out very quickly after a good watering, say in only 2 or 3 days, that’s another symptom that the air is very dry.
Solution: Increase the humidity using a humidifier or place the plant on a humidity tray.
Problem #5: Insufficient water
Oops! You forgot to water, didn’t you? Photo: mondaymorningflowers.wordpress.com
When you find your poinsettia wilting, with all its leaves and bracts hanging limply like lettuce in the sun and its soil is dry to the touch, it’s pretty obvious that it lacked water. Usually the foliage will recover its turgidity after a thorough watering, but … a few days later, the lower leaves begin to turn yellow and drop off. Do note that this leaf loss due to a lack of water is not always your fault. The stress may have occurred in the store before you bought the plant. Note that box stores and supermarkets, especially, are not known for their proper maintenance of the plants they sell.
Solution: Touch the soil of any poinsettia you’re thinking of buying in the store. If it’s dry, don’t buy it. Purchase only a poinsettia that looks healthy, with green leaves right to its base, and whose potting mix feels at least a bit damp.
It’s too late? The soil of your plant is bone dry and it has already wilted? Water it thoroughly and without delay to at least save it. Once it has recovered, learn how to water your poinsettia properly so it won’t wilt again. Whenever the soil is dry to the touch, water deeply, enough so that the excess water flows into the saucer. Just to make sure the plant really did get enough water, even let the plant soak in the excess water for 15 to 20 minutes, then empty the saucer.
It’s important to understand that you can’t force a poinsettia to adapt to a specific watering schedule. The typical “I water once a week” method can never be counted on. At some point, you’ll almost always end up under- or overwatering the plant, depending on the conditions. This is because the same plant may well find a weekly watering quite adequate during a moderately sunny week when it’s fairly cool indoors, but then can wilt terribly the following week because it’s suddenly extremely sunny and the window ledge became extra hot. And yet another week later, when the weather is exceptionally gray and cool, the potting mix might still be almost soaking wet a full week after the plant was watered. If watering needs vary so widely, it’s because indoor conditions change constantly.
Ideally, you should check the soil every 3 or 4 days, pressing your index finger into the soil up to the 2nd joint: if the soil is dry, water well. If it is still wet, come back 3 or 4 days later and check again, watering only when needed. That is the key to successful watering almost any plant, not just the poinsettia! You may well find that the same plant can sometimes need watering after only 4 days under some circumstances and, at other times, only after 10 or 12 days.
Finally, note that mini-poinsettias, which are actually young cuttings grown in small pots and forced for early flowering, are especially susceptible to underwatering. Their tiny rootballs dry out quickly and it’s best to check their growing mix every two days.
Problem #6: The Plant Was Overwatered
Root rot due to overwatering. Photo: http://www.pthorticulture.com
It seems illogical, but a poinsettia will react the same way when it’s overwatered as when it’s underwatered: the foliage wilts and drops off. Why? If the potting mix remains overly wet for a long time, the roots begin to rot due to the lack of oxygen and when this happens, disease organisms attack the roots, killing a few of them, then more and more. Therefore the foliage wilts, despite the abundance of water, since the roots are no longer there to absorb it.
Solution: Saving a poinsettia whose roots have begun to rot is not easy. That’s because rot is a disease (Pythium, Rhizoctonia or other) that spreads from dead or dying roots to living ones. It is probably best to simply replace any poinsettia suffering from rot.
Problem #7: It’s too hot or too cold in the room where you keep your poinsettia.
And an unhappy poinsettia will start to lose its leaves.
Solution: The ideal temperature for a poinsettia is between 60 and 75˚C (15 and 24˚C). If it is colder or warmer than that, especially over a long period, it’s best to move it to a spot more suitable to its needs.
Problem #8: Lack of Light
After 3 months in a dark corner, this poinsettia has given up the struggle. Photo: oneawkwardyear.wordpress.com
This problem is usually seen only in the long run, because a poinsettia can usually take 7 or 8 weeks in the shade before reacting negatively and starting to lose its lower leaves. That’s why you can use a poinsettia almost anywhere in the home over the holidays, even in a dark corner. But if you want your poinsettia to remain in good condition until spring, it will need good light.
Solution: After Christmas, place your poinsettia in a spot where it will receive adequate lighting, including at least a few hours of sun a day, such as near a sunny window.
Problem #9: Insect infestation
Whiteflies under a poinsettia leaf. Photo: M.J. Raupp, bugoftheweek.com
Whiteflies love poinsettias, piercing the leaves to lap up their sap, thus causing their foliage to slowly turn yellow and then drop off. Spider mites, mealybugs and scale are other sap-sucking insects that also sometimes infest poinsettias and give similar results.
Solution: Usually, the plant was already infested in the store, so the first solution is, of course, to carefully inspect the plant before you buy it. Look especially under the leaves and at leaf axils, as that is where pests often hide. If you see signs of insects, don’t buy the plant… or any plant in that store, as insects do get around. If you find insects on a plant after you bought it, different treatments, including sprays with insecticidal soap, neem oil, horticultural oil and rubbing alcohol, can be used to control the invaders. Read the label carefully, as poinsettias are sensitive to many sprays. And keep the plant isolated from your other houseplants so the infestation won’t spread.
Problem #10: Aging Leaves
It is perfectly normal for a poinsettia to lose a leaf or two from time to time. That’s its way of getting rid of older, less functional leaves.
Solution: Just pick up the dead leaves!
Poinsettias Really Aren’t That Difficult
I hope the above list of problems and solutions didn’t scare you off, because, in fact, the majority of people who water their poinsettia correctly have no problem keeping it in good condition for at least a month or two. And those who, in addition, make sure it receives adequate light can even expect it to hold on to its beautiful bracts until May or even June for a full 6 months of beauty!
As for how to get your poinsettia to bloom again, an entirely different subject, here are some tips.
No, the poinsettia isn’t difficult to maintain, but like any plant, it still needs at least a bit of basic care to be happy. Give it what it needs and your poinsettia will repay you in spades!
Adapted from an article originally published on December 10, 2015