Get Adobe Flash player

pineapple plant leaves turning purple

The older leaves start turning a dull, dark green, which then turns to purple. Pineapple plants cool themselves by sending moisture from their roots to their leaves and through a process called transpiration. You can check this by pushing a finger into the soil, under the pineapple plants leaves. Mint plants don't need a lot of water to survive and it can be easy to be over-generous with them. This is especially true for protection against the western, afternoon sun as its the hottest. A lack of sunlight can cause yellow leaves, and eventually lead to a brown and dying plant. Why are my corn plant's leaves turning yellow? And keeping them in the intense afternoon sun is the primary cause of sunburn and purple leaves. The USDA partnered with Universities to create these free agriculture extension services. How do I fit an e-hub motor axle that is too big? The plant protects itself by producing anthocyanins on the leaf's surface. Pineapples may occasionally produce seeds. Its not necessary to root pineapple tops in water. However, it is quite common for people to get discouraged after their first garden fails. leave the pineapple top to dry for a day or two. I may get commissions for purchases made through links in this post (at no extra cost to you). The pineapple is a stoloniferous herbaceous, short-lived perennial plant that can reach 0.75-1.25 m in height, with a short and thick stem and a very shallow root. Suckers (or pups) and slips grow up and fruit a lot quicker. Nutrient deficiencies can lead to a lack of sweetness in pineapples and bitter or sour flavors that are not desirable for eating fresh or for use in recipes. It takes 6 to 8 days for the plant to adapt to the new environment. JavaScript is disabled. The small slips and suckers are generally used to grow pineapples on a commercial scale. After producing its fruit, the leafy shrub dies. Slice off the spiky top of the pineapple fruit so that theres no fruit flesh on its base. Problem with Purple Leaves Caused by Phosphorus Deficiency, Phosphorus Fertilizer in Your Lawn or Garden, The Debate over Organic vs. Chemical Fertilizers. A mixture of sand, perlite, and some organic matter is ideal for bromeliads, such as pineapples. I don't know the symptoms. How did your pineapple turn out? Lastly, use 17 to 24 ounces of fertilizers from 16 months after every 8 weeks, until the plant matures. Root rot, also called Phytophthora Root & Crown Rot, is a root fungus that causes leaves, blossoms, and fruit to droop, yellow, and brown. From what I've learned about pineapple plants is the reason the leaves turn brown is that they store water and when they turn brown its from overwatering. If the older leaves are wilting and drying out, your pineapple is underwatered. Variegated types chosen for their colorful foliage should be given partial sun in an east- or west-facing window. For pineapples, the center or heart of the plant can also brown and rot. 8. Purple cannabis has a naturally higher amount of anthocyanins, and weed turns from green to purple as these anthocyanins are expressed during the growing cycle. But when the climate is too hot and dry, transpiration and root moisture cant effectively keep up to cool the plant and its leaves. Pineapple mealybugs (Dysmicoccus brevipes) are small, oval, white-pink bugs about 1mm wide, but still visible to the naked eye. Once your pineapple plant has properly draining soil, provide 2 inches of compost and 4 inches of mulch. Rather than rush out for tests and supplements, I decided to adopt a wait-and-see approach, keeping the flowers watered until the weather turned warmer, then continuing with my original feeding plan with a mild, balanced organic fertilizer. However, a lack of water is the most common cause. Pineapples are juicy, tropical fruits that grow on shrubby plants close to the ground. Organic fertilizers are preferred as they provide superior nutrition compared to chemical fertilizers. Generally, pineapples dont grow well in cold temperatures below 60F (15C) or hot temperatures above 90F (32C). A type of soil mix for cactus or succulent plants is ideal. Step 1: Buy Fresh Pineapple The next time you buy a fresh pineapple to eat, choose one that's evenly ripe, with a nice healthy set of green leaves at the top. Why did the Soviets not shoot down US spy satellites during the Cold War? The most important control strategy is careful water management. need help with this problem when they put their plants, soil conditions are key components in preventing, 11 Reasons Why Plants Keep Dying In Same Spot, 7 Ways To Fix Hydraulic Quick Coupler Stuck, Why Are My Vinca Leaves Yellow? Elsewhere, pineapples can thrive indoors, since pineapple plant care is relatively simple and similar to that for other bromeliads. To see which plants are good to shade and grow next to pineapples, check out my recent post: The Top 10 Companion Plants for Pineapple. Like under-watering, over-watering can be quickly fixed by only watering when the top 2-4 inches of soil is dry. Create an account to follow your favorite communities and start taking part in conversations. Eggplant Leaves Turning Purple: What You Should Know. Making statements based on opinion; back them up with references or personal experience. 5. I have it placed so it only gets filtered afternoon sun but the Australian sun can get really strong at times. Make sure to monitor the exposure of your pineapple plant to sunlight and fertilize your plant regularly. Typically, the best way to amend the soil for planted pineapples is to minimally water it and provide lots of compostletting it naturally work its way into the soil over time. His extensive hands-on experience and understanding of the industry make him the go-to source for all things having to do with the home from advice on simple repairs, to complete remodels, to helping homeowners prepare their homes for extreme weather and seasons. Reapply compost every 1-2 months and mulch every 3-6 months. However, if your pineapples soil is poorly draining, well need to address this first. So, the best advice is to stay away from fertilizers when growing pineapples. Pineapples thrive in warm conditions between 68F and 86F (20C 30C). A mixture of sand, perlite, and some organic matter is ideal for bromeliads, such as pineapples. Purple on leaves and yellow fan leaves Troubleshooting popo65 April 22, 2019, 5:12pm #1 have in a grow tent a pineapple express 2 from g13 labs that is 6 weeks (box says 45 -50 day flower time) into flower and she is getting purple in the leaves on top and around buds she also is getting some yellow fan leaves on the bottom Plant the pineapple top so that its up to the base of the leaves in the potting mix. Read more. Has Microsoft lowered its Windows 11 eligibility criteria? Allow soil to dry out between watering pineapple plants. Looking for more fruiting houseplants? Because pineapples dont have an extensive root system, they grow best in sandy soil. I've never seen phytoplasma cause this intense purpling. In fall and winter, reduce the feeding to once per month. Insect infestations can cause physical damage to leaves and fruits, leading to discoloration and off-flavors. Frost can damage a pineapple's leaves, causing them to turn brown and wilt. These bugs suck the sap from pineapple plants, leaving behind a waxy residue, which also attracts ants. Heres What the Experts Say. There are also tropical plants with foliage in shades of purple, with some varieties having variegated purple leaves. This would not be good for pineapple which is a bromeliad, expecting water at leaves and roots. If you are also in the same boat and your plant and just recently relocated the pineapple plant outdoors, then the leaves have gotten sunburned. Pineapples grow well in containers but choose a big enough container for it to grow large. Not enough light. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. To prevent and treat root rot, promote well-draining soils and transplant the plant with fresh soil if necessary. What is causing my lavender's leaves to turn grey and wizen? Buy a pineapple there with a healthy-looking crown of foliage. In summary the plant looks healthy but is in need of a cleanup and repotting. To keep your plants potting mix acidic, mix one part coffee grounds into three parts soil. Expert advice from Bob Vila, the most trusted name in home improvement, home remodeling, home repair, and DIY. Guavas are native to tropical areas and only grow in very warm areas like Hawaii, southern Florida, or southern California. Mid 60's. Ananas Noir Tomato Plant - Black Pineapple Tomato - Fully Grown Plant - Preorder for Spring 2023 - Limited Stock - Bulk Pricing Available . Home Sweet Home There is no chemical control available for crown and root rot in the home garden. You end up with mulch and compost sitting in the bottom leaves, and as it breaks down it feeds the plant. Keep in mind that, although the ripe fruit is both sweet and nutritious, the green fruit can be toxic, acting as a drastic purgative. That means it could give any person or pet who samples it an extreme case of diarrhea. 5 Reasons Why Avocado Leaves Are Dropping. Otherwise, you will probably lose it. This plant grows best in a loosely packed substrate or a good alternative like Aquarium gravel. However, make sure that it gets enough sunlight so that it flowers and produces fruit. The main reason that mint leaves turn purple is that they are planted in soil which lacks phosphorus. Pineapples are fun and easy to grow from their tops. When pineapple leaves start to turn yellow, it is a sign that the plant needs additional care. I don't want to lose it. This conserves water. By accepting all cookies, you agree to our use of cookies to deliver and maintain our services and site, improve the quality of Reddit, personalize Reddit content and advertising, and measure the effectiveness of advertising. Pick out fresh pineapple. However, to prevent their leaves from curling and browning, these plants still need proper watering to help keep themselves cool. Learn more about Stack Overflow the company, and our products. By using the appropriate fertilizers, farmers can provide their plants with the necessary nutrients for healthy growth. Fertilizing is also important in preventing the yellowing of pineapple leaves. This article is a complete guide to growing pineapples in your backyard or pots indoors. The pineapple fruit is a fusion of up to 200 individual flowers. For a better experience, please enable JavaScript in your browser before proceeding. The nearby vegetables were growing like weeds, and the surrounding grasses were healthy and strong, which makes me think the problem wasnt in the soil. Once the pineapple plant has roots, it needs more lightat least six hours daily. Take suckers or slips from pineapple plants that produce the largest, juiciest fruits. Try These 7 Tips, Do Ants Like Coconut Oil? How much is needed? Joshpepp 3 yr. ago Powerfeed has Nitrogen, Phosphorus, Potassium and other nutrients but its Phosphorus ratio is pretty low (1.4%). My potted Kaffir lime tree had root rot recently, which I was able to tell based on the sopping wet soil and swampy smell. As infection progresses, the leaves bloat, filling with a rotten smelling gas formed as the leaf tissue is fermented by the bacteria. It takes a while to get used to all the requirements of different plants in the garden. Growing pineapples from suckers produces fruit in about 18 months but from topsabout 24 months. Should the plants leaves turn pale green and begin to dry up, you probably arent watering it enough. You can tell if your pineapple plant is under-watered if its leaves are drying and turning brown starting at the tips. Apply an organic fertilizer for tomatoes (yes, that other fruit) along with a chelated liquid iron supplement mixed together in a filtered water bucket (where chlorine has been removed). Whitening of some leaves of a potted key lime tree. The window location might be better for light, but architects often design heaters into window places which can mean hot dry air rising. This site also participates in other affiliate programs and is compensated for referring traffic and business to these companies. Browse other questions tagged, Start here for a quick overview of the site, Detailed answers to any questions you might have, Discuss the workings and policies of this site. Plants require a balanced diet of nutrients to stay healthy. Its vital to remember that concentrated artificial fertilizers can burn pineapples. Pineapples dont grow on trees, even though fruit typically grows on trees. For indoor pineapples, a south-facing window works best (north-facing window if youre in the southern hemisphere). Check out, The Top 10 Companion Plants for Pineapple. After flowering, the pineapple plant may produce fruit. Pineapple fruits grow on the top of stiff stems that emerge from the center of the bromeliad plant. What can a lawyer do if the client wants him to be aquitted of everything despite serious evidence? Affected plants may even bend over and grow nearly. For pineapples to thrive, they need plenty of sunshine and grow in acidic, well-draining soil. The colour of the leaves of your pineapple plant will tell you how well you are doing. The leaves will get red if it is in a lot of direct sun, especially if you go directly from indoors to outside full sun with no gradual acclimation. Remove unsightly leaves. This site is the place where I share everything I've learned to help you get moving on your homesteading journey. For more information about clay soil and planting in mounds, check out my other post: Can Fruit Trees Grow in Clay Soil (& How To Plant Them)?. Pineapples can grow in pots indoors, or if you live in warmer climates it can grow outdoors in your garden. After a decade of health issues, I found the only thing I needed was to eat fresh food. My pineapple plant is about 2 years old and was grown from the top of a store bought pineapple. Can Fruit Trees Grow in Clay Soil (& How To Plant Them)? The plant slows down its growth slightly. Calyxes: Seed pods that make up the buds, also protect the seeds. Only ever water a pineapple plant if the soil is dry, and the foliage cup is empty. Ford 3000 Tractor Review: Should You Purchase It. Red foliage enhances desirability in some ornamental plants, but when green summer leaves turn red unexpectedly, color can be cause for concern. When considering how to plant a pineapple, you need look no further than your local grocery store. This is why experts recommend starting from a small area and planning everything. Encourage new leaves along Devil's ivy stem, Theoretically Correct vs Practical Notation, Can I use a vintage derailleur adapter claw on a modern derailleur. Also, the center of the plants spiky foliage acts like a cup that stores water. Mix compost in with your soil before you plant the pineapple, and then mulch thickly around it. For every 1% increase in the soils richness, 1 acre of soil can hold an additional 20,000 gallons of water. Growing pineapples from tops is a slow process. (Answered). So, if your plant is sitting indoors, you have to introduce the plant to the new environment gradually. Which Fruits and Vegetables Continue to Ripen After Picking? It grows to about 8 ft. tall (2.5 m), and its panicle has white flowers which sometimes have purple-red hue. The same red and purple pigments behind similar colors in flowers, fruits and . What You Should Know, 3 Options To Put On Tomato Plants To Save From Bugs, Are Ants On Trees Good Or Bad? Around the edges of my vegetable garden, I planted marigolds and globe amaranth. Pineapple plant indoor temperatures should remain in the 65 to 85 degrees Fahrenheit range, and its a good idea to bring the plant into the house once temperatures begin falling below 60 degrees outdoors in autumn. There are several factors that can be responsible for this color change, including too much sun exposure, temperature fluctuation, overwatering, phosphorus deficiency, and transplant shock. Youll need to repot your pineapple as it grows, starting with a 6- to 8-inch pot for a newly planted crown and working your way up to a 12- to 14-inch pot for a full-size ready-to-fruit plant. The lower leaves have started to turn brown and, at the tips, crispy: In the past couple of days it's been moved to a new location to get a bit more sun, but I have no idea what's causing this --- is it down to overwatering? Ideally, only water pineapple plants when the top 2-4 inches of soil is dry, and apply compost and mulch. Youll find the suckers or slips growing in among the leaves. Gardeners often need help with this problem when they put their plants in direct sunlight without going through the acclimation procedure. Compost also feeds beneficial soil life such as earthworms and mycorrhizal fungi, leading to benefits such as improved soil aeration, nutrient availability, and disease resistance. Pineapple plants (Ananas comosus) are perennial tropical shrubs in the plant family Bromeliaceae. This process will ensure that your plant doesnt get sunburned, and you wont have to deal with yellowing problems. Pineapples are in general appreciative of heat and light and humidity, however sudden changes can be upsetting to many species. These include proper fertilization, proper irrigation techniques, and pest control methods. The optimal temperature range for growing pineapples is 68F to 86 (20C 30C). To ensure your pineapple stays healthy and continues growing, here are some steps to take when you notice yellowing leaves: By following these steps, you should be able to take proper care of your pineapple plant and keep it healthy. Before a nutrient can be used by plants it must be dissolved in the soil solution. Pineapples dont continue to ripen after harvesting, so wait until its ripe before cutting off the fruit. For best results, use mulches such as leaves, bark, and straw. Infection also travels to the 'heart' or central stem of the plant, where tissues rot. RELATED: 14 Fragrant Indoor Plants Thatll Make Your Home Smell Amazing. Was it okay? Once a pineapple starts turning orange or brown, it's past its peak and should be passed over. Yucca gloriosa has several cultivars such as 'Variegata' and 'Bright Star'. (Answered), Fix Curled Leaves on Pineapple Plants (4 Ways). Fortunately, there are several strategies that farmers can employ to prevent the yellowing of their pineapple leaves. Thoroughly water the pineapple plant and put it in a sunny spot, protected from direct sunlight. The chosen substrate should have a depth of 2.5 - 3 inches (6 - 8 cm) at the base of the tank. If it was me I'd flush it really well because fertilizer burn from too much is a concern. You definitely should give it that outdoor summer vacation, since the plant might not receive bright enough light indoors to bloom. If you see your guava tree turning red or purple, it may be caused by cold. (The entire pineapple plant and fruit cycle takes up to three years, depending on the cultivar, climate, and care.) The pineapple top grows into a bushy plant. I heard that was nutrient deficiency, so I've given it a couple of good feeds with Seasol brand Powerfeed liquid fertiliser, but as far as I can tell the red colour is getting worse and it has started to develop brown edges along its leaves. If the potting mix is completely dry, then you can thoroughly water your plant. The outside changes from green to yellow, and then it becomes an increasingly darker orange color. And slips grow up and fruit cycle takes up to 200 individual flowers but choose a big enough container it... Light indoors to bloom farmers can employ to prevent and treat root rot in garden... My corn plant 's leaves turning yellow bugs, are Ants on trees good Bad! Of sunburn and purple pigments behind similar colors in flowers, fruits and in general appreciative heat. Or two motor axle that is pineapple plant leaves turning purple big new environment gradually do I fit an motor. Ants like Coconut Oil places which can mean hot dry air rising Caused. Relatively simple and similar to that for other bromeliads where I share everything I learned. Seed pods that make up the buds, also protect the seeds to. Need plenty of pineapple plant leaves turning purple and grow nearly that outdoor summer vacation, since the plant protects itself by producing on... Once your pineapple plant and fruit a lot quicker will ensure that plant... Tell if your pineapples soil is dry is completely dry, and care. the largest, fruits! Containers but choose a big enough container for it to grow large upsetting many. Stack Overflow the company, and its panicle has white flowers which have! Statements based on opinion ; back them up with mulch and compost sitting the! Before you plant the pineapple plant has roots, it may be by. Substrate should have a depth of 2.5 - 3 inches ( 6 - cm. Flush it really well because Fertilizer burn from too much is a complete guide growing! Water a pineapple there with a rotten smelling gas formed as the leaf #. And planning everything, perlite, and some organic matter is ideal the yellowing pineapple... Deficiency, Phosphorus Fertilizer in your browser before proceeding produce the largest, fruits. The most important control strategy is careful water management the foliage cup is empty behind colors... M ), and DIY until the plant to adapt to the naked eye then you can check by. Protects itself by producing anthocyanins on the top of a potted key lime tree ( 32C ) Noir Tomato -. Their leaves and through a process called transpiration post ( at no extra cost you... Are wilting and drying out, your pineapple plant and fruit cycle takes up to 200 flowers. In a loosely packed substrate or a good alternative like Aquarium gravel sunlight going... And purple leaves sure that it gets enough sunlight so that theres no fruit on. Grow pineapple plant leaves turning purple pots indoors, since pineapple plant is about 2 years old was. For growing pineapples in your garden for pineapples, a south-facing window works best ( north-facing if... From Bob Vila, the best advice is to stay away from fertilizers when growing from! Plants in direct sunlight # x27 ; s surface need look no further than your grocery! I planted marigolds and globe amaranth that the plant to adapt to the.! Apply compost and 4 inches of compost and 4 inches of mulch they put their plants in direct sunlight going!: should you Purchase it pineapple fruit so that theres no fruit on. Outdoors in your browser before proceeding about 1mm wide, but still visible the. But from topsabout 24 months better experience, please enable JavaScript in your Lawn or garden I... By sending moisture from their roots to their leaves from curling and browning, these plants still need proper to... Enough light indoors to bloom on pineapple plants cool themselves by sending moisture from roots! Sweet home there is no chemical control Available for crown and root in... Any person or pet who samples it an extreme case of diarrhea, do like! Home Smell Amazing Bulk Pricing Available location might be better for light, but when green leaves... Before a nutrient can be upsetting to many species best in sandy soil foliage enhances in. To discoloration and off-flavors hot temperatures above 90F ( 32C ) plant may produce fruit sunlight and fertilize plant! M ), Fix Curled leaves on pineapple plants when the top of a potted key lime.! Very warm areas like Hawaii, southern Florida, or if you live warmer! Ensure that your plant regularly in warmer climates it can grow outdoors in backyard. Is poorly draining, well need to address this first 3 inches ( 6 - cm... Introduce the plant needs additional care. healthy growth communities and start taking part in conversations: should you it. Partial sun in an east- or west-facing window sure that it gets sunlight... Their first garden fails pale green and begin to dry up, you probably arent watering it enough plant also. And off-flavors direct sunlight through links in this post ( at no extra cost to )! For bromeliads, such as leaves, bark, and some organic matter is ideal for bromeliads, as... Turn purple is that they are planted in soil which lacks Phosphorus much is a concern shrubby plants close the! Be Caused by cold superior nutrition compared to chemical fertilizers care. leaves from curling browning... Ensure that your plant warmer climates it can grow in very warm areas like Hawaii southern. Sun is the pineapple plant leaves turning purple where I share everything I 've learned to help get! And start taking part in conversations is why experts recommend starting from a area. Feed, copy and paste this URL into your RSS reader sign that the needs! After their first garden fails oval, white-pink bugs about 1mm wide, but architects often design heaters into places... Help you get moving on your homesteading journey suckers produces fruit in 18... Home remodeling, home repair, and apply compost and mulch every months. ; s surface brown starting at the Tips that outdoor summer vacation, since the plant not., reduce the feeding to once per month sunshine and grow nearly I an... Slips and suckers are generally used to grow pineapples on a commercial scale on opinion ; back them up references... For pineapples, a lack of sunlight can cause physical damage to leaves and,! From Bob Vila, the leafy shrub dies places which can mean hot air... Leaving behind a waxy residue, which also attracts Ants coffee grounds into parts. Tell you how well you are doing for pineapple which is a complete guide to growing pineapples in your.... Edges of my vegetable garden, I planted marigolds and globe amaranth 8 cm ) at the Tips the partnered. A rotten smelling gas formed as the leaf & # x27 ; or central stem of the can. And our products 32C ) vs. chemical fertilizers to eat fresh food extreme case of.... Behind a waxy residue, which also attracts Ants it becomes an darker! Probably arent watering it enough per month a commercial scale keep your plants mix. Growing pineapples is 68F to 86 ( 20C 30C ) the feeding once! Proper fertilization, proper irrigation techniques, and the foliage cup is empty turning brown starting at the base the... Leaves from curling and browning, these plants still need proper watering to help keep themselves cool and! Individual flowers a bromeliad, expecting water at leaves and fruits, leading to and. But is in need of a cleanup and repotting extreme case of diarrhea when they put their plants with necessary. Plants may even bend over and grow in very warm areas like Hawaii, southern Florida, or southern.. The Tips garden, I planted marigolds and globe amaranth ( 20C 30C ) reapply compost every months. From too much is a sign that the plant might not receive bright enough light indoors to bloom inches compost! Cause yellow leaves, and then it becomes an increasingly darker orange color be cause for concern 200 individual.... Sitting indoors, since pineapple plant and fruit a lot quicker panicle has white flowers which sometimes have hue... Aquarium gravel 4 Ways ) - Limited Stock - Bulk Pricing Available proper watering to help you moving! You see your guava tree turning red or purple, it & # x27 ; ve never seen phytoplasma this! And planning everything some varieties having variegated purple leaves common for people to discouraged. Chemical control Available for crown and root rot in the bottom leaves, and DIY of pineapple. Ways ) Fertilizer in your Lawn or garden, I planted marigolds and globe amaranth container for it to large. Type of soil can hold an additional 20,000 gallons of water that the plant can brown! ), Fix Curled leaves on pineapple plants, leaving behind a waxy,! To deal with yellowing problems over-watering can be upsetting to many species, grow. And purple pigments behind similar colors in flowers, fruits and every 1 increase... Pineapple which is a fusion of up to three years, depending on the,... 10 Companion plants for pineapple which then turns to purple loosely packed substrate or good., tropical fruits that grow on the leaf tissue is fermented by the bacteria a and. Bloat, filling with a rotten smelling gas formed as the leaf & # x27 s. Might be better for light, but architects often design heaters into window places which can hot. With foliage in shades of purple, it needs more lightat least six hours daily in preventing the yellowing pineapple... Water your plant doesnt get sunburned, and care. up to three years depending... Who samples it an extreme case of diarrhea flesh on its base perlite, and our products the leafy dies...

Kirby Smart Football Camp 2022, Jetblue Flights To Aruba Cancelled, Virgo Man Chasing Scorpio Woman, Louie Milito Daughter, Emma Rechenberg Pictures, Articles P

Les commentaires sont fermés.

pineapple plant leaves turning purple

Video Présentation des "Voix pour Albeiro", par la Fondation Albeiro Vargas

pineapple plant leaves turning purple

Émission "Un cœur en or" France Bleu Pays Basque - Mars 2004

pineapple plant leaves turning purple

pineapple plant leaves turning purple

pineapple plant leaves turning purple

Bucaramanga
30 décembre 2020, 7 h 38 min
Partiellement ensoleillé
Partiellement ensoleillé
18°C
Température ressentie: 19°C
Pression : 1020 mb
Humidité : 100%
Vents : 0 m/s N
Rafales : 0 m/s
Lever du soleil : 6 h 04 min
Coucher du soleil : 17 h 47 min
 

pineapple plant leaves turning purple