Plant Leaves Yellowing – For Indoor, and Outdoor Plants

Introduction to Yellowing of Plant Leaves

Yellowing leaves on your plants can be caused by several conditions. Possible causes of yellowing leaves on your plants include poor drainage, damaged roots, compacted roots, high soil pH level, and nutrient deficiencies in the plant. Growing indoor plants is always a matter of patience. Indoor plant leaves turning yellow can be a sign of these out of balance or even certain nutritional or chemical influences. When you find out why leaves on plants turn yellow, you can start finding your ill plant and nurse it back to health. In this article we also discuss below topics;

  • What nutrient deficiency causes yellow leaves
  • How to fix yellow leaves on plants
  • Garden plants turning yellow
  • Can yellow leaves turn green again?
  • The bottom leaves turning yellow
  • Plant with yellow spots on green leaves
  • Reasons for houseplants leaves turning yellow
  • Should you remove yellow leaves from houseplants
  • Can yellow leaves turn green again?
  • Should you remove yellow leaves from houseplants
  • What are the reasons for leaves turn yellow and how to fix them

A Step By Step Guide to Yellowing leaves on plants

Yellowing leaves on plants may be a sign of too little or too much water or nutrients or lack of sunlight which can affect plant performance. A yellow leaf on a houseplant is unlikely to turn green colour again unless the yellowing is caused by a nutritional deficiency, which if resolved, could cause the green colour to return. Usually though, say goodbye to the green.

Causes for Yellowing Leaves on Plants

Different causes for yellowing leaves on houseplants are;

1. Improper soil pH

If you’re growing plants in containers and feeding regularly with premium plant fertilizers, soil pH probably isn’t the cause of your plant leaves turn yellow. But if your leaf problem centers on landscape plants, soil pH level may be the key. Carefully understanding the pH level of your garden soil is key to preventing yellow leaves in plants. If the pH is not properly balanced, the soil locks nutrients in, making them unavailable for uptake by the plant’s root system. Regular fertilization does nothing to improve nutrient deficiencies in an unbalanced soil pH level.

Soil pH level influences whether plants access nutrients. Nutrient availability changes as soil pH levels move up or down the pH scale. Most plants do best with soil pH in the neutral to slightly acidic range near 6.0 to 7.0. Acid-loving plants such as rhododendrons and blueberries prefer soil near 4.5 to 6.0 pH level.

When soil pH level strays lower or higher than a plant’s optimal range, some nutrients become less available to it. Leaves turn yellow until pH level issues are fixed. A simple soil test identifies soil pH and provides other important information. Most testing labs also give recommendations for soil amendments to restore pH level balance. Once that happens, nutrients become available again and green colour leaves are back on track.

2. Moisture Stress

The common reason that plants’ leaves turn yellow is because of moisture stress, which can be from either overwatering or under-watering. If you have yellow plant leaves, check the soil in the pot to see if the soil is dry. Overwatering or under-watering are the most common culprits when leaves turn yellow.

Overwatering your Houseplants

Watering issues are the most common cause of yellowing leaves. Overwatering on indoor plants is one of the most popular reasons for leaves to turn yellow. When your indoor plants are overwatered, the performance and vigour decrease. Oxygen is being pushed out of the soil, and the plant roots are simply “under aired” and suffocating. With little air, the plant roots will begin to drown and rot. Overwatering plants also leads to various fungal diseases. Check the moisture level in the soil and dig down a few inches near the stem of the plant. Take a small handful of soil and then squeeze it. If it’s moist or cool to the touch, it doesn’t need more water than the plants at the moment.

Remedy – First, reduce the watering frequency. Water deeper and less often. Also, add air to the soil by poking holes deep around the root zone by using a screwdriver. If your plants are in a container or pot, drill a hole in the bottom of the pot and make sure the soil drains well.

Under-watering – This one is a slightly more widespread reason for yellow plant leaves because we’re human and sometimes we just forget to take care of our plants. But if this happens too often, you’ll get yellow leaves in plants that are dry and crunchy to the touch. Get the watering can and start watering the plants.

3. Sunlight

Another common reason that leaves turn yellow is that not enough light is reaching the plant. The plant leaves turning yellow when the plant receives too little sunlight. Then, this occurs because the rate of photosynthesis is limited in low light, but as the light is increased, photosynthesis increases as well. Plants that receive too little light will start to yellow on the lower plant leaves before those leaves drop. If this is your problem, there is prevention that you can look for. When a plant becomes thick, it sometimes blocks light from reaching inner and lower leaves on plants. These plant leaves cannot photosynthesize and chlorophyll production comes to a halt. Since the plant leaves are non-productive, the plant no longer needs them.

Partial shade plants and Cole crops like lettuce are susceptible to burning and turning yellow in the hot summer months. It’s best to plant these vegetables (or flowers) in early spring or fall, or partly shaded areas. Though, if they’re already growing strong, try to give them a break from direct sunlight in the heat of the day.

Treatment – Simply remove non-productive yellowing plant leaves. The plant will be fine without them. On plants that don’t perform well in direct sunlight, screen them in the mid-afternoon to prevent leaves from burning. If the plants growing in pots move them to a more shady part of the yard when outside temperatures begin to soar.

4. Temperature

The temperature contributes to the colour of the plant leaves as well, when it is either too hot or too cold. In terms of the cold temperatures, cold drafts on most tropical plants will contribute to the yellowing of the leaves in plants. If it is not periodic temperature change like a draft, the plant leaves will most likely be brown if they are exposed to prolonged cold temperatures, especially when they are positioned near an air conditioner.

5. Root damaged or compacted roots

Root damage happens in several ways, from wayward shovels to root rot and another disease. Once damaged, plant roots may struggle to deliver what your plant needs. When container growing plants outgrow their pots, compacted roots result. In these cases, roots can’t function properly and problems manifest as yellow colour leaves.

To check containers for damaged plant roots, gently slide your plant out of its pot. Healthy roots are whitish-yellow. Dark, rotting roots smell foul. If roots are rotten, it’s time to consider a new plant. If compaction’s the problem, prune unhealthy plant roots, gently loosen roots and repot in a larger container with well-draining soil. Incorporate organic matter and organic mulch into planting sites. Also, garden gypsum can improve soil compaction, especially in heavy clay soils, and help keep leaves green.

6. Viral Infection

If your plant has a viral infection, it might show up as blotchy, spreading yellow patches on plant leaves. This can be accompanied by deformed leaves and stems, as well as discoloured flowers. Viral infections in indoor plants cannot be cured and can infect all susceptible plants nearby. While it can be painful if it’s a favourite, discard any plants that you suspect are infected. The solutions for this problem are washing and sterilize any pruning tools or pots before using other plants.

7. Plant nutrition

The yellowing of your plant leaves can also be a good indication of their nutrition. Common sources of nutrient issues are under-fertilizing or over-fertilizing, so it is very important to use fertilizer at the labelled rate. Some gardeners use too much fertilizer on plants to make them grow faster, but what it does is create a toxic environment which “burns” the leaves out causing the plant leaves to turn a yellow colour.

Nutrient Deficiency

Nutrient Deficiency.
Nutrient Deficiency

Nutrient deficiencies in plants occur due to insufficient amounts in the soil or because the nutrients are unavailable due to the high pH level in the soil. Or nutrients may not be absorbed due to injured plant roots or poor root growth. Plant leaves may also turn yellow colour if a plant is not receiving all of the nutrients it requires. Then, this can be caused by too much calcium in the water if you’re using hard water or by a nitrogen deficiency.

If this is the problem, the plant’s top leaves can be the first to go yellow. In other cases, you may notice an unusual pattern to the yellowing. For instance, the veins may remain dark while the tissue between them turns yellow colour. The nutrients a plant requires changes based on the species and some are pickier than others. Then, it is important to try and diagnose the problem properly or you might kill a plant that can otherwise be brought back to health.

Nutrient deficiencies in plants can be treated in one of several ways;

Get a soil test to determine soil pH level and nutrient levels. Iron becomes more insoluble and less available to plants as soil pH level goes above 6.5 to 6.7 [7.0-neutral; below 7.0-acidic; above 7.0-alkaline]. Some plants such as blueberries, rhododendrons, azaleas, and pin oaks have a high need for iron, hence their acidic soil requirement.

High amounts of other elements like calcium, zinc, manganese, phosphorus, or copper in the soil can make iron unavailable to the plant. Also, a shortage of potassium in the plant will reduce iron availability. Insufficient iron in the soil may be the cause. Based on a soil test, the pH level can be lowered by adding sulfur or the appropriate nutrients can be applied.

Identifying which leaves turn yellow first and how the yellowing starts provides signs of common deficiencies such as;

  • Nitrogen deficiency shows up as a general yellowing colour. Older, inner plant leaves turn yellow first. As it progresses, yellowing moves outward, eventually reaching young plant leaves, too.
  • Potassium deficiency shows itself when leaf edges turn a bright yellow colour, but the inner leaf stays green. Older plant leaves show symptoms first, and leaf edges soon turn brown.
  • Magnesium deficiency starts as yellow patches between leaf veins on older leaves in plants. Veins stay green as yellow colour moves from the leaf centre out. Leaf edges turn yellow last.
  • Iron deficiency in plants also shows as yellowing between leaf veins, but it hits young leaves on plant tops and branch tips first.
  • Sulfur deficiency starts with the newest plant leaves, turning them yellow throughout.

Relationships between soil nutrients and plants are complex. E.g., low potassium can make iron less available. Yet excess potassium ties up calcium, nitrogen, and magnesium causing deficiencies of those nutrients. That makes proper fertilization with trusted, premium plant foods crucial to keeping plant free from yellow leaves.

Yellow Leaves on the Lower Part of Your Houseplants

There are three possible reasons and treatments for yellow leaves on the lower part of plants. First, if plant roots are pushing through the bottom of the container it means the plant has run out of the room and needs to be repotted into a bigger container with some extra potting mix. Second, the soil can be low in nitrogen, an important nutrient that plants need to grow properly. Lower leaves are the first to starting yellowing when a plant doesn’t have enough of this element. Over time, your plants can use up all the nitrogen that the potting mix may come with, so repotting with fresh soil can help with this problem, too. Or, you can supplement with a fertilizer that is high in nitrogen levels. Third, moving your plant to a brighter spot to see if more light helps green up its leaves.

Why Plant Leaves Turn Yellow in Containers

Because of the closed environment in container plants, the conditions should be carefully controlled. There is a limited amount of space, area to store moisture, a nutrient in the medium, and lighting, and temperature should be considered for each species of a potted plant. Our plants have leaves turning yellow due to nutrient deficiency or excess salt in the soil from too much fertilizer. It can be necessary to change the soil or leach it with large amounts of water to correct the balance. Of course, changing the soil can trigger a condition called transplant shock, which also causes yellowing leaves. Indoor plants are tropical and something as simple as changing the plant’s location can produce yellowing leaves on plants. This is due to stress but can also indicate low light or exposure to a draft. The pH level may also be too high, causing a condition called chlorosis. Then, it is a good idea to use a pH meter in potted plants to ensure the correct growing conditions. Overhead watering is yet another cause for yellow “water spots” on plants like gloxinia, African violet, and several other plant species with slightly furred foliage.

Pests and Diseases for Yellowing Plant Diseases

The yellowing of your plant leaves is also caused by pests and diseases. Some important pests affected in indoor plants are Mites, Aphids, Mealybugs, Thrips, Scale, and Whiteflies. If the yellow spots on your plant leaves appear along with tiny critters (be sure to check the undersides of the leaves), then you have an insect problem. First, identify the pest on plants and then treat for that particular insect. Typical bug infestations on plants are caused by mites, aphids, mealybugs, thrips, scale, or whiteflies. Repeatedly washing the plants or applying an insecticidal or horticultural soap is one treatment that is effective as well as environmentally safe.

To promote growth and deter mould and pests like fungus gnats, it is sometimes necessary to trim and remove dead leaves from plants. Then, this helps the plant send energy to the healthiest leaves, as yellow leaves will not turn green again.

You should not miss this: Growing Organic Spinach At Home.

How Can You Prevent Yellow Leaves?

Keep your indoor plants strong and healthy. Here are a few tips to prevent yellow leaves;

  • Use a moisture meter, so that you only water your indoor plant when it needs it.
  • Check your indoor plants over at least once a week, preferably twice, so that any problems can be identified and dealt with quickly.
  • Water your houseplants with room temperature water. Either leave it out overnight or add a bit of hot water in plants.
  • Make sure your indoor plants are getting the right amount of light and humidity. Add grow lights and humidifiers if necessary, but closing doors and cleaning windows go a surprisingly long way.
  • Keep your plants dust-free by regularly wiping them with a cloth dipped in a neem oil solution and warm water solution.

In case if you are interested in this: Organic Farming In India.


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