Article and Photos by Evin Morrison, Extension Master Gardener
One day you look up, only to notice that one of your plants is looking a little droopy, maybe it’s even slightly changed color. So, what do you do? You swear it was fine last time you watered it and that can’t have been that long ago, can it? It’s time for a little detective work to figure out what’s ailing your sad plant and what can be done to get it back to its former glory.
First Things First, Grab Some Good Lighting
Move your plant to the brightest window or under a bright lamp so that you can give it a close look. Often, with quickly declining plants, a pest may be causing the damage. These pests are usually very small and/or hidden in the crevices of the petioles and stems or on the underside of the leaves, hence the need for good lighting. Break out the Sherlock Holmes magnifying glass, get close, and do a full inspection. Unfortunately, usually if we notice the damage, the infestation is likely advanced, and action will need to be taken. Of course, treatment often depends on the type of pest, so identify exactly what the problem is first.
Repeat the treatment, as needed. Photo © Evin Morrison
But how did your plant get pests in the first place? Remember that most infestations happen when a plant is already stressed or in decline. Plants that are struggling from ill-suited watering, nutrients, or air quality will produce pheromones, which in turn, attract pests. Before you know it, that plant takes a turn for the worse because the environmental stresses combined with pests are just too much for it to handle.
Beware of Common Pests:
Spider mites will make themselves known by spinning very delicate webs on the undersides of leaves and in the joins of stems. Their tell on your plant is teeny tiny spotting and yellowing on the leaves.
Thrips are even harder to spot but can usually be found on the underside of leaves. They are very small, long-bodied pests that suck the life out of leaves. These are usually a little harder to get rid of because unlike other pests they are quick to move and hard to spot again, so spot treating them is nearly impossible.
Mealy bugs are quite often very easy to spot as they present themselves as fuzzy, white specs that attach to your plants. However, they breed quickly, and the nymphs are too small to see, so if you have an infested plant you will want to check it regularly to make sure they aren’t maturing on your plant and starting the process all over again.
For ways to treat these pests and more visit our previous article: Managing Houseplant Pests.
Be aware that you can introduce pests into your home if you aren’t careful. Be sure to thoroughly inspect plants at the store before you bring them home, otherwise you are bound to pick up a few unwanted hitchhikers here and there. If you happen to bring some home and nestle the plant in with others, it can become a pest highway and infest a number of otherwise healthy plants in close proximity. To avoid accidentally introducing a pest into your plant collection, consider keeping new plants quarantined for a week or two to allow observation of activity from previously hidden bugs. Make sure your quarantine area is away from any drafts or air vents as pests can use a gust of air to travel from plant to plant.
No Pests, Yet Still a Problem?
Photo © Evin Morrison
Take a deep breath. You survived the initial inspection and have come away pest-free. So why is your plant still in decline? It’s time to gather a little background data and hopefully you’ll find an answer. When did you purchase this plant? How long has it lived in this pot? Do you still have the plant tag that came with the plant and are you sticking to the care instructions?
If your plant has been in the same pot for longer than a year, it’s probably time to repot it. We often forget that plants growing in the wild are in soil that is constantly replenished with nutrients. It’s an ecosystem of living things that allows the plant to consistently get the food it needs to grow. In a pot, however, a thriving plant can quickly use up all the nutrients in the soil and then be left completely depleted.
To avoid nutrient depletion, feed your plants on a regular schedule. Find a plant food that best fits your plant care style, either a liquid that gets diluted into water every few weeks or a granular time release fertilizer for houseplant soil added in accordance with package instructions. After a while, even adding in synthetic fertilizers can cause buildup of too many of some compounds and not enough of the others. Unless you are top dressing with compost or worm castings, there’s no real organic content entering the container and the soil can get out of balance over time. By repotting in fresh soil and sticking to your chosen fertilizing routine, you can avoid depleting your plants of all the nutrients they need to grow. Remember, “more is more” is not the case for fertilizers and houseplants. Too much fertilizer in one pot can and will cause fertilizer burn on your leaves.
Photo © Evin Morrison
But the yellowing leaves that often catch our attention are more often the result of not enough fertilizer rather than too little. Chlorosis is a common problem in houseplants that cannot access enough nutrients in the soil. Chlorotic plants’ leaves appear yellow with green veining. Outdoor gardens with high pH soil can also exhibit plants with chlorosis. The nutrients the plant needs to have sufficient chlorophyll get bound up in the alkaline soil and the plant can’t use them. If caught early enough, the plant can be fed and the leaves return to a healthy green. Adding iron supplements to the soil usually helps the plants bounce back from chlorosis. However, if the yellowed leaves are too unsightly, you can prune away the worst offenders and with the fertilizer bump your plant should be putting off new healthy growth in no time.
Still Haven’t Found Your Answer?
If you are sure there are no pests, and you know the soil is still nutrient-dense then it’s time for an exhumation.
Photo © Evin Morrison
We save this step for last because it’s best to not unpot a plant that hasn’t outgrown its home if you can help it. Like most people, plants don’t like change. Ficus trees are known to drop leaves when moved to new locations and it’s all due to the stress caused by abruptly changing the environment. So as a last resort to your investigation, you need to pull the plant out of the pot and see what’s been happening underneath the soil.
Because yellowing leaves and drooping stems can be signs of both under and overwatering, looking at the root system can help you decipher which one you might be guilty of.
Under-watered roots will be dry and papery. They will snap easily when bent and aren’t helping to provide nutrient uptake or anchoring for the plant. These roots are dead and should be removed. If you have an under-watered plant with a lot of dead roots and then start watering it regularly, you’ll end up with a severe case of root rot, as the dead roots will quickly begin to decompose. In nature, when a plant or its parts die there are thousands of organisms that break down the organic matter and contribute it back into the healthy soil. In a planter, that organic material has nowhere to go, but to rot in place. This root rot can spread to the healthy roots, soon leaving you with a pot of floppy and stringy roots no longer able to support the plant.
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This same problem can occur with overwatered roots. When the soil is constantly wet, the roots are never able to obtain the oxygen they need. Once again, they end up rotting and can quickly lead to a dead and smelly plant. If you find that when you pull the plant out and the soil around the root ball is very wet, especially if it’s been a few days since you watered, there’s a good chance that the pot doesn’t have adequate drainage. To improve this, you should first make sure that the drainage holes aren’t clogged and trapping water. Then next time you pot the plant add a gritty substrate like perlite to the soil to improve drainage. If you are a serial over-waterer try adding something like horticultural charcoal, which will add grit and natural antimicrobial properties that help keep root rot at bay. Of course, adjusting watering habits is the best way to avoid either of these problems.
Wash your plant’s roots in cool water so you can see what you are dealing with. Healthy roots are usually a pale green or white color and should be firm. Rotted roots will be brown and squishy. These rotted roots will usually come away in your hands when pulled on and can also be a bit stinky. Take the time to trim off all the rotted material with clean scissors before repotting.
Luckily, with a little grooming of the roots and the yellowed leaves, and a change in watering habits, most plants can recover and put out new growth once they are repotted.
Photo © Evin Morrison
A different issue you may discover after not repotting your plant for a while is that the roots have outgrown the container. When there are more roots than soil, the plant can’t capture water as efficiently because the soil isn’t holding onto any moisture between watering. Instead, the water drains through the root system and out of the container. You will notice that the plant seems to dry out faster and you’ll find yourself watering it a lot more often to no avail.
In cases where roots have wrapped around the pot and strangled the roots underneath, the plant is described as being “pot bound” or “root bound.” This condition can lead to big problems for your plant over time. Roots need to be able to breath freely, but when condensed in a tangle like the ones you see in pot-bound plants, the outer roots may be fine, but the inner roots are unable to dry out properly and “breathe”. Simply moving the plant to a larger container with fresh soil isn’t going to be enough to create a healthy root system again. You will need to break the roots up and create space for the inner-most root growth. That way, when you repot it, all roots will be able to absorb water and air from the soil rather than be trapped inside a mat of organic matter.
Ailing Plant Problem Solved?
Our houseplants, like all things in nature, are complex. We are drawn to acquire plants for our coffee tables and bookshelves that are meant to live in specific regions of the world, so there are bound to be a few problems here and there. Figuring out the root to a houseplant problem can be a lot like detective work, with a little guess and check thrown in for good measure. There’s nothing elementary about it, but the more house plants you acquire, the clearer the signs become, and soon you’ll be targeting signals of a declining plant before it’s too late.
Still can’t find the problem? Send us a few pictures and a description of the problem. Our Help Desk Team can help point you in the right direction: https://mgnv.org/programs/help-desk/.