What indoor gardener hasn’t asked this question? As wonderful as they are, both for your health and your décor, it can sometimes seem that houseplants just love to die—especially if you’re relatively new to indoor gardening. Perhaps worse yet, in many cases, gardeners are mystified by exactly why their beloved plant died.
The good news is that plants really don't just die without a reason. In fact, houseplants are fairly predictable, depending on their species, and the vast majority of houseplant casualties are all caused by the same few factors. Here are the top reasons houseplants die.
Too Much Water
Too much water may seem impossible but in reality, it's not only possible but a very common mistake people make. There are very few plants that can handle daily watering in a typical potting situation, even many of the tropical plants we love indoors. The old advice about waiting until the top inch of soil is dry is a pretty good rule of thumb. You can also look for signs of thirst in your plant, including drooping or wilting leaves. In general, you shouldn’t water your plants until they need it.
This is the first cousin to overwatering. Watering and drainage are so closely related, it’s hard to draw a distinction between them, but there’s no question that bad drainage kills a lot of plants. Poorly drained pots, which can include root-bound plants or simply old potting soil, can easily retain water in the bottom of the pot, even if it’s drier higher up. The result is roots that sit in water, creating the perfect conditions for root rot. Similarly, many people water their plants until the water runs out into the tray, but then they don’t empty the tray so the plant is literally sitting in a pond. This is also an invitation for root rot. As a rule, the better your drainage is, the more frequently you can water and the more latitude you have to make mistakes with watering.
It’s all too common that a plant owner will have a plant for a year or two, during which time the plant thrives and looks great, only to be startled and confused when the plant starts to fail for no reason. In many cases, this is caused by a root-bound plant that is no longer receiving adequate nutrition from the soil (because there’s hardly any left). Not all plants need to be repotted every year, but you should frequently check for root-bound plants.
Using Old Potting Soil
This is also closely related to not repotting. Most potting soils are based on peat, which breaks down over time and becomes more acidic. As peat breaks down, it becomes harder for water and oxygen to fully infuse the root zone, so the plant will starve slowly even if nothing else changes (e.g., your watering schedule). The best solution here is to repot when the plant needs it. If your plant is too old, take cuttings.
Not Enough Water
This is mostly caused by neglect, so it’s a safe bet that people who let their plants die from lack of water really just don’t care.
Notice the conspicuous absence of light and fertilizer issues on this list. The truth is that, if you’re getting the watering and drainage portion right, many plants can be very adaptable. A plant with a healthy root zone can often survive fluctuations in temperature, imperfect lighting conditions, and even less-than-ideal light levels. In this way, plants are a bit like houses: they need a strong foundation to thrive. That said, if you can provide the ideal amount of light and a judicious hand with the fertilizer, your plants will thrive.
Lastly, if you do find you’re killing a lot of plants, maybe it’s time to switch to buying tougher houseplants and gradually working up to the more challenging plants.
How to Water Indoor Plants. Missouri Botanical Garden
Repotting Houseplants. Pennsylvania State Extension