Have you ever looked at your once thriving Spider plant and recoiled in horror that its leaves have turned black?
Don’t worry; these gardening woes happen to the best of us! In this article, I use my first-hand experience to help you diagnose the reason your spider plant leaves are turning black and for my tips and tricks to help save your plant!
Let’s get straight to the point…
Spider plant leaves turn black when exposed to cold temperatures and frost. They are also frost-sensitive and often turn black when in contact with a cold window indoors. Root rot and fungal pathogens caused by overwatering can also turn spider plant leaves black.
Keep reading to learn what has caused your spider plant leaves to turn black…
Cold Temperature Causes Black Leaves
So, I wrote about each problem in the order of prevalence, and backend leaves due to cold weather is something I encounter a lot, even indoors…
Our Spider plants (Chlorophytum comosum) are tropical plants that are native to Southern Africa where they grow in relatively warm conditions with bright indirect light and relatively high humidity.
Spider plants grow very well in our homes as their optimal temperature for growth is around room temperature at between 65°F (18°C) and 75°F (23°C) during the day and warmer than 55°F (12°C) at night.
It is important to note they do not tolerate cold or frost being hardy to zone 10.
Spider plants are hardy and resilient plants and tolerate the occasional period of cold but if the temperature is significantly colder than 55°F (12°C) spider plants show signs of stress with their leaves turning brown or black.
What I’ve found is that Spider plant leaves turn black substantially if there is a significant drop in temperature, such as exposure to frost.
This once happenedd to me because the spider plant is next to a window. If the leaves are in contact with a cold window on a frosty Winters morning then the leaves that are touching the Window tend to turn black.
To prevent further damage, always locate your spider plant away from draughty, cold areas of the house and ensure that the leaves are not in contact with any windows.
All that I had to do was snip off the affected black leaves at the base of the plant, as the individual damaged leaves do not tend to recover due to the spider plant’s sensitivity to the cold.
I haven’t seen black leaves occur indoors other then when the leaves are in contact wit the window, but I do know that sometimes people in warmer climates move their spider plants outdoors in the Summer which can sometimes be a problem if the discrepancy between the hot day temperature and night time temperature is particularly significant even if the temperature does not go below freezing.
Root Rot Causes Leaves to Turn Black
Spider plant leaves also turn yellow and black when they are in damp or saturated soil for too long, which promotes the conditions for pathogens of fungal diseases such as root rot.
Whilst your spider plant prefers humid air, it does not tolerate its roots sitting in boggy soil.
Spider plants require the soil to be evenly moist yet well draining to stay healthy.
Ideally, the top inch of the soil should dry out between bouts of watering to maintain the optimal balance of moisture.
However, we should be aware that root rot or other fungal diseases can be caused by:
- Watering your spider plant too often.
- Slow-draining soils.
- Pots without drainage holes in the base or saucers, trays, or decorative outer pots that prevent water from escaping.
- Large pots that take a long time to dry out.
If your spider plant has root rot or a fungal disease and the leaves have turned black then it is very difficult to revive the plant (unless you can propagate any spiderettes that have formed) so, I’m afriad that prevention is better than cure.
(For more information, read my article, how to revive a dying spider plant).
How To Prevent Spider Plant Leaves from Turning Black
Avoid Over Watering Your Spider Plants
As mentioned before, the best practice for watering spider plants is to wait for the top inch of the soil to feel dry.
I have done lots of testing with my spider plants in regard to watering frequency and I personally find that watering once every 7-10 days is best, but it can vary according to climate.
Pro Tip: I account for the differences in climate by monitoring how long it takes for the top inch of the soil to dry out by testing with my finger to detect any moisture.
If the soil feels damp, then I delay watering. As soon as the soil feels somewhat dry, this is the perfect time for watering.
This balance of watering ensures the spider plant has all the moisture it requires for active growth, yet the soil is not too damp and risks root rot.
(To learn all the best practices for watering read my article, must-know tips for watering spider plants).
Slow Draining Soils
From my experience, my spider plants are not fussy about soil type but their potting soil should should be porous and well draining.
Conventional potting soil is ideal for growing spider plants as retains some moisture yet allows excess water to drain away from the roots.
I have experimented with amending the soil with grit, perlite, sand, or orchid potting mix. I found that my spider plants grew well in all soil amendments, but my spider plant thrived when I added around 20% orchid pine bark potting mix to the spider plants potting medium.
I concluded that this is because it most closely replicates the soil conditions of the spider plant’s native woodland environment.
Sometimes, compacted soil (or roots) can block the drainage in the base of the pot, preventing water from draining and increasing the risk of root rot. Spider plants grow thick, fleshy roots, which I’ve seen block draining holes! So my advice is always to check the bottom of the pot to see if you notice the soil draining slowly after watering.
Plant Spider Plants in Pots with Drainage Holes in the Base
Your spider plants must be in pots or containers with drainage holes to allow excess water to escape so the plant can stay healthy.
I saw one spider plant that had black leaves that was growing in a hanging basket. When I inspected it, I found that there was a plastic lining in the pot, which was impermeable, and the soil was consistently damp, hence the black leaves.
If the spider plants are in decorative pots without drainage holes, excess water pools around the roots and causes root rot.
Also, I use saucers and trays to prevent water from spilling in the home, but this can cause the bottom of the soil around the roots of your spider plant to be damp if they are not emptied regularly.
Larger Pots Take Longer to Dry Out
I have grown spider plants for a long time, and I’ve always found that they grow best in pots that are just a bit larger than the root ball.
I did some testing and found a pot this size promotes flowering and the development of spiderettes that can be used for propagation.
(Read my article, Spider Plant Not Growing and Not Producing Babies, for more information).
The problem with larger pots is that they contain more soil and, therefore, have a greater capacity for moisture.
This means that a larger pot can take significantly longer to dry out compared to smaller pots which increases the risk of root rot.
Therefore, I recommend always planting your spider plant in a pot that is proportional to the size of its root ball to ensure that the soil does not remain damp for too long to avoid your spider plant leaves turning black.
My Best Tip: If you are having trouble with spider plant leaves turning black, then I recommend planting your spider plant in clay pots, as clay is porous, which allows the soil to dry out more evenly, whereas plastic pots are impermeable which can retain too much water for our spider plants to tolerate.
Read my article, How to Grow and Care for Indoor Spider Plants.
If you are having any more problems with your spider plants or have any insights you’d like to share, please leave a comment below!!
Key Takeaways:
- Spider plant leaves turn black when they are exposed to cold temperatures. Spider plants are cold hardy to USDA zone 10 and turn black if they are exposed to frost. Often, spider plant leaves turn black when they are in contact with a cold window during Winter.
- Snip off the black, cold, or frost-damaged spider plant leaves at the base of the plant.
- Spider plants can turn black because of root rot and other fungal pathogens. Root rot is caused by overwatering, slow-draining soils and pots without drainage holes in the base.
- Always plant spider plants in pots with drainage holes in the base and only water when the top inch of the soil has dried. Empty saucers and trays of excess water regularly to avoid root rot.