Spider plant leaves turn black when the are exposed to cold temperatures and frost. Spider plant leaves are 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 Cause Black Leaves
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 the home as their optimal temperature for growth is around room temperature at between 65°F (18°C) 75°F (23°C) during the day and warmer then 55°F (12°C) at night.
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 then 55°F (12°C) spider plants go show signs of stress with their leaves turning brown or black.
Spider plant leaves turn black substantially if there is a significant drop in temperature such as exposure to frost.
This happens usually 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.
Always locate your spider plant away from any draughty cold areas of the house and ensure that the leaves are not in contact with any windows to prevent further damage.
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 plants sensitivity to the cold.
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 fungal disease pathogens such as root rot.
Whilst the 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.
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 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 form) so prevention is better then cure.
(For more information read my article, how to revive a dying spider plant).
How To Prevent Spider Plant Leaves Turning Black
Avoid Over Watering Your Spider Plants
As mentioned before, the best practices for watering spider plants is to wait for the top inch of the soil to feel dry.
Typically this means watering once every 7-10 days but it can vary according to climate.
Monitor how long it takes for the top inch of the soil to dry out by testing with your finger to detect any moisture.
If the soil feels damp then delay watering. As soon as the soil feels somewhat dry, this is the perfect time fore watering.
This balance of watering ensures the spider plant has all the moisture it requires fro active growth yet the soil is not too damp and risk root rot.
(To learn all the best practices for watering reading my article, must know tips for watering spider plants).
Slow Draining Soils
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 allow excess water to drain away from the roots.
Sometimes compacted soil (or roots) can block the drainage in the base of the pot which prevents water from draining and increase the risk of root rot, so check the bottom of the pot if you notice the soil draining slowly after watering.
Plant Spider plants in Pots with Drainage Holes in the Base
It is essential that your spider plants are in pots or containers with drainage holes to allow excess water to escape for the plant to stay healthy.
If the spider plants are in decorative pots without drainage holes, excess water pools around the roots and causes root rot.
Also the use of saucers and trays that prevent water spilling in the home can cause the bottom of the soil to be damp around the roots of your spider plant if they are not emptied regularly.
Larger Pots Take Longer to Dry Out
Spider plants grow best in pots that are just a bit larger then the root ball.
This 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 infomation).
Larger pots 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.
Plant 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.
- 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 over watering, 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.