If you are lucky enough to live in USDA Plant Hardiness Zones 9 through 11 then you can utilize the philodendron as a landscape plant. For the rest of us though, this plant grows wonderfully indoors. While this plant is easy to grow, it does have a few disease problems, which most are bacterial but some are due to over or under fertilization. Below are a list of these problems, what causes them, and what to do about it.
Bacterial Leaf Spot
The signs of bacterial leaf spot start on the margin of the leaves. Clear spots will appear along the edge of the leaf. As the disease progresses, this spot will turn reddish-brown with yellow edges. Larger spots will appear tan in color and be irregular in shape.
To keep this bacterial issue at bay starts off with checking the plant material before purchasing. If you see any of these symptoms, pass on the plant. Once you get it home, make sure to not water it from above. The best approach is to water from the bottom only.
Bacterial Blight Philodendron Selloum
If you find very small, dark green spots appearing on the leaves of your philodendron then chances are you have bacterial blight philodendron selloum. This plant disease starts off as the small spot but as it grows it moves onto the petiole of the leaf. Eventually, the leaf will collapse as a soggy mess, which smells terrible.
One of the ways you can invite this plant disease is through overhead watering. This type of watering causes moisture to pool on the leaves and petioles. Once that happens, conditions are right for this plant disease. To prevent it, only water the soil or water from the bottom. If the plant does not have a lot of leaves showing these symptoms, simply remove the affected leaves. If the plant has been taken over by this bacterial issue, throw the plant away. Do not compost any of the leaves or plants. This will prevent the bacteria from spreading further.
If you notice that the tips of the leaves are curling under and the margins are turning brown then you have tip curl. You many also notice that the roots along the stems and in the pot are dying. These plant problems are not caused by a bacterium but instead it is an issue with over fertilization. While it is important to feed your plants, too much of a good thing can be harmful.
Your inkling to deal with this issue may be to throw the plant away but do not. There are simple techniques by which one can “leach out” the excess fertilizer. The first thing you will need to do is to discover what type of fertilizer you are using. If you feed your plant every time you water during the growing season then stop the fertilization program. Continue watering as needed but only use pure water.
On the other hand, if you used a slow release fertilizer you can either leach the fertilizer out through the application of water or transplant the philodendron. When choosing the latter, make sure to remove as much of the “old” soil as possible and replant the philodendron in new, sterilized potting soil.
This is another type of fertilizer issue and that is there is not enough of a particular nutrient. In this case, it is magnesium. I know at this stage you are wondering why a plant needs magnesium. Well, magnesium is used in the process of photosynthesis. If the plant lacks sufficient levels of magnesium, it will have yellow colored “V-shapes” throughout the leaves. The treatment for this is easy and starts off with something that can be found in your bathroom. What is it? Well, it is good old fashion Epson salt. This first aid kit staple is actually magnesium sulfate, which is a wonderful fertilizer. To utilize this technique, mix 1 teaspoon of Epson salt to a gallon of water. When you go to water your plant, use this solution instead of plain water. In no time, your philodendron will be back to normal.
Even if you live in USDA Plant Hardiness Zones 9 through 11, there will be those few times that your area has a cold snap but there is also another way that your philodendron can suffer from cold injury and that is through bad placement. When planting outdoors, you need to make sure that it is in a location that remains above 50 degrees Fahrenheit. While that is easy to do if you live in the listed plant hardiness zones but……there is one area of your landscaping that you should avoid and that around the air conditioner. The air coming off this appliance can be below 50 degrees Fahrenheit. To avoid cold injury, plan your landscaping accordingly. On the other hand, if you are using your philodendron as part of your interscape then make sure you keep it out of cold drafts.
How do you know if your philodendron is suffering from cold injury? Take a look at the leaves. If you see really dark green or brown spots between the veins of the leaves then you have cold injury. The best solution to this problem is to never place your philodendron in an area that gets below 55 degrees Fahrenheit.
How to Water from the Bottom
You may have noticed that the best approach to keeping a bacterial problem under control when it comes to philodendrons is proper watering. While you can water very carefully and only get the soil wet but this really is an unrealistic approach. The best technique is to water from the bottom. While this technique sounds complicated, it really is not.
When it comes to watering from the bottom, you have two choices. One choice is designed for a plant that is already potted. The second technique can be done when you repot your plant.
Watering a philodendron that is already planted from the bottom only requires you to fill a saucer with water. Place the planted philodendron in the saucer and allow the soil to pull the water up. Please note that this technique only works if there is a drainage hole in the bottom of the pot.
The second approach utilizes a self-watering technique, which is very easy. Before you put your drainage material in the bottom of the pot, run some cotton cloth up through the drainage hole. Once that is done, add your drainage material and plant as usual. To water your plant, make sure that the cotton material is sitting in a container of water. The cotton will absorb the water and carry it to the roots but this will only work if the material is in contact with the root mass.