If you have the option to choose, always get a pot with good drainage or drill one yourself. However, if you are growing succulents indoors and want to use pots without drainage holes and not worry about water coming out the bottom of the pot, there are a few tricks that can help you minimize the risk of killing your plants.
The Root of the Problem
For succulents to stay healthy, their roots need air. Overwatering causes a number of diseases, and without taking steps to prevent wet roots, your plants may succumb.
Scab is a disease caused by excess water. Symptoms include corky brown scabs appearing on the stems of the succulent. Some cacti are especially susceptible to scab. Decrease watering and increase light to fight scab.
Stem and root rot can kill overwatered succulents. Various soil fungi multiply in the presence of excess water. The plant wilt and a brown or black ring appear at the stem's base, above the soil. If only the roots show disease, cut away rotted roots with a sharp knife and repot the plant in sterile soil. Wipe the blade between cuts with a cloth soaked in rubbing alcohol to help prevent spreading the fungi.
Working With Containers That Do Not Drain
A few tricks help minimize the risk of diseases from wet soil. The main trick is to water the plant normally, but after a few minutes, tip the planter sideways and drain out excess water.
Double potting helps overcome the problem of no drainage holes in a planter. Grow the succulent in a pot liner or smaller container that can sit inside the larger, non-draining container. Make at least four holes in the liner or small container if it does not have them. Layer the bottom of the larger, outer planter with gravel.
After watering the plant, wait a few minutes for excess water to drip out of the smaller container. Lift the plant in the liner from the larger container and dump the excess water. After draining, place the liner or small planter back inside the larger one.
If the container does not have drain holes, you will need to be more careful with watering. Water the container only enough to wet the top inch (2.5 cm) of soil. Allow the soil to dry completely before watering again. It should only need watering once every two weeks.
Potting Soil Choices
Succulents require soil that is loose and drains well. A cactus or succulent soil from the garden center work, or you can mix your own. When preparing the soil for a container, use a mixture that contains equal portions of sand and garden soil. If your budget allows, a better soil mixture is equal parts loam, sand, and perlite.
Test the soil's quality by moistening a handful of the mixture and trying to squeeze it into a ball. If it is the proper consistency for succulents, the soil will not become compacted but will fall apart.
Cacti only require fertilizer once or twice each year, during spring and summer, while other succulents should be fertilized three to four times during the summer. Choose a houseplant fertilizer such as 3-7-7 that has more phosphorus than nitrogen.
Dilute the mixture to one-half the standard concentration recommended on the product label, so mix 5 to 10 drops in 1 quart of water instead of 10 to 20 drops. Check the instructions as rates vary by brand. Soak the top 0.5 inches (1.2 cm) of soil around the plants completely. Use the fertilizer solution in place of regular watering.
The Right Light
Succulents need the right amount of light to keep them healthy. Outdoors, place them in full sun or part shade. Indoors, placing the planter near a sunny window should provide enough light, but a cool white fluorescent tube is a good substitute if direct sunlight is lacking. Place the tube 6 to 12 inches (15 to 30 cm) above the plant for 14 to 16 hours each day. Use a timer to help automate the process.
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