Ceramic Pots make wonderful Water Garden bringing the serenity of a pond to you with out the expense. 95% of ceramic pots made have holes in them for drainage, worry not because these holes can be sealed relatively easily, though not all ceramic pots are created equal. For best results make sure to use a Chinese or Vietnamese High fire Ceramic pots.
What you need
1/4 Cup Ceramic Cement
1 quart zip-lock bag
Turn the pot upside down and cross 2 pieces of duct tape over the hole (Make sure bottom of pot is dry before applying duct tape.)
Dampen hole and small area inside the bottom of the pot.
Mix hydraulic cement in small qt bag to a tooth paste consistency or (slightly) runnier. Best to do small batches since it sets up so fast
Cut corner of bag and squeeze out like pastry bag, patting out air bubbles as you pack the hole and create a mushroom shape plug. ( Dome should be ¼ – ½ inches wider than hole) Clean up any
After 15 minutes check on the curing process dampen and smooth mushroom cap to prevent cracking and create a finished look.
After 3 hours Fill pot with water and test for leaks. leave filled for at least 24 hours and check water level. (if your pot is leaking then you might need Seal the inside of the Pot
For Best Results
Do not seal hole in direct sunlight (sunlight can lead to cracking and the concrete setting up to quickly)
The quicker you use the cement the better it works.
Clean the bottom of the pot and making sure it is dry before Applying Duct tape makes for a better seal.
if the bottom of the ceramic pot is concave then applying paper towel or other fill material between the duct tape and ground when you flip it over can give more pressure to the duct tape creating a better plug.
If you have cracking then do 2nd coat following same steps with new mixture.