Can I use a decorative pot that has no drainage hole?

Yes—as an outer pot, not usually as the pot you plant directly into. Place the plant in a separate inner pot with drainage holes, then set that pot inside the decorative one. This arrangement is often called a cachepot setup. For houseplants, Penn State Extension recommends a draining inner pot and says decorative cachepots generally aren’t suitable for planting directly. [S1]

Before adding the inner pot, check that its base can sit above the bottom of the decorative pot rather than sealing against it. Leave space beneath the drainage hole so water can flow freely; a saucer can be used if needed. [S1]

Treat that as a fit problem to solve before watering. Choose an inner pot that leaves clearance beneath its drainage opening, or use a saucer inside the decorative pot if it provides a stable way to keep the opening clear. The goal is for water leaving the inner pot to have somewhere to go—not to have the opening blocked by the outer pot’s base. Penn State Extension advises leaving space below the inner pot’s drainage hole and mentions a saucer as an option. [S1]

For example, if the inner pot’s base covers its drainage opening when nested, lift it out and try a different fit or a saucer. Check that the arrangement is stable and that collected water can be removed.

After watering, take out the inner pot if practical and pour away excess water from the cachepot; alternatively, remove the collected water without disturbing the plant. Penn State Extension advises removing excess water from a cachepot after watering. [S1]

You can make this easier by choosing an inner pot that is simple to lift and an outer pot you can empty without spilling. There isn’t a universal watering schedule established by this guidance, so it can’t tell you how often your particular plant needs water. It explains how to arrange and maintain the pots, not when to water.

No—don’t treat gravel as a replacement for a drainage hole. Penn State Extension says a layer of pebbles under houseplant potting mix does not promote drainage and can retain moisture in the pot. [S2] The recommended arrangement described for houseplants is a plant in a draining inner pot, nested inside the decorative pot, with room beneath the drainage opening and excess water emptied afterward. [S1]

For example, the setup could be: plant in draining inner pot → optional saucer or clear space → decorative outer pot → empty collected water after watering. This guidance is about houseplants; it does not establish the right arrangement for every plant species or outdoor container. Check guidance specific to your plant rather than assuming this setup determines when it needs water.