For the love of God, and all things good, PLEASE hole your containers!
There are few things as contradictory as a self-professed plant lover growing his/her beloved plants in a container with no holes. What should seem to be common sense, that plants will need to vent, just as we humans do - especially if they keep getting watered and fed (!) - is apparently, esoteric wisdom to many.
Here are some photos, mainly from gift shops, where neither the seller nor the gifter seem to care about how these plants will survive once they are gifted.
Trendy tropicals in un-holed containers - ready for gifting and root rot!
Another frequent offender seems to be the interior planner/architect. Inspired by the beauty of foliage bursting directly out of designer planters, and less by plant drainage, we often see this:
Beautiful foliage in beautiful containers - but where's the water going to go?
All plants need good drainage. When grown naturally in open soil, excess water flows radially and vertically/downward from plant roots. When transplanted and "contained" in pretty pots of our choosing, all radial drainage options cease immediately (except if you are growing in unglazed terracotta or fabric containers). Plants then need to keep up their show with vertical/downward drainage only. If this too is blocked - as in the examples shown above - plants suffer a fate close to constipation, for want of a more appropriate word! Don't believe me? Excavate the soil in plants growing in un-holed containers and give it a good sniff!!!
More seriously, root rot is real. As are bacteria and excess salts that will accumulate in the depths of un-holed containers. All plants are susceptible, but desertified species (think cactii and succulents) more so than tropical plants. While the former will be incapable of absorbing extra water and unhesitatingly lie down and die after too deep or long a drink, the latter may put up a good fight for some time before raising serious objections.
So, feed your plants food and water appropriate to their type, and make way for the excess to flow out as naturally as possible. Ensure your indoor potted plants are holed, and that drip trays are frequently emptied. Here are a few exceptions to this golden rule:
Hardy, water-guzzling tropicals like Pothos/Money Plants (Epipremnum Aureum) - if, and only if, you ensure complete dryness of soil between watering events.
More resilient cacti like Snake Plants (Dracaena Sanseiveria) - if, and only if, you are disciplined about water dosage and ensure you never, ever, ever over-water.
In both cases, I recommend using glass containers, especially if you are a new grower. This will offer a visual check of how wet the soil is before you go ahead and give your plants another dunking. Once you get the hang of it, and succeed in keeping your un-holed container plants alive and not smelling foul for a decent length of time, you could explore materials other than glass - but do stick to hardy and resilient plants only.
Good luck with the growing!
(Images in this post are sourced from the Internet. Please contact re objections/credits, thank you!)