Vacation Watering

Almost every vacation-watering article starts by listing devices. That is the wrong end. Start with the volume of water your plants will need while you are away, because that number is knowable and it eliminates most of the options before you have read a single review.

Virginia Cooperative Extension publishes the frequency: tropical houseplants sometimes once or twice a week, succulents and cacti once or twice a month. We publish the volume of one thorough watering by pot diameter, derived from pot geometry on the methodology page. Multiply the two and you have the water budget for your trip. Then, and only then, look at what holds that much.

The trip-length budget

Now look at what the devices hold. A small watering globe holds roughly 118 ml - about half a cup. Put that against the 6-inch column and it covers a day and a half, which is why the two-week claim on the packaging has annoyed so many people. A 750 ml wine bottle on a terracotta spike covers the same pot for eight to fifteen days. A 2-liter soda bottle covers it for three to six weeks. A 5-gallon drip reservoir covers ten such plants for over a month.

Nothing here is a matter of opinion. The volumes are published or measurable, the cadence is published by an extension service, and the division is something you can do on your phone. The reason the category feels confusing is that the numbers are usually absent, not that the problem is hard.

The four things that fail while you are away

Evaporation from an open reservoir. A tray of water in a sunny window loses a surprising amount to the air, and the plants never see it. Site reservoirs out of direct sun and cover them if you can.

Air getting into a globe or bottle. These work by vacuum: water only leaves as air enters. Push a globe in at an angle and you widen the air path, and it can drain in hours instead of days. The one first-hand account we could find of somebody actually using globes reported exactly that, and a waterlogged spider plant to go with it.

A pump that stops. Drip kits are the only option here that genuinely covers a month, and they are also the only option with something to break. Test one for a full week while you are still at home. An untested pump is worse than no pump, because you have stopped worrying.

Buying for the wrong pot size. Every duration claim in this category is quoted for an unstated pot. The same 750 ml bottle is fifteen days on a 4-inch pot and three days on a 10-inch one. If a claim does not name a pot size, it is not a claim about anything.

Free things to do before you leave

Move plants away from windows and heat sources. Both light and temperature increase water use, and Virginia Cooperative Extension lists them among the factors that change how much water a plant needs. A plant in the middle of a cool room can easily last twice as long as the same plant on a sunny sill.

Group plants together. The humidity they release raises the local humidity around all of them, which reduces transpiration a little. It also means you only have to set up one watering rig instead of six.

Water thoroughly the morning you leave - all the way through until it drains, then empty the saucer within an hour. Extension guidance is explicit that a container should not stand in water for more than 60 minutes, so a saucer left full is a rot risk rather than a reserve.

Where to start

For a trip of a week or less on indoor plants, start here. For two weeks or more, only a few things genuinely work and we name them. If you want to know whether a DIY rig is a real option, the honest comparison is the page to read.