How can I keep my inside plants watered while I am away for 2-3 weeks?

Try those watering bulbs. You fill them with water and stick them in the soil upside down. They will work for 2 weeks, but not sure about three weeks.

If they are plants that enjoy staying damp, you can place them in your bathtub with a few inches of water in it, providing the pots have openings on the bottom.

I have a house sitter for that length of time, but you can fill your sinks and bathtubs with plants and fill up with about an inch of water. Since it is fall you should get 3 weeks out of it.

drip irrigation on a timer. or plant/ cat/house sitter coming by. personally i like friend coming over to house sit for a bit. turn on and off the lights, play with the drapes. lets any one who drives by know that yes some one is in there.

Poke one of two very small holes in the bottom of a water bottle, fill with water, and place the water bottle on top of the soil in the plant container. The slow leak will keep the plants watered.

My Grandmother used to set her plants/planters in a wash basin half filled with water and it would soak up in the planter as needed. WE were gone 2 weeks and did this also with my herb tower and it was fine!

I've gone in and tended to plants and pets for several neighbors. Maybe you can find someone close or try one of the ideas in this video.

https://www.youtube.com/watch?v=pQc3yENYuSk

If you have a tub large enough to hold your plants, first water each plant well (do not overdue the watering -- just give them a good topsoil watering). Line the tub with layers of newspaper and generously wet the paper. Then place each plant on top of the wet paper and cover the plants with long strips of Saran Wrap -- kind of like making a giant terrarium. Your plants should survive nicely in this environment. Make sure to have natural light in the room and keep the door closed while you're away. this has worked for me. Hope my advice helps. My plants are one of my greatest joys and I treat them with loving care.