Not enough info - outside plants or inside? In pots or in the ground? How long are you leaving them for? If they're out in the ground, they won't need watering this time of year.

Hi Guest,

I'm assuming that you are referring to plants in pots either indoors or out, since, as Bamboo says, garden plants in the ground will not be in active growth and therefore rarely need watering at this time of the year.

I use the Aquidrip water spikes which have a kind of adjustable tap thing on the bottom that allows you to regulate the water flow. The amount of water and size of bottle is obviously dependent on the pots and plants that you have but a 2-litre bottle will comfortably cover all but the very largest things for up to several weeks. If you have a trial run over 24 hours or so you can then figure out the flow rate that will best suit each plant for the period that you need. They really do work well, I must say.

The next step up from that would be a reservoir-fed automatic watering system which will supply half a dozen or more plants at a time via a drip-tube which is fed from a bag that you fill up.

Ecocharlie sell both of these:

http://www.ecocharlie.co.uk/garden-equipment/watering-products.html

Beyond that there are an array of more complex tap-fed irrigation systems which you can self-assemble to any size/length/number of pots that you require. The big down side though is that you have to leave the tap on to feed the system, which is probably not ideal if you're away for a week or so....