Answer: Much depends on the amount of soil the container holds. The more soil it contains, the more moisture it can hold in reserve for your plants. The type of soil you use is also important. Use a mix with a high percentage of peat moss, or better yet, coconut fiber, which holds moisture better. Burpee sells a brand of coconut fiber called Peat Free that would be useful for this purpose. It's also helpful if you have a self-watering container that has a reservoir you can fill up before you leave your cottage.
If you already have a container in place, such as a half whiskey barrel, you can mix a water holding polymer, such as Burpee's Terra Sorb, with potting soil before planting. This product expands when watered and holds moisture in the soil for plants to use as they need it. With this product in place, you can grow any plant you want if the longest spell between watering is 5 days.
If you want to try it without these additives, grow portulaca, gazania, nasturtium, bellflower (Campanula), livingstone daisy (Dorotheanthus bellidiformis), Scaevola aemula, and ivy geranium. Enjoy!
Q&A Library Searching Tips