1. Starych drzew się nie przesadza. Old trees are not to be replanted. Old people should not be uprooted. They should live out their days in a familiar environment.
2. Cicha woda brzegi rwie. Quiet water rips the banks (of a river). The quiet ones are sometimes the most adventurous.
3. Podróże kształcą. Journeys educate.
4. Cudze chwalicie, swego nie znacie. You are praising others' (things or customs), you don't know yours'. You are praising foreign things, and you are unaware of your country's achievements.
5. Potrzeba matką wynalazku. A need is a mother of invention.
6. Głodnemu chleb na myśli. A hungry person's thoughts are about bread.
7. Lepiej późno niż wcale. Better late than never.
8. Pan Bóg nie rychliwy, ale sprawiedliwy. God is not quick, but fair/just. Similar to "You reap, what you sow".
9. Przyganiał kocioł garnkowi. The cauldron critiqued the pot. I understood it about the big one criticising the small one, while doing the same thing. It seems that it is not about the size, but about getting dirty. The full version of the saying is "Przyganiał kocioł garnkowi, a sam smoli" - the cauldron critiqued the pot, but it is sooting too.
10. W gorącej wodzie kąpany. He who had a bath in hot (too hot) water. A quicksilver. Somebody who is quick to react, usually overreact, do something without thinking it trough.
11. Czego oczy nie widzą, tego sercu nie żal. What the eyes don't see, the heart does not regret. Sometimes it is better not to see or know about something.
See also: Polish Proverbs - Part One, Polish Proverbs - Part Two