Meaning:

You use this proverb to tell someone that he/she shouldn't waste money or there is not enough money to buy something expensive.

If someone says, "Money doesn't grow on trees," he/she means that it is not easy to earn money, so it is valuable, and you have only a limited amount of money. You should be careful how much money you spend.

Example:

A: "Mom, can I buy a new dress?"
B: "We can't afford one now. Money doesn't grow on trees."

Our lab computers are getting old, but we can't afford to buy new ones this semester. Money doesn't grow on trees, you know.

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