What is best time of the month to plant different plants?

I've never heard of this, Tania. I'm curious to see if anyone else has!

I think that's an old wives take. But to honor your grandmother, I'd follow her wisdom. Happy planting!

Anytime of the month is fine. Your mother's concept of the 15th of each month comes from the right weather conditions of no frost, cool temps, workable soil after Mother's Day. Which generally falls close to the 15th of May. This has been carried over to other months. In a sense it is and is not a myth. There is always the risk of frost around Mother's day and can hurt plants. In one point of view your mother would be correct.

She is planting by the gravitational pull of the moon & it is absolutely true.THis can be applied to killing weeds too. If you just cover them during certain times of month they will grow up and around the barrier other times they won't.People have planted by moon cycles since they began agriculture it only changed because of mass production. Not sure why you would even question her knowledge, learn as much from her as you can before she leaves you.

I live in PA and I have always put plants in after Mother's Day. That time of the year you are usually safe from any frost or freezing rain.

The "after Mother's Day planting" is in reference to no more ground freeze not whether there is any more frost,snow,sleet or anything happening above the ground

it all depends on your zone

Many people used to & maybe still do reference the "Farmer's Almanac" for planting of crops, gardens, and doing other things and may have been in relation to the changes in the moon. Whether true or not, I'd go along with her idea! I remember my grandmother even cutting her hair at certain times using the Almanac as advisor! Here's a link to the Almanac.

https://www.almanac.com/