When you have a child, they never tell you what the hardest part of being a parent is. Trust me, it’s not the 2 a.m. feedings or the toddler years. Heck, it’s not even the teenage years. What I have learned now with two kids gone and away at college and one in his final years at home is this little secret: The hardest part of being a parent is letting your children leave.

I have gone through it twice. The commencement from high school is intense, more intense than you ever expected. For added sentiment, my daughters graduated in 2013 and 2016 and were given diplomas by my husband as head of the school board. Those two moments, those two hugs after the diploma was handed over, will always stick with me.

But then, I knew the commencements would be powerful. What surprises me are the moments that get you later on, the moments you didn’t expect to carry such punch. And those are the moments that remind you of the journey, the moments that you used to enjoy with your kids and now do alone.

Today one of them happened for me. As many of my neighbors did to celebrate the end of the endless rain, I traveled to Kathy’s Korner for my annual rite of passage, dragging a wagon around and stocking up on flowers to brighten my deck. It was only when I was standing in front of the pansies for two minutes and staring intently at them that I realized I was crying.

You see, gardening was always a biggie for me and the kids. All of them participated, but it really was the work of my middle child and me. We would get flowers, plant them together, brighten the deck while listening to music. As I looked at the pansies at Kathy’s Korner, I guess it hit me — yet again — that my daughter is no longer here to garden with me, but away at college in North Carolina.

Today was not an isolated incident. May and June are an emotional time when you are in my time of life. I know a lot of kids who are graduating from high school this year. Heck, our oldest child graduated from college. Every time I turn around another person is graduating, moving on, starting a new chapter. How did this happen?

For years, I wrote a column in this newspaper. I adored doing it. I chronicled my kids adventures in those years, talking about their experience in my Camp Fire group, or helping with the toy drive at the holidays or playing sports. My favorite column, which people still talk to me about today, was probably when I wrote a list of magical experiences I intended to have with my kids one summer. I only stopped doing the column because my then fifth-grade son begged me to quit.

I am so glad I was able to share those experiences, so glad I have the columns to look back on. It keeps all of the memories fresh and makes me incredibly sentimental to read those old stories.

What busy times they were. When my kids were small, I was running a public relations firm from home (plus volunteering a lot with the kids); it felt like the days were very long. I always felt like I was doing neither motherhood nor profession very well. But I was glad I was able to do it, even though I often dreamed of days in the future when I would be more fully invested in my career again.

Those days came. I am busy and commuting to Seattle each day. My kids are 21, 19 and 16. But the years? My gosh, they flew. It reminds me of that old phrase about being a parent: The days are long but the years are short.

They do fly by. You find yourself attending graduation ceremonies and seeing your daughters get diplomas from their dad. You watch your son, who used to like to hug, grow into a silent teenager. You find yourself wondering where the years went.

Then one day, you find yourself looking at pansies at Kathy’s Korner and missing your daughter so much it hurts.

Yes, May and June are a time of change, of letting go. If you have a kid who is graduating or moving on, my thoughts are with you, as I know how hard it is.

And if your kids are young? Enjoy it. Take them to the nursery. Plant flowers together.

It will make a great memory that you will come back to again many times over the years.

— Lauri Hennessey is the vice president of communications &public affairs for the Woodland Park Zoo in Seattle and the mom of three (almost grown) kids.