Ecosystem: a system made up of a community of animals, plants and bacteria and its interrelated physical and chemical environment. The best-laid plans of mice and men are oft ruined by a cat.

Everything was perfectly set in place. The living room furniture was rearranged, the massive propagation bench set alongside the sunny windows, the grow lights suspended from the ceiling. The heating mats were rolled out, plugged in and generating heat in anticipation of the first seeding trays about to be carefully placed there for germination.

“Here we go again,” my girls said, half put out by the disturbance in routine and environment, half anxiously thrilled to witness again the mass birthing of plants that is about to begin.

Before the first seeds could be sown there was a disturbance in our household ecosystem. Harry, our beloved kitty, had sniffed out the new arrangement. He leaped onto the propagation table and, carefully straddling the wire covering, navigated his way to the heat mat. Once there, he curled up in a tidy ball and sacked out for a snooze. He tucked his black nose under his tail – the equivalent of putting up a “do not disturb” sign.

“Sunny and 86 degrees,” Harry’s little kitty mind must have thought, thankful for the warmth after tolerating a winter of miserly people keeping the furnace thermostat at 58 degrees. “Purrfect!”

As he pretended to snooze, I gave Harry a stern talking to. We quickly compromised, as one so often must when coexisting with a cat.

“I’ll give up space at the end of the heat mat if you’ll keep your foraging chompers off the catnip and catmint seedlings,” I said. I let him know in no uncertain terms that his behavior last year – his carelessly meandering through the tender seedlings, his midnight munching on herb leaves – will not be tolerated this year.

I think he understands.

For the last two weeks in March and the first week in April our household ecosystem is thoroughly out of balance. It consists of four people, two cats, one dog, thousands of bitty plants and, at any given moment, 50 or more ladybugs. The people and plants coexist just fine, but the rest of the system often is at odds, competing for heat, space, sun and attention.

Secretly, my favorite part about this time of year is the total respect I get from other members of the ecosystem. Well, “respect” might be painting it a bit too pleasantly. It would be more accurate to say I’m the dominant and driving force in this springtime household ecosystem. The top dog.

OK, OK. In our household, I’m the woman everyone fears.

The dog looks up at me with chocolatey eyes, not daring to step past the threshold into the living room. Her sulky look tells me she wouldn’t dare be disobedient. “Don’t go in there!” my kids promptly tell their friends who come to visit. “Mom will be super mad if anything happens to her plants.” I routinely get the “Whatever you say, honey, that’s fine!” look from my husband.

Starting seeds is a pure act of faith. Against impossible odds, they blindly enter this life with no assurance of the resources they need to grow to maturity. The tender little beings need a strong advocate. I understand this. I understand that as the person who sowed and irrigated them, as the one who released them from their dormancy and cued them to come to life, I’m responsible for being their advocate: “Would you please stop poking at the soil with that turkey feather you found in the yard and let the poor seeds be!” or “Kindly stop breathing on the seedlings. I think they’ll get along just fine without you blowing a gale of carbon dioxide on their little leaves!”

“Yes, Mama. Whatever you say!”

Everybody in this house is so understanding this time of year. Except for Harry, that is. His understanding extends as far as the end of the heat mat. Not, I might add, an inch farther.

Diana George Chapin is the BDN garden columnist. Send horticulture questions to Gardening Questions, 512 North Ridge Road, Montville 04941, or e-mail dianagc@midcoast.com. Selected questions will be answered in future columns. Include name, address and telephone number.