How to tend a marriage.

As spring approaches, our thoughts turn to planting seeds, tending beds, and trimming weeds. The process requires constant attention and can be grueling at times, but if we stick with it, our efforts will surely blossom.

It turns out that what's good for your garden is good for your marriage.

Whether it's a five-year-old partnership that, like a bush at the mercy of an overzealous hedge trimmer, is cut down, or one that disintegrates after nearly 40 years (a la the Rendells), any union is in danger of dying if it's ignored.

But can the success of a marriage be the result of something as simple as watering and fertilizing? According to Gary W. Lewandowski Jr., associate professor of psychology at Monmouth University in New Jersey, it might be.

Lewandowski may not grow tomatoes, but he knows how to grow a marriage. In fact, he has a name for such a recipe: self-expansion. That's your partner's ability to help you grow as a person. And when it comes to a happy marriage, there's nothing more important, he said.

"When you first start dating someone, the relationship is naturally exciting, challenging, interesting," he said. "You enjoy each other's company. That's self-expanding."

Those feelings might carry a couple through the "honeymoon" phase, typically anywhere from three to seven years of a marriage. But once those years pass, self-expansion starts to dwindle. You can add kids for some interest, but by the 10- to 20-year mark, as kids get older and more independent, a couple without any novelty will wilt. In other words, there is no sweet spot in the timeline of a marriage.

"The only time you're safe in your marriage is if you are willing to keep minding it," Lewandowski said.

One solution, Lewandowski suggests, is to continue to date your mate. Instead of spending Saturday nights on the sofa watching repeats of The Office (which you likely didn't do while courting), head out for some fun.

"Do things you did early on in your relationship," he said. "People date furiously in the beginning . . . then they get comfortable." Take a hot-air balloon ride. Go hiking. Hit the flea market. Sign up for a wine tasting. Just make sure the activity is fun and exciting for both of you. (Note: If he likes monster-truck shows and she doesn't, it won't work.) But Lewandowski does advise couples to get out of their comfort zone: Routine and boredom are marriage pesticide.

For Jackie and Bill Shanahan of Norwood, Delaware County, who have been married more than 15 years, that activity is camping, and has been since they first met. However, the process took some fine-tuning. Bill loved camping under the stars, but Jackie just didn't take to sleeping in a tent. So they compromised. "We got a trailer," Jackie said. "Now we go camping, have the campfire, but I have a place to go into." These days, it's a family affair that includes their two kids.

Although Mindy and Jack Miller adore their 7-year-old son, they believe it's important to do the things they did before they had Aaron - "the things that got us to fall in love," Mindy said. Having a mother who loves to babysit makes it easier for the Mount Laurel couple to check out a new restaurant or catch a show at the Borgata in Atlantic City, but it's those date nights that give them the recharge they need to be involved parents and attentive partners.

Andy and Jill Pritikin of New Egypt, N.J., were so attentive to their jobs as day-camp owners that they barely had time for date nights. But last year, their 15th married, things shifted - both their son and daughter went away to overnight camp for the first time. Andy said he looked at his wife and realized, "Wow, I really do like her a lot!" and recalls how the couple talked more in the first week the kids were away than they had in the five years prior.

"It was enlightening," he said. "I got these inspirational moments." With the daily parental pressures reduced, their honeymoon feeling returned.

Having kids can actually make the glue in a marriage stronger, says Stephen Treat, chief executive officer emeritus and senior therapist at Council for Relationships in Philadelphia, because it raises the stakes in a relationship. But to make the marriage stronger, partners have to talk intentionally and ask the question "How is our marriage?"

"We agree to negotiate with each other," says Josh Stern, who lives with his wife, Kim, and children Noah and Ava in Abington. Early in their 11-year marriage, they learned the art of compromise - navigating their way through the maze of in-laws and newly formed family - which they apply to their relationship now. Also, the couple are intent on not getting divorced, Kim says. Adds Josh, "It's not even a consideration."

Those efforts show they are "blending," or growing as a couple, according to Treat, as opposed to "polarizing."

"The ones that blend make it," he says. "Often the ones who polarize get angry with their partner about the thing they most need in themselves." Essentially, both people in the couple have the same basic needs, but one blocks the other's sunlight, not allowing them to grow to their potential.

Treat also suggests planning time away with your spouse and checking in with each other by sharing "compelling stories" about the day. It can be as simple as telling your spouse some good news that happened at work.

"We send each other e-mails," Jill Pritikin notes. In this digital age, signing e-mails with hearts might be one realistic way for couples to connect.

Or better yet, garden.