Elizabeth Perkins, Kevin Nealon, Tonye Patano, Mary-Louise Parker, Justin Kirk, Hunter Parrish and Romany Malco star in Weeds, which is back for a third season. (Supplied photo)

As any gardener will confirm, weeds grow on you.

The same can be said for Weeds, the TV series.

It seems like only yesterday that Weeds, which stars Mary-Louise Parker, was making its controversial debut. A widowed suburban mom who sells marijuana? Scandalous.

But that was a simpler time. It was 2005.

Presently, the third season of Weeds will make its Canadian debut tonight on Showcase (Weeds is in the midst of its third-season run in the U.S. on its network of origin, Showtime).

If you had suggested two years ago that Weeds would last this long, you might have been asked to submit to a drug test. But the series has achieved its strong critical success and modest viewership success for two main reasons:

1) It is very well-acted. Parker is at the forefront, but there is a stellar ensemble cast featuring Elizabeth Perkins, Romany Malco, Kevin Nealon and Justin Kirk, among others. Mary-Kate Olsen and Matthew Modine will join the cast this season, too, but neither of them appears in the episode airing tonight.

2) The writing has been deft enough to prevent the series from becoming a one-trick pony. The mom who sells pot ... yeah, we get it. Luckily, Weeds is more than that. And as groundbreaking as the subject matter was at the outset, the storyline was way darker in the second season than in the first.

As the third season begins tonight, we find Parker's character, Nancy Botwin, exactly where we left her: With multiple guns pointed at her head.

Weeds is able to find humour in just about every situation, but clearly Nancy's path is becoming more dire.

"(Nancy) is someone who has had to function in that (gangster) world in spite of who she is," Parker said. "I think she has an underlying sort of volcanic personality that's not maybe immediately evident when you see her.

"Because she's grieving, she has stifled a lot and it comes out in little spurts. She has a little bit of violence to her. But I like all of those scenes, actually."

Ultimately, this lifestyle choice cannot end well for Nancy Botwin, can it?

"Who's talking about an ending?" series creator and executive producer Jenji Kohan said. "Can it have a happy ending? I guess some people will be happy and some people won't.

"It's a hard life, the life of a drug dealer. But in our research, we met people who have been in business since the '70s and were living a very nice life, with kids in private schools and lovely cover businesses. I don't think there ever will be the happy ending or the tragic ending with Weeds. There always is something in the middle."

As Kohan's initial reaction indicates, Weeds is far from ripe. Unfortunately, one thing that is coming to an end tonight is the hilarious guest-starring role for Zooey Deschanel, who never fails to light up a screen.

Deschanel has been playing Kat, the flighty and flaky ex-girlfriend of Nancy's brother Andy (played by Kirk). Tonight, as bizarre circumstances cause Kat to abandon Nancy's young son Shane (played by Alexander Gould), Kat gives the following heartfelt speech: "We'll meet again," Kat tells Shane. "I'll be older, but I'll still be hot. And you'll be older, and you'll still be the same smart, wise, gentle soul that you are now. But you'll be taller, and I think that you're going to do some really interesting things with your facial hair. I just see it."

It won't be easy to live without Deschanel. Luckily, there's enough going on with Weeds to keep everyone pleasantly medicated.