Think of outlaws, gardens and Humboldt, and just one plant might pop into your mind.

Well, weed that mental image out of your thoughts, and conjure up instead deep yellow black-eyed Susans, dusky purple smoke bushes, and an exotic Australian pine that's not a pine.

Many of the flowers and trees flourishing at the Humboldt Botanical Garden have been tended and nurtured by jail inmates who volunteer their Fridays to get out from behind bars and grub in the dirt.

"We couldn't do it without them," said David Lemm, work crew coordinator for the botanical garden, which is getting ready for a major fund-raising party on Sept. 10.

"The 215 violators are very good gardeners," said Evelyn Giddings, president of the board of the Humboldt Botanical Gardens Foundation. They're skilled at putting in drip irrigation, fertilizing and countless other common sense gardening chores.

Over the past nine years, jail inmates taking part in the sheriff's alternate work program have fenced in the 44-acre garden site,installed irrigation lines, built trails and amended soil. Last year they put in around 3,500 hours of work, compared with 7,000 hours from other garden volunteers.

The garden hasn't been open much yet -- just 10 a.m. to 2 p.m. on Saturdays -- and that only started in 2010, after years of quiet planting and fund raising. Organizers are hoping to expand those hours before the end of year.

Meanwhile, they're partnering with the sheriff and other public works programs to keep on building and to maintain what they've got.

The partnerships have been good ones, Lemms said, and sometimes last long after incarceration with former inmates volunteering or visiting.

"Several of them have brought their mothers and said, ‘This is what I did when I was in jail.'"