Julie Maruskin said heirloom plants promote genetic diversity, and they have adapted over time to the area's climate and soil. They are also more consistent from year to year than typical hybrid seeds, she said.
"For so long, people only bought hybrids, which were perfectly red and perfectly ripe and produced a lot in one go," she said. "It was amazing that I had to go ask for a tomato that tasted like a real tomato."
The heirloom gardening class runs from 10 a.m. to noon Saturday, and each participant will receive six free packets of heirloom tomato and pepper seeds.
John Maruskin, adult services librarian, will lead a program about moon gardening from 1 to 2 p.m.
"For thousands of years, people have looked at the phases of the moon," he said. "The idea is that as the moon goes through its various phases from new to full to dark, the gravitational pull affects water levels in the earth."
Gardeners who want to use moon phases should plant leafy vegetables between the new and full moons, and root crops between the full and dark moon, John Maruskin said.
"A lot of people are just sort of interested in it, and it adds another dimension to the gardening," he said. "I just like observing the sky anyhow - that's why I'm interested in this."
Following moon phases is similar to using a farmer's almanac to guide planting, he said.
"It gives you a way to organize your gardening time," he said. "Before there were calendars, people scheduled everything according to the moon."
Some gardeners even look to astrology to guide planting, John Maruskin said, but interpretations can vary. When fire signs Aries, Leo and Sagittarius rule the sky, some say it's a good time to plant spicy things like peppers, onions and garlic. Others say it's a bad time to plant anything because the seeds will burn up.
The moon gardening class is for green thumbs of any skill level, he said.
"The thing about it is, anybody can do it," he said. "It really does sort of give people a chance to get in contact with what the seasons are doing and what the moon is doing, and it gives them a way to schedule their time."
There is still space available in both classes, and anyone interested can register by calling the library at 744-5661.