"We follow a principle of rotation," Terese said, "In the spring we had peas and harvested them in June. Then we planted corn and soybeans."
Apart from benefiting the soil, Terese explained, rotation is also a form of pest control.
"Pests generally prefer one type of crop," she said with a smile, ""So if we rotate then they effectively become confused, they don't know where to go!"
Planting certain herbs or even weeds in among the crops also reduces the pest problem.
"The pests often prefer these weeds, so they attack them rather than the crop. Knowing where the pests will congregate also makes it easier to collect them," she explained.
But make no mistake, making the transition from conventional to organic farming isn't easy or quick, and Terese said the whole process is a continuous learning experience. She compared it to a regular education in school.
"For the first year we just learned some words. The second year we could write some sentences. By the third year we can write some short articles," and with a laugh exclaimed, "I think I am a graduate now!"
Terese now shares her knowledge through writing articles in a weekly newsletters and last year organized an organic agriculture club. After years of hard work, God's Grace Garden now makes weekly deliveries of organic fruits and vegetables to subscribers in and around Beijing.
And at the end of the day, apart from the health benefits, helping the environment and promoting sustainable agriculture, Yinghui Zhang insists eating organic is also good for the taste buds!
"I can tell the difference in the taste," she said. "Like the carrots we just had for lunch, they were sweet and crispy but also soft enough for kids to munch."
Yinghui Zhang attributes the qualities of the produce to the quality of the land.
"The land here is very fertile," she said, "there are no chemicals, no chemical fertilizer. So the carrots just grow - the best!"