It was jilly's last day in the green house. summer was coming to an end and so was the growing season. school would be starting next week and the fall plants were well enough along to allow mrs. t. to manage the greenhouses herself. as jilly worked the plants for the last time, she tried to focus on the new school year instead of the details of the greenhouse. it had been a hard, hot summer, but jilly was not ready for it to be over. jilly moved down the tables, tucking a stray hair behind her ear with a gloved and already dirty hand. she'd repotted the last of the rosemary plants and mixed a new batch of potting soil already. mrs. t. now had enough potting soil to last her through september. jilly looked at a couple of maiden-hair ferns that were beginning to yellow in their small pots. she loved their lacey fronds and had grown concerned over the last few days that they needed repotting or a boost of fertilizer. she had also worried that she would continue to find chores that needed doing, plants that needed , right up until the minute she left today. she hated unfinished things. she hated details not being tended to. the sun had been above the trees and blasting the greenhouse for a good hour now. jilly listened for the familiar whirr of the automatic vents opening. when the greenhouse reached a certain temperature, the vents would open automatically. the vents would have a cooling effect for an hour or so, and then no amount of breeze would put a dent in the heat. mrs. t. often claimed jilly must be part reptile as she was able to work longer in the greenhouse than anyone else. the heat just didn't bother her. in fact, jilly often looked forward to the warmth of the greenhouse and feeling the heat seep into her bones. it felt good to her, but she understood others who found it hard to breathe in 100 degree temperatures. jilly heard the greenhouse door bang, and looked up from her ferns to see mrs. t. walking down the aisle with a tray of young plants. mums, jilly supposed, the flowers everyone wants for fall. she had mrs. t. take cuttings and plant the small stems in new pots. they were doing nicely from the look of things. "we will keep these in here for now," said mrs. t. "they are getting too much rain outside." it had been a rainy couple of days. jilly knew, as well as anyone, that overwatering could kill potted plants quickly. "do you remember when i overwatered those mint plants? " jilly asked mrs. t. "i used to think no one could kill a mint plant," mrs. t. said, laughing. "well i am full of surprises, apparently," jilly replied. jilly remembered the sad green plants that just kept looking more and more wilted no matter how much water she gave them. it was a beginner's mistake, and jilly had been so embarrassed for making it. "that you are," replied mrs. t. "but i know you learned a lesson you won't ever forget." "of course. herbs like their roots damp, not flooded," jilly answered. "well that is not the lesson i was thinking of," mrs. t. said. jilly wondered for a minute what the lesson could be. she straightened the rows of geraniums in front of her, picking up one or two to check for aphids under the leaves. it had been a summer full of lessons, some especially hard for a girl who thought she knew a lot about plants. she breathed deeply the warm, humid air. she hated the cooped up feeling of air conditioned air, the feeling of being cut off from the sun. she knew school and the library would offer only these uncomfortable feelings and little time to spend in the sun or with plants. she had come to understand this over the summer—her need to be around growing things was huge. "i'm not sure, mrs. t." she said, "i've learned so much this summer. i couldn't possibly say what you are thinking." "you did learn many lessons, jilly. you knew so much when you started. you've gone farther than any other assistants i've had. i will miss you." "and i will miss you," jilly replied. " you for the opportunity and the job." jilly watched mrs. t. put the tray of mums down on the center row of tables. wearing her familiar brown apron, mrs. t. looked just as she had on jilly's first day. "my pleasure, of course, dear," mrs. t. replied. "my hope for you, as for all my assistants over the years, is that you will learn as much about yourself as you do about growing plants." recalling her thoughts all morning, about what she enjoyed about her summer job, jilly realized she knew much more than just how to not drown the mint. read this line from the narrative: school would be starting next week and the fall plants were well enough along to allow mrs. t. to manage the greenhouses herself. what is the main purpose of this sentence in the story?