Colin sends Mary to meet Ben Weatherstaff at the door and then asks Dickon to help him to a tree so he can lean on it. They discuss that Colin isn't afraid anymore, and Colin asks Dickon if he's performing Magic. Dickon replies that Colin is the one making Magic, and it's the same kind of Magic that makes things grow. A minute after Colin reaches the tree, Ben comes through the door and wonders irritably what Mary is muttering, but she won't say. She's still saying "you can do it" for Colin to try to make Magic.
By insisting that the Magic that's helping Colin is the same kind that makes plants grow, Dickon credits the natural world with Colin's breakthrough. This again centers his recovery around his engagement with the natural world and suggests that positive thinking is only half the battle: one still needs to accept nature.
Colin commands Ben Weatherstaff to look at him and notice that he's not a hunchback or physically impaired. Ben says that Colin isn't mentally impaired either, as some people believe. Colin says sharply that he's not going to die, and Ben agrees. He asks Colin to sit and then give him his orders. Ben describes the kind of work he does and says that this was Mrs. Craven's garden. Colin says that it's his garden now and orders Ben to keep the garden a secret and come when Colin asks for him. Smiling, Ben says he hasn't been inside the garden in two years, but he used to climb over the wall occasionally to prune the roses. He shares that Mrs. Craven made him promise to take care of her roses and notes that caring for them with his rheumatics will be easier now that he can use the door.
By revealing some of these secrets to the children, Ben acts as a link to the past and to Mrs. Craven. Keep in mind that Colin probably hasn't heard much about his mother aside from the fact that she died; this means that through the things that Ben says about her, Colin will be able to gain a better understanding of who his mother was and in doing so, will be able to come to terms with her death. By claiming the garden as his own, Colin chooses to follow in his mother's footsteps and dedicate himself to nature and happiness.
Colin grabs Mary's abandoned trowel and starts to scratch at the ground. Dickon, Mary, and Ben Weatherstaff watch with interest and after a minute, Colin remarks in broad Yorkshire that he's walking and digging on his first day in the garden. Ben laughs and offers to get Colin a rose so he can plant something. Very soon, they settle the potted rose in the ground and water it. Colin asks Dickon to help him stand so he can watch the sunset, which he says is part of the Magic. Colin laughs as the sun goes down.
Planting this rose becomes a way for Colin to symbolically plant himself in the garden and align himself with his mother. This reinforces the garden's role as a motherly nest of sorts, as it'll be the safe, secluded place where Colin and Mary can grow, play, and develop with the help of parental figures like Ben and Mrs. Craven's spirit.