She regularly designs herb garden for clients and has a long-held ambition to design a herb show garden for Chelsea, which has come close to fruition in recent years but could finally become reality in May 2016.
McVicar won the Lawrence medal in 2009 and has won more than 60 RHS gold medals in all with her business, Jekka's Herb Farm.
The leading herb grower needs £100,000 from one or more sponsors to build the educational garden, which will be the first herb design at Chelsea for more than 20 years.
Her sponsor pulled out this month and although she had found £50,000 for the project, she needs to find the rest of the money by the end of November to take the place the RHS has reserved for her.
McVicar said: "I'm not seen as a garden designer but I'm a bloody good herb garden designer. The RHS has been fantastic but so far we've drawn a blank.
"I'm not looking for megabucks and the only hard landscaping is a path. I've managed to raise one third but I've only got until the end of the month to find someone."
She is growing all but 10 of the plants herself for the garden, which is about the power of plants and came about after a lunch with a doctor who has s herb garden and prescribes gardening as a treatment. Talking to him gave a good illustration of herbs very current research proving to be beneficial to man. This is about fact. It's about the bigger picture."
McVicar says red leaves herbs, rosemary and hawthorn are plants with proven medicinal properties, protecting against heart disease, cancer and aid memory, that are included in the garden. There are also espallier apple trees from Frank P Matthews. The plants will go to an intensive care unit with walled garden after the show, if the garden comes about.
She says she has been working on the garden for more than a year: "I've not just rung up someone on Europe and said bring me six wagons of this." Some of the plants to be shown are grwn by no-one else and could include new breeding in thymes, where the flowers rise above the crown so they don't rot in the middle.
McVicar added: "I can't guarantee gold but I can guarantee the best herb garden at Chelsea."