Pick-Your-Own Lavender Farm III

I wrote to you recently regarding setting up a small lavender farm in Grey-Bruce area of Ontario.
I considered your suggestions carefully and I especially liked the idea of the pick your own lavender gardens, including workshops and tours.
I have now created the garden plan and am presently obtaining quotes from landscaping companies to create the gardens. They will be bigger than first expected (about 45' x 97') including paths and central focus with a view to making this attractive as a garden. It will connect to a sunken secret garden.
My plan is to first plant lavender along the sides of the pathways and central area and the following year fill in the rest of the gardens (after I have seen which varieties do best). However, I am not sure of what to do with the vacant land in the meantime since it could become overrun with weeds. Any suggestions on this?

You could plant a green manure cover crop to enhance the soil. Red clover, buckwheat, oats, are all typical green manure and cover crops that help keep weeds down and help to put back nitrogen and organic matter back into the soil. Which cover crop is suitable depends on the time of year; in the late summer, early fall, you may wish to use red clover.
Next year, you plow the crop under and work the soil to get it ready for planting. Using an annual crop such as oats or buckwheat makes it easier to clean up the ground before planting your herb crop. Red clover has the disadvantage that it could come back after plowing.

Also, am I wise to purchase plugs to plant along the pathways or plants since even if I purchase potted plants they won't bloom next year anyway! I know that 'Lady' lavender does bloom the first year but survival in the zone 5 is a bit questionable. I have had one plant for several years but in a very sheltered spot. Is Hidcote the best bet (it has performed well but seems shorter and slow to grow), what about 'Twickle Purple'?

Plugs are by far the least expensive way to establish plants. They take longer because they are smaller in size, but in most situations the difference between plugs and a four inch pot is not that great; meanwhile the cost difference is large.
We do not recommend 'Lady' for commercial production fields, or for your project – mainly for the reason you give. 'Twickle Purple' could work, and also 'Grosso' and 'Provence'. The latter two need excellent draining soil and mulching to survive winters reliably.

The gardens will eventually be surrounded with some cedars and rugosa roses which might offer some protection and also I plan on making the beds somewhat raised and edged in fieldstone.
Any information that you could offer at this stage would be very much appreciated. I really value your input and want to try to pursue this venture correctly.

Cover crops and green manure crops are commonly used by organic farmers. Do a little research and check with organic farming books or with organic farmers in your area for recommendations of the best cover crop to put in for your soil type and season.