Christine Barney, the Master Gardener who is leading the project for the Healing Garden in the Ascutney Hospital Windsor, VT has invited to the group to participate in the garden this day.
I went there and I had a very interesting conversation with her, covers, plant rotation and plant companions, she was so generous in answering all my questions. Thank you! Here is what she wrote on Sunday July 25:
Hi, Coralia,
Thanks so much for your help in the garden yesterday.
I wanted to add to my answers for two of your questions yesterday.
1. http://www.botany.com/portulaca.html
The link above should take you to a website that tells of Portulaca, and also lists the more common name for the form apt to show up as a volunteer in the garden: Purslane. Sylvia knows it as Pusley. I wanted to check to see if the commercially available Portulaca was also edible (I've eaten the volunteers in my garden--the plants, that is : ) and it looks like it is as well.
Me: A very helpful information. I am wondering if the weedy wild Purslane who is growing around my tomato plants, are doing its best
2. Companion planting/complimentary planting for legumes (nitrogen fixers) and tomatoes:
I realized as I was in my garden at home, that the concept of planting different areas of the garden in rotation over several years (some people do three, others four years apart before repeating). To incorporate what you were suggesting about having the tomatoes and peas grow together, I realized that when one rotates a crop of peas or beans in the soil one year, and then plants tomatoes there the next year, the presumption is that some of the nitrogen fixed in the soil by the legumes the previous year, and the microbes that allow that to happen, are already in the ground the next year when the tomatoes can draw on that for their needs.
Me: This point sounds to me logical, so if I work with these companions then when the rotation is made, all the 'nitrogen job' is working right there for other plants, who need the N now? Can I think in planting corn there? For me looks like a previous cover plant in the sample of the peas with tomatoes.
3. I can't find anything when I went to search to see if I was remembering correctly about inhibitory effects of tomato plants on nearby plants. I did find that tomato plants can produce some antibiotic compounds and perhaps ones that interfere insects, but not other plants. Sorry to have led you astray on that.
Some perspective on the whole rotation idea, and its possible limitations.
I've been reading a book about plant root systems, which suggests the area covered by vegetable roots is much more extensive than we generally appreciate. This means that what you were suggesting by planting adjacent rows of complimentary plants might work, as their root zones might overlap. The hard part of the strategy you suggested could be then rotating the soil/crop distribution, as it would vary by row, rather than how many people do it by blocks in their garden.
Four groups might be Solanaciae (tomatoes, peppers, potatoes) in one quarter, legumes (peas and beans) in one quarter, brassicas (broccoli, Brussels sprouts, cabbages) in one quarter, cucurbits (cucumbers and squashes and melons) and other crops in the remainder. Planting by block, and then rotating different years, theoretically reduces the chance that pests which specialize in one plant type will be overwintered in an area where they can prey on the same family of plants the next year.
Some people suggest that in usual household gardens, the distances between the blocks is so small relative to how much the pests can move (through the air or through the ground), that the rotation really may not do a whole lot for pest control. It may be more valid for large growers.
Me: That is true, and the monitoring part has an important rol. I have planted tomatoes in one row, and next to them, potatoes. Unfortunately, the potato plants have been infected with colorado potato larvae, tons of those! I was concerned about the tomato of my neighbors, even though I am sure that this colorado potato beetle will never attack tomato plants, but it might attract other pests to the nearby relative. Fortunately, I have detected all these on time, I fixed the problem with some BT - Bacillus thuringiensis, and one of my best pest control: hand picking.
I hope this makes sense. Feel free to send questions if I've been unclear.
Me: Sure! I will.
I don't know if you'll be able to check e-mail from Peru. I'm sure your mother will appreciate your company; I hope she is more comfortable by the time you visit.
Me: I will check my e-mail from time to time. Thank you Tina for your warm wishes.
A friend of mine, Kathy Personnet, has given me a gift, a wonderful set of her creation, Fraglets (R) Art System, withe them I will play with Mom while in Peru.
Mami Lidia and I - January 2008
Mollendo, Perú
The garden is divided into five sections: medicinal, fragance, culinary, everlasting and dye plants. 
The above picture with yellow, bright and fragrant flowers belong to the St. John’s wort (Hypericum perforatum), it is located in the medicinal section of this garden. This perennial shrub grows 12-36 inches tall. The blooming period is from mid to late summer. The dark green leaves have oil glands which look like tiny perforations on their undersides. The name comes from its traditional flowering and harvesting on St. John's day, 24 June.
The past days were so hot, I didn't have the time to visit the plot there. Thanks that on Saturday the rain washed out all the gardens! The photo above shows some weeds, time to get rid of them. 
This is the way how it looks now the space, covered with mulch. I left space for camomille seedlings growing.
The time run so quickly and I needed to left the garden before 1:30pm to watch the FIFA World Cup 2010 Spain vs Holland. It was almost 1pm when I left and I arrived late for the Shakira show :(
