Are grapes self pollinating if not I would see the lavender would attract a lot of bees. This would benefit the grapes in pollination.

To the best of my knowledge, grape aren't self-pollinating, so this is the only reason I could figure also. But why lavender in particular? It *is* fragrant and there are lots of flowers, but this is also true of other plants. Oh well. Just wondering.

If it is just a pollination issue then I would imagone alyssum would be an excellant choice as well as it bloom for a long period and would attract pollinators to the area.

I read that growing marigold around tomatoes would be good for the tomatoes. Not only will the marigold repel some insects, but the tomatoes will actually grow better too.

The normal recommendation is 2 to 3 marigolds per tomato plant.