When I planted our citrus trees, I was well aware of the need to keep the grass away, so it doesn’t compete with the shallow tree roots. So I lay down a thick layer of bark mulch (being careful to keep the lower trunk clear).

Some time later, I read through the  Introduction to Permaculture by Bill Mollison. It highlights the benefit of “companion planting” out a whole under-story of plants under citrus trees, increasing productivity and actually helping the trees.

This is what seems most applicable to the urban garden:

• spring bulbs
• comfrey
• dandelion
• globe artichoke
• fennel
• dill
• tansy
• carrot
• catnip
• daisy
• nasturtium
• flowering ground covers

I’ve started with planting out some nasturtium seeds (which produce edible flowers and leaves), as well as dill. I’ll probably add fennel and comfrey down the track…