My vegetable garden is made from walled beds up to 450mm high (similar to Peter Cundall's in Hobart on the ABC show. This meant bringing in soil and apart from the problems of fertility, lack of water retention etc which is a subject in its own right, because I added mushroom compost ( which breaks down quickly) and also just with settling, the soil level in the beds keeps dropping dramatically. With annual plantings, this is not too much of a problem (apart from cost) as I simply top it up before the new planting and I assume eventually this will stop or at least diminish. However I planted my asparagus crowns 2 years ago before I was aware of the problem and the soil level for these is now 20cms below the bed edge and looks terrible.

I guess I have 3 options and would like to know if anyone has the "right" answer.

1. Simply add soil to the existing plants and act as though I was blanching them as for white asparagus - this is assuming the spears would come up through this depth of soil

2. Lift the plants in winter, raise the soil and replant, Would this mean I would have to wait another 3 years before I could harvest.

3. Discard them and start with new plants and wait another 3 years to harvest.