Asparagus is best planted in a loose sandier soil for drainage reasons. I can tell you it will do fine in a heavier clay soil as that is what I planted it in. The key is to make sure your bed drains well so the root systems of your asparagus don't sit in water.
There are many ways to care for asparagus. Most methods agree on a pre-spring feeding of a balance fertilizer where NPK or nitrogen, phosphorous and potassium are all equally present. That could be a 10-10-10 or 15-15-15 fertilizer. This is easier to find as a synthetic mix so if you want to go 100% organic, just get as close as that as you can to an equal balance.
Asparagus spears start to grow when soil temperatures hit and stay in the 50 degree F range. I fed mine about a week before spring. You want to give the fertilizer time to get rained on and work its way down into the root system of your clumps. So time your fertilizing accordingly. My video is my twist on a generally excepted way to maintain your asparagus bed.
Good Luck In Your Gardens,
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