Snap off tough ends of asparagus and cut the spears into inch segments.
In a saucepan combine the ends of the asparagus, the chicken stock and 3 cups of water. Bring to a boil over medium high heat. Lower the heat to low and simmer for about 15 minutes.
Strain out the solids and keep the broth warm on low heat.
In a 4 quart saucepan, melt the butter over medium heat.
Add the onion and ½ teaspoon of salt. Cook until the onion is softened and translucent - about 9 minutes.
Add the rice and cooking stirring until the edges become transparent - about 4 to 5 minutes.
Add the wine and cooking stirring until it evaporates. Add 3 cups of the stock and cook, stirring. Simmer until it's absorbed - about 10-12 minutes.
Continue to add ½ cup of stock at a time when the liquid is absorbed, stirring. When the rice starts taking longer to absorb the liquid, add the asparagus.
Continue adding ½ cup of stock at a time, cooking until the asparagus is crisp tender about 5 - 7 minutes.
Stir in the parmesan cheese and lemon zest. Taste and add salt and pepper.
Serve with lemon wedges.