Should I cut every asparagus spear in our 3-year-old bed, or just the fat ones?
Harvest them all for no longer than three weeks, then stop picking, add some compost, and let the spears go to fern. As plants get older, spears should become more uniformly thick and can bepicked for longer. Cut with a sharp knife or snap spears off, but don't tug them out or you might damage the plant. You need at least 10 plants for each family member for a decent harvest.
What's the difference between a plant genus and a plant species?
Plants are divided into various ranks for scientific purposes, but most gardeners need only be concerned with the genus and species. The genus (a noun, started with a capital letter) comes first, before being further classified by the species (an adjective). For example: Pinus radiata, Rosa rugosa, and Mentha spicata (or spearmint, the one we use for mint sauce). Swedish botanist Carl Linnaeus devised the classification system in the 18th century, and names are written in Latin.
