How to Grow Asparagus in a Container Garden
Asparagus is one of the few perennial vegetables available to the home gardener. The plant produces shoots, referred to as spears, in spring and early summer. Then it is allowed to produce foliage for the rest of the gardening season, as the foliage helps replenish the roots for next year's growth. Since asparagus lives for so long, planting it in a permanent bed can be problematic if your garden design changes or if you move often. Plant asparagus in containers to free up garden space while still enjoying this vegetable.
Set a planter in an area that receives full sunlight, preferably on the south side of the home in an area that isn't shaded by trees. Use a container that is at least 30 inches deep and 20 inches in diameter. Use only planters that have drainage holes on the bottom.
Mix a soil-less potting mixture with a 10-20-10 analysis, slow-release fertilizer, following the label instructions for exact application rates. Soil-less mixes consist mainly of peat moss and compost, and drain better than soil mixes.
Fill the container to within 8 inches of the rim with potting mix and fertilizer combination. Sprinkle a superphosphate fertilizer at the rate recommended for a single plant on top of the soil.
Set the asparagus crown on top the soil, placing it in the center of the soil surface root-side down. Cover the asparagus crown with enough soil so that the bottom of the crown sits about 6 inches beneath soil level.
Water the container from the top until the excess moisture begins to drain from the bottom of the pot. Asparagus shoots will begin growing within a week. Water thereafter when the top 1 inch of soil begins to feel dry. This may be daily during hot weather.
Fertilize plants once a month beginning in the 10th week after planting. Use a water-soluble, balanced fertilizer at the rate recommended on the package. Fertilize until the asparagus dies back in fall, then resume in spring when new growth appears.
Don't harvest asparagus the first year you plant it; the crown needs time to become established. Starting in the second year, cut off shoots as needed when they reach about 6 to 8 inches long.
Do not plant more than one asparagus crown per container. Asparagus needs plenty of room for the roots to spread.