Perennials in our Zone 8 mid-Willamette Valley, artichokes, asparagus, and rhubarb are easy to grow, and their harvests can be enjoyed for many seasons when you consider these simple growing tips.
The best time to plant artichoke starts in the ground is 3-4 weeks before our last frost date (roughly mid-May). Artichokes need exposure to cool temperatures, below 45 degrees F, to trigger flowering.
Plant in a bright & sunny location where the soil has been amended with compost, maintaining soil moisture through the growing season. Give these plants some space to grow as they can get up to 3-5 feet tall and 3 feet wide.
During the growing season, fertilize with an organic all-purpose granular fertilizer, once in early spring and again in early July.
The edible part of this plant is the immature artichoke flower buds that are produced mid-summer into fall; when harvesting the flower head, leave about an inch of the stem. Refrigerate artichokes immediately and wash just before cooking them. Allowing buds to flower may reduce the plant’s vigor for the following year’s production.
Bare root asparagus crowns are what you’ll find at our nursery from late January through March. The asparagus crowns are easy to plant, and much less maintenance than starting from seed. Growing asparagus takes some patience because it needs to be well established before it should be harvested.
Asparagus likes rich deep well-drained soil. When planting the crowns, dig out a trench about 12 to 18 inches wide. For in-ground planting, plant crowns about 5 to 6 inches deep; for planting in a raised bed, plant crowns 12 inches deep. Space crowns 12 to 24 inches apart.
When placing the crown in the trench, situate the crown with the pointy nub upwards and the finger-like roots down and spread out, then cover with about 2 inches of soil. Once they push growth (1-2 inches tall) continue to cover new growth with 2 inches of soil. Stop covering new growth once the trench soil line is met.
Fertilize once during winter by lightly scratching in an organic all-purpose granular fertilizer into the top of the soil.
In the second year, you can cut or snap off tender young shoots that have grown to about 6 inches long in early spring. For the first several growing seasons, only harvest young spears for about 2 to 4 weeks. As the plants age the harvest period stretches to 5 to 6 weeks; check every other day for harvestable spears that are 8 to 10 inches long as they grow fast. Stop harvesting when spears begin to decrease in diameter size.
Asparagus spears grow into tall stems with fine fern-like foliage. Allow the ferns to grow and mature into winter. Once all the stems have yellowed or browned and died back, then cut the ferns down to the ground level. New spears will push up again in early spring.
See How It’s Done
If given deep, rich, moist and well-draining soil, rhubarb will provide your garden with years of enjoyment, in flavor and appearance!
Late winter to early spring, plant your rhubarb crown in a hole that is about 15 inches deep and 24 inches wide, creating a mound in the center to plant the crown on top, being sure not to bury the crown. Space plants 3 feet apart with 5 feet between rows. Fertilize in early spring, as new growth emerges, with an organic all-purpose granular fertilizer.
Rhubarb stalks shouldn’t be harvested until the the second year after planting. A light harvest in the first half of summer, roughly 6 stalks per plant, is recommended. Simply just twist the stalks off the plant and cut off all flower-stalks as soon as they emerge. Once established, 20 stalks per plant over a summer can be harvested.