12 August 2009
In The Garden With the Fluvanna Master Gardeners
By Irene C. Burke - Fluvanna Master Gardener
Fluvanna County Extension Office: 434.591.1950
The Bard of Avon held "whats past is prologue" and so it is with asparagus. Its origins set the scene for long-term health: preferences for pH, site, soil, culture and eventual culling.
Eurasia claims asparagus first, the ancient Macedonians cultivating it along its sandy limestone shores. I expect asparagus graced Turkeys emerald coast where St. Paul trod the dusty paths of Ephesus. From their travels, the English brought asparagus home to a shorter growing season but similar soil, thence to Virginia. At Monticello, Jefferson cultivated a few square plots of asparagus, where cultural practices remain unchanged. This native to sandy loam, however, wants Virginias piedmont clay sweetened and lightened.
Asparagus thrives with a pH of 6.0 to 7. Beware - a lower pH, more acidic soil provides a welcome environment for fusarium fungi, not a good thing. One gardening friend secures a stable source of lime in a bed beside a concrete retaining wall, that slowly leaches sweet alkaline.
Achieve a similar effect with a raised bed of two courses of eight by four, 8"x8"x16" hollow, concrete blocks. Site the bed parallel to prevailing winds, to help the mature fronds support one another, but set the bed apart from the rest of the garden, to make room for the ferny summer growth. Where plate-like layers of schist underlie thin clay, your raised bed is the best response to asparagus requirements.
Soil preparation for March planting begins 12 to 6 months prior, with a 50/50 ratio of coarse sand to piedmont clay mixed with 8" of equal amounts of bone or blood meal, compost, leaf mold, manure and wood ashes. Dig as deeply as the site allows. Frequently fluff in, additional organic matter until winter temperatures create a frozen earthen crust.
Thorough soil prep almost guarantees healthy plants, 15 to 20 years of bountiful harvests. Choose the Jersey Knight cultivar, for both immediate use, and freezing and canning.
Trench the bed to a depth of 12" with the soil heaped to the sides. Set year-old crowns on 2" mounds at the trench bottom; cover with 2" to 3" of soil every 2 weeks until the trench is filled. Water gently if spring rains fail to arrive.
Hand pull weeds to avoid injuring spear tips. Side dress with compost, to suppress weeds, and to sustain nutrients throughout the growing season.
Build up a supply of cardboard rolls for cutworm barriers. Insert to a 1" depth around emerging spears - a tedious but effective measure to prevent these munchers from ruining your salad days.
When autumn frosts yellow the ferns, cut to 2" stubs. Mulch to 3" with mixed organic matter - compost, leaf mold, manure, shredded leaves.
Cull in the third year. Note that planting depth has no negative affect on yield, producing thicker, though fewer spears. Shallow plantings, however, encourage earlier harvests with a risk of frost damage.
With its counter-intuitive tenderness factor, youll find that the thicker the spear the softer the texture. Asparagus fibrous outer covering on thin young spears imparts a stringier tougher bite. Thick or thin, the earliest yield of the season is the most tender.
For fancy white asparagus create a barrier that blocks the light but not the growth - mulch, pots, boxes. Was ever something so sophisticated, so easy?
Tip of the Week
In the July issue of Geology, researchers reported that erosion is a good thing when symbiotic fungi like P. involutus, break down rocks, making minerals like potassium, available to plant roots. You can see P. involutus, in the white threads of leaf mold and mulch. Incorporate leaf mold in new planting holes and side dress established ornamentals with composting mulch.