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‘Mary Washington’ Asparagus (Asparagus officinalis ‘Mary Washington’)
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Open-pollinated heirloom perennial vegetable
Asparagaceae
Heirloom edible perennials for vegetable gardens
Pépinière.ca
Common name‘Mary Washington’ asparagus
FamilyAsparagaceae
GenusAsparagus
Speciesofficinalis
CultivarMary Washington
Plant typeVegetable plant
Botanical nameAsparagus officinalis ‘Mary Washington’
‘Mary Washington’ Asparagus (Asparagus officinalis ‘Mary Washington’) is an open-pollinated heirloom developed by the USDA around 1919 to improve resistance to asparagus rust. It produces straight, thick, dark-green spears, often purple-tinged at the tightly folded tip, with a classic asparagus flavour. A planting contains both male and female plants: males generally yield more spears, while females can produce red berries and volunteer seedlings. After harvest, shoots become tall, fine, feathery green stems that recharge the underground crown. Modern all-male hybrids may yield more, but Mary Washington remains valued for history, reliability and reproducible seed.
Choose a permanent full-sun site with deep, fertile, organic-rich and freely draining soil. A pH close to 6.5 to 7.0 is particularly suitable. Plant crowns in early spring in a trench, spacing them approximately 30 to 45 cm apart, and gradually fill the trench as shoots lengthen. Keep the bed free of weeds and water regularly during establishment and after harvest. Spring compost and balanced nutrition after harvest support long-term production. Avoid compacted, waterlogged ground because crown and root diseases can shorten the productive life of an asparagus planting.
Do not harvest any spears during the first year. In the second season, limit picking to one or two weeks; from the third year onward, extend the period gradually through mid-June. Harvest spears at approximately 15 to 25 cm tall before their tips open. Stop when most shoots become thinner than a pencil, then allow all fern growth to develop. After a hard frost, remove completely browned stems. Only young spears are intended for food: red berries are toxic, and stems may irritate sensitive skin. Prompt refrigeration preserves quality because freshly cut asparagus deteriorates quickly.
In the garden
- Exposure
- Sun
- Life cycle
- Perennial
Planting guide
Planting & establishment
Spacing / density
About 100 cm between centers, to be adjusted according to actual clump development.
Planting period
Early spring when soil can be worked
Propagation
Crowns, division or open-pollinated seed
Growing method
'Mary Washington' Asparagus: In spring after the thaw or in early autumn, allowing the roots to establish before the severe cold. For 'Mary Washington' asparagus, regularly check the soil around the root ball: it should remain moist. Water at the base when the surface starts to dry, and adjust the amount of water based on rainfall; this exposure (sun) does not eliminate the need for water. Reserve a permanent spot for asparagus and do not harvest all the shoots from a young plant that is still establishing itself.
Soil and care
Soil & care
Watering
For 'Mary Washington' Asparagus, regularly check the soil around the root ball: it must remain moist. Water at the base when the surface begins to dry and adjust waterings based on rainfall; this exposure (full sun) does not eliminate the need for water.
Soil type
Deep, fertile, well-drained
Fertilization
In early spring, add mature compost and balanced fertilizer according to soil-test results before spears emerge. After the final June harvest, provide a second moderate application to support fern growth that recharges the crown. Avoid excessive rates and keep concentrated products away from young shoots. Proper nutrition supports more consistent spears, although water and weed control remain equally important. Stop late heavy feeding and let the foliage mature naturally before frost.
Seasonal care
In early spring, remove remaining debris before emergence and add compost or balanced fertilizer according to soil needs. Weed carefully because fleshy roots lie near the surface. During harvest, pick 15-to-25-cm spears while their tips remain tight. Harvest nothing in the first year and limit the second season to one or two weeks. For an older planting, extend picking gradually through mid-June, but stop when most spears become thinner than a pencil. After the final cut, fertilize moderately, water deeply and allow every new shoot to form tall green fern growth. Inspect for asparagus beetles, aphids, rust and signs of crown rot. During summer, support stems lightly if wind causes lodging. Never remove foliage while it is green because it feeds the crown. After a hard frost, wait until every stem is brown, cut close to the ground and remove debris from the bed to reduce overwintering pests. Renew mulch afterwards without burying the crown deeply. For best results, keep the bed weed-free and allow green fern growth to feed the crown after harvest. Consistent summer moisture supports stored energy and improves spear size during the following spring. This perennial crop deserves a permanent site because a well-maintained crown can produce for more than fifteen years. Remove only fully browned stems after frost to reduce pests without weakening the crown.
Container growing
Container growing
Recommended pot size
At least 75 litres and 50 to 60 cm deep
Permanent container culture is possible but less suitable than a deep garden bed. Choose a container holding at least 75 litres, preferably larger, approximately 50 to 60 cm deep with generous drainage holes. Use rich, stable and airy potting mix. Set one crown in the centre, cover it gradually and place the container in full sun. Check moisture frequently because large summer fern growth uses substantial water. Add compost in spring and balanced fertilizer after harvest. Pick nothing during the first year and remain very conservative in the second. Afterwards, allow green foliage to develop completely. Protect the container from repeated freezing and thawing without moving it into a warm room because cold dormancy remains necessary. Insulate the walls, preserve drainage and prevent standing water. Cut only fully browned stems after frost. Repot or divide when roots fill the container, recognizing that a disturbed crown may need one recovery season before normal harvest resumes. For best results, keep the bed weed-free and allow green fern growth to feed the crown after harvest. Consistent summer moisture supports stored energy and improves spear size during the following spring. This perennial crop deserves a permanent site because a well-maintained crown can produce for more than fifteen years.
Size, flowering & harvest
Mature height
150 cm
Width / spread
100 cm
Foliage type
Deciduous, fine and feathery after harvest
Growth habit
Upright, then branching and feathery
Edible parts
Young spears only; red berries are toxic
Bloom period
After harvest, unpicked spears become branching stems carrying small yellow-green flowers during June or July. ‘Mary Washington’ produces separate male and female plants. Females may form red berries in late summer containing seed capable of producing volunteer seedlings. These fruits are not edible and may cause gastrointestinal upset. Flowering is visually modest and primarily supports reproduction of this open-pollinated cultivar. Male plants generally direct more energy toward spear production because they do not carry a berry crop.
Fruiting
Red berries on female plants; toxic
Harvest
Spring through mid-June on established crowns
Garden associations
Companion plants & uses
Companion plants
Pair ‘Mary Washington’ with low plants that do not compete with its crown or require deep digging. Chives, parsley, calendulas, nasturtiums and selected spring lettuces can occupy row edges. Preserve a clear circle around every crown so emerging spears remain visible and easy to weed. Avoid shrubs, invasive perennials and root vegetables that require disturbing the soil. These pairings are based mainly on compatible space and care rather than guaranteed pest protection. Keep all companions low enough that air can circulate through summer fern growth.
Garden use
Place ‘Mary Washington’ on the north side or at the back of the vegetable garden so 120-to-180-cm summer fern growth does not shade lower crops. Prepare straight rows 1.2 to 1.5 m apart and preserve a path on each side for harvest, weeding and watering. In spring, dark-green spears provide the area’s first crop. After mid-June, the planting becomes a green feathery screen. Low annual flowers may edge the row, but avoid aggressive roots and deep soil cultivation. Organic mulch suppresses weeds without hiding shoots. Female plants may produce decorative but toxic red berries; a label can remind visitors. Remove unwanted volunteer seedlings or retain a few in a reserved area. A permanent path prevents compaction and simplifies harvest for decades. Wait for foliage to brown completely after frost before cleaning the bed. For best results, keep the bed weed-free and allow green fern growth to feed the crown after harvest. Consistent summer moisture supports stored energy and improves spear size during the following spring. This open-pollinated heirloom deserves a permanent site and can produce for more than fifteen years. Remove only fully browned stems after frost to reduce pests without weakening the crown.
Garden inspiration
Create a heritage ‘Mary Washington’ bed on the north side of the vegetable garden with a central path that allows harvest without compacting crowns. In spring, dark-green spears with purple tips emerge through restrained mulch as a traditional crop. After mid-June, let stems form a feathery green screen in front of chives, calendulas and nasturtiums. A label can record the cultivar’s development era, open-pollinated character and planting year. Observe female plants carrying red berries, then collect selected seed or remove fruit before excessive volunteers develop. In fall, wait for foliage to brown completely before cutting. Add compost around the rows afterwards. This design links harvest, horticultural history and seed independence for many years while reminding visitors that berries are not edible. For best results, keep the bed weed-free and allow green fern growth to feed the crown after harvest. Consistent summer moisture supports stored energy and improves spear size during the following spring. This open-pollinated heirloom deserves a permanent site and can produce for more than fifteen years.
Recipe idea
From garden to table
Rinse young spears, snap or trim the fibrous base and serve them raw, grilled, sautéed or steamed. Refrigerate promptly after harvest. Never consume red berries.
Frequently asked questions
Frequently asked questions
Does ‘Mary Washington’ produce male and female plants?
Yes. ‘Mary Washington’ is open-pollinated and produces separate male and female plants. Males generally direct more energy toward spears and may yield better. Females carry small flowers followed by red berries containing seed that can create volunteers. These berries are toxic and must not be eaten. You can collect selected seed to reproduce the cultivar, although new plants will not be as uniform as a cloned hybrid. Remove unwanted seedlings before the permanent bed becomes overcrowded. This mixed-sex character distinguishes Mary Washington from modern all-male asparagus hybrids. For best results, keep the bed weed-free and allow green fern growth to feed the crown after harvest.
Why choose this cultivar instead of a modern hybrid?
‘Mary Washington’ suits gardeners who value horticultural history, classic flavour and seed-saving potential. Developed by the USDA around 1919 for improved rust resistance, it became a long-standing home-garden standard. Modern all-male hybrids usually yield more, are more uniform and often provide stronger overall disease resistance. Mary Washington is therefore not always the best option for maximum commercial productivity. It remains appealing in a heritage, self-reliant and durable garden where history and open-pollinated reproduction matter alongside yield. Proper culture still allows a dependable spring crop for many years. For best results, keep the bed weed-free and allow green fern growth to feed the crown after harvest.
When can ‘Mary Washington’ first be harvested?
Harvest no spears during the planting year because the crown needs every stem to build roots and stored energy. In the second season, a very light one-to-two-week harvest is possible when plants are vigorous. From the third year onward, extend picking gradually through mid-June. A mature bed may crop for six to eight weeks according to its strength. Stop when most spears become thinner than a pencil, then allow every new shoot to develop green fern growth. This discipline protects future harvests. A weak or recently divided crown may need an additional recovery season before normal picking resumes. For best results, keep the bed weed-free and allow green fern growth to feed the crown after harvest.
Which parts of ‘Mary Washington’ are edible?
Only tender young spears harvested in spring are intended for food. Pick them at approximately 15 to 25 cm tall before their tips open. Tall green fern stems must remain after harvest to feed the crown and are not used as a vegetable. Female plants may produce red berries. These fruits are toxic and may cause gastrointestinal upset. Never eat them and keep them away from children and animals. Sensitive people may wear gloves during prolonged handling because raw shoots or stems can sometimes irritate skin. Correct identification of the spear stage is essential. For best results, keep the bed weed-free and allow green fern growth to feed the crown after harvest.
How can rust and asparagus diseases be reduced?
Plant crowns in freely draining soil and avoid sites where diseased asparagus previously grew. Space plants properly so foliage dries quickly and direct water toward the soil rather than stems. ‘Mary Washington’ has some historical rust resistance, although several modern hybrids perform better. Inspect for spots and premature browning, remove heavily affected growth and clear all completely dead foliage after frost. Regular weeding, balanced nutrition and watering during drought also reduce stress that encourages problems. Do not remove healthy green fern growth prematurely because weakened crowns become less resilient over time. For best results, keep the bed weed-free and allow green fern growth to feed the crown after harvest.
Wildlife and pets
Wildlife & precautions
Reported toxicity
Yes
Supporting wildlife
Small summer flowers may interest certain insects, while red berries on female plants can attract birds. ‘Mary Washington’ is nevertheless grown mainly for edible spears. Berries are toxic to people and should never be offered to animals. Flowering companion plants provide a safer and more abundant resource for pollinators around the permanent vegetable bed.
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