Crop type: Asparagus
Asparagus officinalis ‘Guelph Millennium’
Common name: Asparagus ‘Guelph Millennium’
Crop slug: asparagus
This Allotment Pro editorial draft summarises the cited RHS cultivar profile. Check the source and adjust cultivation decisions for local conditions.RHS cultivar profile
1 - Overview
‘Guelph Millennium’ is a vigorous, all-male asparagus cultivar that produces heavy yields of green spears with purple tips between April and June. Bred in Canada, it is particularly tolerant of cold and grows in a wide range of soil types provided drainage is good.
The cultivar has an RHS Award of Garden Merit and is listed as a plant for pollinators. It forms a suckering, deciduous perennial clump whose edible spring crop is followed by green, feathery summer foliage.
2 - Size
- Ultimate height
- 0.5–1 metre
- Ultimate spread
- 0.5–1 metre
- Time to ultimate size
- 5–10 years
Reserve a permanent bed that can accommodate a mature clump up to about a metre high and wide. The plant develops gradually over several years, so avoid disturbing its established crown.
3 - Growing conditions
- Suitable soils
- Sand, loam, clay and chalk
- Moisture
- Well-drained
- Soil pH
- Neutral or alkaline
Choose moderately fertile ground where excess water can drain away. Its tolerance of several soil textures gives growers flexibility, but waterlogged conditions remain unsuitable for the crown.
4 - Position and hardiness
- Light
- Full sun
- Aspect
- South-facing
- Exposure
- Sheltered
- Hardiness
- H5 — hardy in most parts of the UK even during severe winters, tolerating approximately −15°C to −10°C once established
A sunny, sheltered position supports strong spear production. The cultivar's Canadian breeding and H5 rating make it especially useful in colder gardens, although emerging spring growth should still be protected from damaging local conditions.
5 - Colour and seasonal interest
| Season | Flowers | Foliage | Fruit |
|---|---|---|---|
| Spring | — | Green | — |
| Summer | — | Green | — |
| Autumn | — | Green | — |
The edible spears are green with purple tips from April to June, followed by green summer and autumn foliage. An em dash means the RHS profile does not state a colour for that field and season.
6 - Botanical details
- Family
- Asparagaceae
- Native to Great Britain and Ireland
- No
- Foliage
- Deciduous
- Habit
- Suckering
- Name status
- Accepted
Genus
Asparagus includes evergreen and deciduous perennials or subshrubs, sometimes climbing, with tuberous rootstocks. Their stems carry small scale-like leaves and larger leaf-like phylloclades; small white or pinkish flowers may be followed by red berries.
Safety
The young spears are edible when cooked. Wear gloves when picking because contact may cause a skin allergy, and do not eat the harmful fruits.
7 - How to grow
Cultivation
Grow in moderately fertile, well-drained soil in full sun. Plant one-year-old crowns or sow seed directly between March and April. Do not harvest during the first year, take only a half harvest in the second, then begin full harvesting in the third year.
Propagation
Propagate by crowns to preserve the named all-male cultivar. Seed propagation is possible but not advised because seedlings take longer to mature and may not remain male plants, which generally crop more strongly.
Suggested locations
- Wildlife gardens
- Sunny, sheltered edible gardens
- Permanent vegetable beds in colder districts
Pruning
Cut few spears, if any, during the first two years so the crown can build strength. Once the foliage yellows, cut it back to 2.5cm (1in) above the soil.
Pests
‘Guelph Millennium’ may be susceptible to asparagus beetle and slugs. Inspect emerging spears and later foliage for feeding damage.
Diseases
The cultivar may be susceptible to foot and root rot. Reliable drainage helps reduce the conditions that favour these diseases.