Asparagus

Asparagus officinalis

Asparagaceae · asparagus family

Matures: 730–1460 days
Harvest: Over a period · Perennial
Sun: 6–8+ hrs
Spacing: 12 in

Planting window

When to sow, by microclimate — foggier blocks run a different calendar than sunnier ones.

	Jan	Feb	Mar	Apr	May	Jun
Foggy	●	●	●
Sunny	●	●	●

	Jul	Aug	Sep	Oct	Nov	Dec
Foggy						●
Sunny						●

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Foggy	●	●	●									●
Sunny	●	●	●									●

Well-suitedMarginalNot suited

Sunlight

How well it does at each level of direct sun per day.

<2 hrs

2–4 hrs

4–6 hrs

6–8 hrs

8+ hrs

Well-suitedMarginalNot suited

Soil depth

Root room it needs — useful for sizing raised beds and containers.

6–10"

10–15"

15–18"

18–24"

Well-suitedMarginalNot suited

Spacing

Room each plant needs — along the row and between rows — for sizing beds.

In-row: 12 in
Between rows: 36–60 in

Growth habit

The shape it makes in the bed and how tall it gets — what tells you whether to give it a trellis, a stake, or just room.

Habit: Upright
Mature height: 3–5 ft

Stands on its own; the tallest types appreciate a stake in wind.

How to start it

Sow it where it grows, or raise it under cover and set it out — and how far ahead to start the seedlings if it's the latter.

Usually: Direct-sow
Start indoors: 10–12 weeks ahead

Direct-sow

Transplant

Sown straight into the bed it will grow in.

Well-suitedMarginalNot suited

Getting started

How it goes in the ground — how deep to sow or set it, and the soil temperature it needs to wake up. The cold-soil floor is the real limiter for direct-sowing in a foggy SF spring.

Started from: From crowns
Ideal soil temp: 65–85°F
Set depth: 4–6 in

Sprouts between 50–95°F; happiest around 65–85°F.

30°F110°F

IdealWorkable

Pests & diseases

What tends to trouble this crop — what it is, what you'll see, and what to do about it, least-toxic first.

Asparagus beetles are the one pest that defines this crop — they scar spring spears and bleach the summer ferns. The two crown diseases are the reason siting matters more here than for an annual: a bed is in for 15+ years, so Phytophthora crown and spear rot, which follows saturated soil, is the real risk in an SF winter — plant on the best-drained ground you have and resist watering an established bed through the rainy season. Fusarium arrives on infected crowns rather than from your soil, so buy from a reputable supplier and pick resistant varieties (UC 157, Jersey Knight).

Pests4

Asparagus Beetles

What it is: Larvae are dark green-gray grubs about 3/4 inch (9 mm) long when full grown. Asparagus beetle adults may be bluish black beetles with a red prothorax and yellow spots and red borders on wings. Spotted asparagus beetles are reddish orange beetles with black spots.
What you'll see: Adults chew the growing tips of spears in spring leaving brown stains, scars, or blemishes. Larvae may chew ferns, causing them to appear bleached.
What to do: Remove spears promptly. Handpick beetles or wash eggs, larvae, and adult beetles off with a strong stream of water. Clean up debris and remove and destroy ferns by proper pruning in late fall to reduce overwintering sites for adults. Applications of a pyrethrin spray may be effective against larvae when they are young.

Aphids

What it is: Aphids have soft pear-shaped bodies with long legs and antennae and may be green, yellow, brown, red, or black depending on the species and the plants they feed on. A few species appear waxy or woolly due to the secretion of a waxy white or gray substance over their body surface.
What you'll see: Low to moderate numbers of leaf-feeding aphids aren't usually damaging in gardens or on trees. However, large populations can turn leaves yellow and stunt shoots; aphids can also produce large quantities of a sticky exudate known as honeydew, which often turns black with the growth of a sooty mold fungus.
What to do: Before planting vegetables, check surrounding areas for sources of aphids and remove these sources. On the other hand, these aphid-infested weeds can sometimes provide an early source of aphid natural enemies.

Cutworms

What it is: Cutworms are dull brown caterpillars ranging in length from 1 to 2 inches when fully grown. They curl into a C-shape when disturbed.
What you'll see: Cutworms feed on blossoms and leaves of many ornamental plants and attack most garden crops. They clip off seedling stems near or just below the soil level.
What to do: Cutworms are pests mainly in the spring. Destroy crop residues; keep garden weed-free in winter.

Snails and Slugs

What you'll see: Snails and slugs feed on a variety of living plants and on decaying plant matter. They create irregular holes with smooth edges on leaves and flowers by scraping with their rasp-like tongues.
What to do: It will not be possible to eliminate some shelters, such as low ledges on fences, the undersides of wooden decks, and water meter boxes, so make a regular practice of trapping and removing snails and slugs from these areas. The survivors congregate in the remaining shelters, where you can more easily locate and remove them.

Diseases2

Fusarium Wilt on Asparagus

What you'll see: Mature plants infected with Fusarium gradually decline in productivity and growth. Spears are weak and spindly. Reddish brown vascular discoloration, which may extend into the crown, is present at the base of infected stalks. Crowns and belowground portions of stems exhibit reddish flecks or sunken brown lesions.
What to do: Fusarium wilt is introduced on transplants. Once in the soil, little can be done to prevent it from infecting other plants. Plant resistant varieties. If direct seeding, use clean seed.

Phytophthora Crown and Spear Rot on Asparagus

What you'll see: Soft, water-soaked lesions on shoots near the soil line elongate rapidly and become light brown. The affected side of the spear becomes flattened, and the shoot becomes extremely curved and may even collapse. Infected crowns display yellow orange colored tissue that may appear waterlogged and fibrous.
What to do: Most common in wet years. Avoid prolonged saturation of the soil and provide good drainage. Irrigate only as much and only as often as necessary. Plant in Phytophthora-free soil and use disease-free transplants.

Sources

Every figure above is backed by these.

UC Master Gardeners, Contra Costa Countybacks plantingWindow, lifecycle, startMethod · Vegetable Planting Guide for Coastal Regions, calibrated for Sunset Zone 17 (areas directly exposed to San Francisco and San Pablo Bay) — the SF-calibrated calendar for this crop, since neither uc-mg-sanmateo-sf nor the Peirce charts carry an asparagus row. Asparagus entry: 'December - March: Plant crowns.' Grown as a perennial with production lasting 15+ years, hence lifecycle perennial. Recommended varieties UC 157, Mary Washington, Jersey Knight, UC 72. Start method: the entry lists only 'Plant crowns' — the crown is set straight into the trench in the bed it will grow in, which is this dataset's direct-sow (the same treatment garlic cloves, seed potatoes and sunchoke tubers get), and it is the usual route in SF. The foggy and sunny maps are identical here on purpose: this is dormant-crown planting, governed by the crown's winter dormancy rather than by a bolting or heat threshold, so the microclimate split that separates foggy from sunny blocks for leafy and fruiting crops does not apply.
UC Master Gardeners, Sonoma County (Planting Summary)backs daysToMaturity, inRowSpacing, rowSpacing, lifecycle, harvestStyle, startMethod · Vegetable Planting Summary, Asparagus row: days to maturity '2-4 years' — stored as days-to-first-harvest, 730-1460, following the convention rhubarb already set for an establishment period (rhubarb stores 365-730 from 'harvest after 1 year' / 'not for 2 years'). Also 12 in in-row spacing, 60 in between rows (the wide end of the row range), season 'C', 'Perennial.' Notes: 'Harvest 2 years from roots, 3 years from seedlings.' Its Jan-Mar (crowns) date is Sonoma-calibrated and inland, so it corroborates the Zone 17 window above rather than setting it; Start method: this row carries method 'T' and an 'Apr-June (seedlings)' window alongside the Jan-Mar crowns, and the notes give 'Harvest 2 years from roots, 3 years from seedlings' — a seedling route that genuinely exists but costs an extra year to first cut, which is why transplant is rated 'maybe' rather than 'yes' or 'no'. The crown route is what the SF-calibrated sources actually prescribe, so it is the `usual`.
University of Minnesota Extensionbacks daysToMaturity, inRowSpacing, rowSpacing, harvestStyle · Growing asparagus in home gardens: 'Begin harvest two years after planting crowns, and three years after planting seeds' — backs the 730-day (2 year) floor of days-to-first-harvest. Spacing: 'the buds of the crowns are spaced about 12 inches apart' (in-row 12) and 'space the furrows at least 3 feet apart' (36 in, the near end of the row range). Harvest: 'The asparagus harvest season lasts about 6 to 8 weeks' — a bounded spring cutting window, after which the plant is left to fern out and rebuild the crown, so over-a-period rather than continuous.
UC Integrated Pest Management (UC IPM)backs plantingDepth, germination, harvestStyle · Cultural Tips for Growing Asparagus: planting depth for the crown propagule — 'Plant in the bottom of a furrow about 4 to 6 inches deep and 12 inches apart... Cover the crowns with 2 to 3 inches of soil.' (UMN quotes a deeper 6-12 in furrow for colder Minnesota ground; the UC figure is used as the California one.) Soil temperature: 'In the garden, optimum root and fern growth develops with temperatures in the range of 65 to 85 F' — the optimal band. Harvest: no cutting in the first year, spears for only '3 to 4 weeks' in the second season, full 8-10 week harvest from the third year on — a bounded annual window.
UC Master Gardeners, Sacramento County (Germination)backs germination · GN 154 Table 1, Asparagus row: 50/75-85/95 F. The 50 F floor and 95 F ceiling are taken from it; the optimal band is UC IPM's 65-85 F root-and-fern figure instead, which describes an established crown rather than a germinating seed. Listed in the source as a germination temperature — asparagus here is grown from crowns, which sprout rather than germinate, but soil temperature still governs when they wake (same treatment as garlic, whose clove entry cites this table the same way). No germinationDays: the schema's vegetative branch has no such field.
UC Master Gardeners, Santa Clara Countybacks startMethod · Vegetable Planting Chart, Asparagus row: the only method listed is 'Plant crowns', and its From seed to transplant column reads '10-12 weeks' — a real lead time, unlike the 'Not applicable' the chart prints on true direct-seed and set-in-place rows (garlic's 'Plant cloves' row reads that way). So the chart does contemplate raising asparagus seedlings under cover, which is what sets indoors true and startIndoorsWeeks 10-12. The chart's planting MONTHS are South-Bay-calibrated and are not used for timing; per its own region note, the method rows and lead times are location-independent seedling biology and transfer to SF.
UC Master Gardeners, Marin Countybacks soilDepth · Planting & Spacing, Hydrozones: 'Deeply rooting plants include artichokes, asparagus, parsnips, rhubarb and tomatoes.' Asparagus is named outright, so it takes the deep-rooted mapping (18-24 yes, 15-18 maybe, shallower no) — the same bands as rhubarb, which this line also names.
NC State Extension — Plant Toolboxbacks growthHabit, sunlight · Asparagus officinalis entry. Height '3 ft. 0 in. - 5 ft. 0 in.' = 36-60 in; Habit/Form 'Erect' and 'Multi-stemmed' — a self-supporting vertical fern clump, so upright. Light: 'Full sun (6 or more hours of direct sunlight a day)' — the full-sun mapping (6-8 and 8-plus yes, 4-6 maybe, below no).
USDA GRIN Taxonomybacks botany · GRIN taxon 300050, Asparagus officinalis L., family Asparagaceae — the thirteenth family in the dataset, added to PLANT_FAMILIES for this crop.