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Southport Red Globe Onions

Long Day · Amaryllidaceae

Southport Red Globe is a long-day storage onion selected for medium globe-shaped bulbs with red skin and a crisp mild flavor. It suits northern gardens better than short-day types and is useful for slicing, cooking, and cured storage. Plants stay upright and tidy while bulbing, especially when given full sun and constant moisture. Key facts: 120 days to maturity, 6+ hours of sun, 4–6 " spacing. Container-friendly (minimum 3-gallon pot).

Updated April 19, 2026 · Backed by 2 cited sources
Overview

At a Glance

The essentials first: timing, light, spacing, seed-starting, container fit, and overall size.

Days to maturity
120 days
Sun
6+ hours
Full Sun, 8+ Hours
Spacing
4–6 "
between plants
Seed start
8–10 weeks
before transplant
Container
Yes
3+ gallon pot
Height
1–1.5 ft
at maturity
Planting window

Zone Planting Guide

Switch zones to see whether this plant is a strong fit, what frost timing looks like, and any extra notes worth planning around.

This card updates instantly with viability, frost timing, and any planting notes for your selected zone.

Resilience

Plant Health

Stress tolerance, resistance notes, and the most common problems to watch for as plants mature.

Tolerance
Heat: Moderate Cold: Moderate Drought: Low

Common Issues

Small Bulbs

Cause: Wrong day-length adaptation or crowding reduces bulb size.

Prevention: Match day-length type to region and space correctly.

Weed Competition

Cause: Shallow-rooted onions compete poorly with weeds.

Prevention: Keep beds clean from emergence onward.

Thick Necks

Cause: Too much nitrogen or late irrigation can delay curing.

Prevention: Ease off nitrogen and water as harvest approaches.

Feeding & picking

Nutrition & Harvest

How hungry the plant is, what ripe harvest looks like, and how long the crop keeps after picking.

Feeding
Nutrition
Feeding intensityMedium feeder
RecipesWorm Castings Topdress, Compost Tea
Timing
Harvest

Harvest when 50 to 80 percent of tops have fallen and bulbs have sized fully with papery white skins beginning to dry.

Expected yield0.25–0.6 lbs/plant
Storage90 days — Cure thoroughly, then store dry bulbs cool and well ventilated.
Plant relationships

Companion Planting

Helpful neighbors can support growth or deter pests. Keep antagonistic plants separated to reduce stress and competition.

Avoid planting near
Herb Fennel
What you'll need

Growing Supplies

Based on Southport Red Globe's growth profile -- recommendations matched to this variety's specific requirements.

Drip irrigation / soaker hose kit

Every gardener benefits from putting water at the root zone instead of on the leaves, because drip and soaker systems reduce foliar disease pressure by limiting leaf wetness and soil splash. A quality kit should include a backflow preventer, filter, pressure reducer, and UV-resistant tubing.

Source: Iowa State University Extension; Colorado State University Extension; UMass Extension

Soil test kit

A soil test gives a baseline for pH and nutrient status so gardeners can add only what the soil actually needs. Prioritize a mail-in or lab-affiliated kit whenever possible because extension guidance notes that laboratory testing is more accurate than instant readers.

Source: University of Maryland Extension; Purdue Extension; Montana State University Extension

Quality bypass pruners

Extension guidance favors bypass designs because they make cleaner, closer cuts on living tissue than anvil types. Look for hardened steel blades that can be sharpened, a comfortable grip, and a cutting capacity matched to real home-garden stems.

Source: University of New Hampshire Extension; Iowa State University Extension; Purdue University Extension

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Research

Sources

Reference material and extension guidance used to build this growing guide.

seed_catalog Seeds Nowuniversity University of Minnesota Extension
Internal links

Southport Red Globe Onions Planting Dates by Zone

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