Vegetable · Brassica-head

Waltham 29 Broccoli

Brassicaceae

Waltham 29 is the most widely extension-cited open-pollinated broccoli — a cold-tolerant, reliable fall crop variety developed by the University of Massachusetts. Produces a large central head (4-8") followed by 3-6 weeks of side shoot production after main harvest. 75-90 DTM from transplant (longer than Calabrese-type hybrids). Referenced in Cornell, OSU, Penn State, and UC Davis extension guides as the baseline home garden broccoli. Central head of tightly packed flower buds plus 3-6 weeks of side shoot production after main harvest. Most forgiving of the heading brassicas. Harvest main head before ANY yellow shows — once buds separate, quality drops rapidly. Cut with 6-8 inches of stem. Side shoots are a major second harvest. Heads grow best at 60-70°F; temps above 80°F cause loose, seedy, bitter heads.

At a Glance

Days to Maturity

75–90 days

Sun

6+ hours

6-8 hours full sun

Spacing

16–24 "

Seed Start

4–6 weeks

before transplant

Container

Yes

5+ gallon pot

Height

1.5–2.5 ft

Zone Planting Guide

Your USDA Zone:

Growing Guide

Germination

Germination Time 5–10 days

Optimal Temp 75°F

Seed Depth 0.25"

Transplanting

Harden Off 7–10 days

Watering

Weekly Water 1–1.5 "

Needs Moderate-high

Soil

pH Range 6–7

Soil Type Rich, well-drained, high organic matter

Resilience

Heat: Low Cold: Medium

Common Problems

hollow-stem

Cause: Boron deficiency, rapid growth, wide spacing, excess nitrogen. Multifactorial.

Prevention: Liquid seaweed foliar spray. Avoid over-fertilizing.

yellow-buds

Cause: Harvested too late. Buds separating.

Prevention: Harvest when head is tight, before any yellow shows.

Nutrition

Feeding Intensity Heavy feeder

Harvest

Tight green head, no yellow buds showing. Head 4-7 inches diameter.

Storage 14 days — Refrigerate. Not practical for root cellar.

Sources

university UMD Extension — Growing Broccoli university USU Extension — Broccoli university Utah State University Extension — Broccoli in the Garden (PDF) university Iowa State University Extension — Growing Broccoli in the Home Garden seed-catalog Johnny's Selected Seeds — Broccoli Key Growing Information

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Waltham 29 Broccoli Planting Dates by Zone

Planting dates for Waltham 29 Broccoli vary by USDA hardiness zone. Select your zone below for frost dates, start-indoors timing, and a full monthly planting calendar.

Zone 5A Zone 5B Zone 6A Zone 6B Zone 7A Zone 7B Zone 8A Zone 8B Zone 9A Zone 9B

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