Squash and Marrow Seeds

How to Grow Zucchini & Squash

The essential guide to growing zucchini and summer squash (mostly Cucurbita pepo) from seed; with notes on germination, cultivation, harvest and even kitchen uses.

Main types & their kitchen personalities:

• Zucchini (green, yellow, striped or round) – mild, lightly sweet flesh that stays tender when sautéed, grilled or spiralised. Blossoms fry or stuff beautifully.
• Patty-pan (“button”) squash – scalloped flying-saucer fruit with firmer texture; slice thick for barbecues or roast whole as edible bowls.
• Crookneck / straight-neck squash – butter-yellow skin, creamy flesh and a slight nuttiness; perfect for quick stir-fries, tempura or pickling.

All taste best when harvested young; the smaller you pick, the more the plant keeps producing.

Seeds per gram: 6 – 10 seeds

Germinating temperature: 21 – 35 °C (sprouting in 7–14 days; below 17 °C germination slows or fails).

Feed requirements:

• Moderate.
• Spread 2-3 cm of of compost plus a light dusting of balanced organic fertiliser across the bed and dig/fork in.
• Side-dress with a liquid seaweed or fish emulsion every 3–4 weeks once fruit set begins.

Germination & Seedling Tips:

1. For the earliest crop, sow into 8 cm pots indoors 3–4 weeks before last frost; keep at 22–25 °C.
2. Harden off and transplant when seedlings have at least two true leaves and night lows stay above 10 °C.
3. Direct-sow only after soil reaches 18–20 °C: plant seed 2 cm deep, 2 seeds per spot, thinned to the strongest.

Planting & Spacing:

• Bush zucchini / patty-pan: space plants 50–80 cm apart in rows 80–120 cm apart.
• Semi-vining crookneck: allow 1 m between plants.
• Install drip or soaker hose beneath mulch to keep leaves dry and reduce mildew.

Growing On:

• Water deeply when the top 5 cm of soil dries. Uneven watering leads to blossom-end rot or misshapen fruit.
• Mulch with straw to retain moisture and keep fruit clean.
• Plants are monoecious; if early fruit shrivel, hand-pollinate by dabbing pollen from a freshly opened male flower onto the stigma of a female flower (identifiable by the tiny fruit behind the petals).
• Asa older plants are susceptible to mildew do another sowing around mid-summer to ensure healthy plants and a continuous harvest into autumn.

Common Problems & Fixes:

• Powdery or downy mildew in cool, damp spells – boost airflow by trimming the oldest leaves, avoid overhead watering, spray potassium bicarbonate if required.
• Blossom-end rot – keep soil moisture even and ensure adequate calcium.
• Fruit fly, possums, birds – use exclusion netting or pick fruit young and often.
• Lack of fruit set – plant bee-attracting flowers nearby or hand-pollinate.

Harvesting Notes:

Fruit

• Pick 2–3 times weekly once production starts to ensure plants keep flowering.
• Zucchini: 15–20 cm long (or 8 cm diameter for round types).
• Patty-pan: 4–6 cm across.
• Crookneck: 12–15 cm long while skin is glossy and seeds soft.
• Cut with a sharp knife leaving 2 cm of stem; gentle handling avoids scratches.
• Flowers: Harvest male blossoms mid-morning once fully open, leaving a few to pollinate the females.

Storage & Use

• Fresh squash holds 7–10 days at 5–10 °C in the fridge.
• Eat promptly for best crunch or freeze grated flesh for winter baking.

Slice, grill, pickle, stuff or blitz into soups – zucchini and summer squash are the taste of an Aussie summer, and the more you pick, the more they give!