Direct-Sowing Zucchini, Sunflowers & Nasturtiums in Alberta

When to plant

Wait for soil at 15°C — usually the third or fourth week of May, after any chance of frost. All three resent cold soil; seeds in cold ground sit and rot. The temptation on the first warm spring day is real but the cost of replanting is high — better to wait 10 days and have plants come up uniformly.

Zucchini and summer squash

One zucchini plant produces 5–10 kg of fruit over the season. Two plants is plenty for most households. Three is “why is everyone avoiding me at the office” territory.

• Plant 2.5 cm deep, 4–5 seeds per hill, hills 90 cm apart. Thin to 2–3 strongest plants per hill.
• Or plant in rows: seeds 30 cm apart, thinned to 60 cm final spacing.
• Pick when fruits are 15–20 cm long — bigger fruit is watery and seedy. Check daily once production starts; fruits go from perfect to baseball-bat in 48 hours.
• Variety picks: Black Beauty (heritage standard), Costata Romanesca (Italian striped, nutty flavour), Eight Ball (round, perfect for stuffing), Yellow Crookneck (summer squash variety, mild and prolific).

Sunflowers

Sunflowers are the easiest dramatic plant in the garden. Plant a row along a fence and you’ll have 2–3 metre giants by August. Birds love the seeds in fall — leave heads up after frost as a free bird feeder.

• Plant 2.5 cm deep, 30 cm apart along a sunny fence line.
• Stagger plantings 7–10 days apart through early June for blooms June through frost.
• Tall varieties may need staking on windy sites. Plant against a fence or wall for support.
• Variety picks: Mammoth Russian (3 m, single huge head, edible seeds), Lemon Queen (multi-head, soft yellow, pollinator favourite), Autumn Beauty (rust-and-bronze blends), Teddy Bear (dwarf 60 cm, fluffy gold heads, great for kids).

Nasturtiums

Nasturtiums are the gateway flower — impossible to fail, edible flowers and leaves, and they bloom from June until hard frost. They self-seed reliably in subsequent years if you let a few plants go to seed.

• Plant 1.5 cm deep, 30 cm apart in rows or as a border. Soak seeds overnight to speed germination.
• Don’t fertilize. Rich soil produces lush leaves and few flowers; poor soil produces fewer leaves and abundant blooms.
• The flowers and leaves are edible — peppery, mustard-like flavour, beautiful in salads or as garnish. The unripe green seed pods can be pickled like capers.
• Variety picks: Empress of India (deep crimson, dwarf), Alaska Mix (variegated leaves, mixed colours), Climbing Mixed (vining, scrambles up trellises 2 m tall).
• Bonus: nasturtiums attract aphids away from other crops — planting them at the edge of brassica or bean beds works as a sacrificial trap crop.

Watering

All three want regular watering once established — about 2.5 cm per week. Mulch around zucchini once plants are 30 cm tall to conserve moisture and suppress weeds in the wide spaces between plants. Sunflowers and nasturtiums tolerate drought once roots are established but produce more flowers with consistent moisture.