Petunia √ó hybrida

Sun, soil, sowing and care essentials

Petunia hybrida seeds thrive in full sun and well-drained, moderately fertile soil. Start indoors with gentle warmth and strong light well before the last frost; seedlings are transplanted only after all frost risk has passed, or direct sown after last frost in mild climates. Surface-sow as light aids germination, keep evenly moist, not wet. Harden off gradually. Growth is compact to medium; space to allow good air flow, following packet guidance. Deadhead to prolong display and pinch lightly for bushier plants. Water thoroughly then allow the top of the mix to dry a little between times, and feed lightly during active growth. Protect from cold snaps and prolonged wet.

• Surface-sow; bright light and 18–22°C encourage prompt, even germination.
• Harden off before transplanting after last frost; avoid cold, waterlogged soils.
• Allow ample airflow; compact to medium plants respond well to light pinching.
• Container suitable: thrives in pots or baskets with free-draining potting mix.
• Ornamental: valued for seasonal colour in beds, borders, and mixed plantings.

How do I start Petunia × hybrida seeds indoors step by step?

Fill clean trays with a fine, sterile seed-starting mix and pre-moisten it evenly. Surface‑sow Petunia × hybrida seeds very thinly (they are tiny), pressing them in without covering. Mist lightly, cover with a clear lid to maintain humidity, and keep at gentle warmth (about 20–24°C) with bright light for 12–16 hours daily. Germination typically takes 5–14 days; remove the cover and increase airflow once seedlings appear. Keep evenly moist, not soggy. Transplant to individual modules at the first true leaves, feed a weak balanced fertiliser, harden off gradually, and plant out after all risk of frost into full sun and well‑drained, moderately fertile soil.

When should I sow petunia seeds in relation to the last frost?

Start seeds indoors well before the last frost, typically 8–12 weeks ahead, so plants are sturdy by planting time. Transplant outdoors only after all frost risk has passed and nights are reliably mild. In mild climates, direct sowing can be done after the last frost once soil is warm and workable, though indoor starting usually yields earlier, fuller displays. In very mild conditions, autumn sowing under protection may be possible, provided seedlings are kept above freezing and in strong light.

What light do petunia seeds need for germination?

Petunia seeds need light to germinate, so do not cover them with mix; simply press onto the surface. Provide bright, consistent light for 12–16 hours daily—south‑facing windows with supplemental light or grow lights placed close above seedlings both work. Maintain a gentle, warm temperature (around 20–24°C) and keep humidity moderate; too much darkness or burial can reduce germination, while insufficient light after sprouting leads to leggy growth. Once up, keep lights close (but not hot) and ensure good airflow to produce sturdy seedlings.

What is the best soil for petunias in containers?

Use a high‑quality, free‑draining potting mix with good aeration; a blend labeled for containers with added perlite works well. Aim for moderately fertile, slightly acidic to neutral conditions (about pH 6.0–6.5). Avoid heavy garden soil, which compacts and holds excess water. Ensure containers have ample drainage holes and adequate volume, especially for trailing forms or hanging baskets. Incorporating a slow‑release fertiliser at planting plus periodic liquid feeds supports sustained flowering without waterlogging or nutrient spikes.

What is the recommended spacing for petunias, and how should I prune them?

Space compact types roughly 20–30 cm apart and more vigorous or trailing types 30–45 cm apart, adjusting to the specific variety and following packet guidance to maintain good airflow. Pinch young plants once or twice, removing the growing tip above 4–6 leaves to encourage branching. Through the season, remove spent blooms (including the seed pod) on non‑self‑cleaning types to prolong flowering. If plants become lanky, shear back by about one‑third, then water and feed; they quickly rebound with fresh growth and blooms.

How do I care for petunias in hanging baskets?

Provide full sun, a large basket with free‑draining mix, and consistent moisture; in hot, dry periods, watering may be needed daily, allowing the top centimetre of mix to dry slightly between waterings. Feed regularly—either a slow‑release fertiliser in the mix plus a balanced liquid feed every 1–2 weeks, or a steady diluted feed—since nutrients leach faster in baskets. Deadhead and lightly trim to keep plants compact and blooming, rotate baskets for even light, and shelter from harsh wind to prevent desiccation and breakage.

Variety descriptions and cultivation guidance are compiled from accredited suppliers and horticultural references. Conditions and results vary by microclimate, soil type, and seasonal patterns; adjust timing to local conditions such as temperature and last frost. Product pages include the most current, item-specific instructions, including sowing depth, spacing, and timing relevant to each lot. All materials are sourced from reputable producers and handled in line with applicable quality and labelling standards.

Further guidance for ornamental seed growers

Petunia hybrida seeds respond best to gentle handling and consistent conditions. Sow on the surface of fine, free-draining media; light assists germination, so only a very light covering, such as a dusting of vermiculite, is advisable. Maintain even moisture with a fine mist and provide warmth around 20–24°C. Start indoors when outdoor soil is still cool, or sow after the last frost when the ground is workable; in mild climates, autumn sowing may be possible. Transplant carefully to limit root disturbance, spacing to encourage airflow and compact growth. Pinching young plants can promote a bushier habit, while regular deadheading supports an extended display. Choose a sunny position with some protection from intense midday heat, and water at the base to keep foliage dry. A balanced, low-salt feed at half strength helps avoid soft, leggy growth. For variety characteristics, sowing notes, and related ornamentals, see SeedsChoice.