Petunia F1 Shake Grapeberry

How do you grow Petunia F1 Shake Grapeberry?

Petunia F1 Shake Grapeberry belongs to the Shake series of F1 multiflora petunias. The series was bred to be naturally dwarf, so the plants stay neat and compact without pinching, and to grow and flower evenly. Grapeberry has cream flowers with purple stripes, and because each Shake colour comes from a single cross, the pattern varies a little from plant to plant. Expect plants about 15–20cm tall and 20–25cm across. Petunias are frost tender, so in the UK they’re grown as half-hardy annuals: raised indoors in spring, planted out once the frosts are over, and in flower from summer until the first frosts of autumn.

When should you sow petunia seed?

• When to sow: Indoors, from late February to April.
• How to sow: Sow thinly on the surface of free-draining seed compost; a little vermiculite or perlite mixed in helps. Petunia seed needs light to germinate, so don’t bury it. At most, give it a very light dusting of vermiculite.
• Warmth: Keep the tray at around 20–24°C, in a propagator or under a clear polythene bag, until the seedlings are up.
• Germination: Seedlings usually appear in 7 to 21 days.

How do you grow the seedlings on?

• Pricking out: Move the seedlings into individual pots once they have two true leaves.
• Growing on: Keep them somewhere cool, bright and frost-free, such as a cold frame.
• Planting out: Harden them off over one to two weeks, then plant out once the risk of frost has passed, usually from the end of May or in June.
• Spacing: About 15–20cm apart in beds, as it’s a compact, upright type. In pots and window boxes you can plant them closer together.

How do you keep petunias flowering?

• Watering: Don’t let the compost dry out. Water the soil rather than the leaves, early in the morning or in the evening.
• Feeding: Every 10–14 days, give a liquid feed high in potash, such as tomato feed. If the plants tire by autumn, switching to a higher-nitrogen feed for the last few weeks can help.
• Deadheading: Pick off faded flowers regularly to keep new ones coming.
• Pinching: Not needed with this series, as it stays compact on its own.

What pests should you look out for?

Aphids on young growth are common and usually nothing to worry about. Slugs and snails are the bigger problem, especially for plants in the ground. Grow your plants on to a good size before planting them out, and protect them with barriers or a wildlife-friendly bait.

Can you keep a plant for next year?

Seed saved from petunias may not come true, so fresh seed each spring is the reliable way to get the same flowers again. If there’s a plant you’d like to keep, take softwood cuttings in late summer and overwinter them indoors on a windowsill.

The Grown Local Verdict “Petunia F1 Shake Grapeberry is a tidy petunia for anyone who wants colour in pots and window boxes without trimming and pinching. Sow it on the surface in spring, keep it warm until it’s up, then feed and deadhead it through the summer.”