How to Get Petunias to Last Throughout Summer

Petunias are annual flowers available in many different varieties, colors and shapes. The trick in the home garden is to get them to last throughout the summer. Follow these tips to grow brightly colored petunias that will bloom throughout the warmest months.

Abundant Varieties of Petunias

The so-called old types of petunias are multiflora and grandiflora. Multiflora petunias - as the name implies - flower more freely and tend to tolerate some adverse heat and weather conditions than grandiflora. In size, multiflora varieties have blooms from 1.5 to 3 inches in diameter, compared to 3 to 4-inch diameter grandiflora petunias.

Newer varieties of petunias are those classified as spreading-type plants. Low-growing spreaders reach heights of 6 to 12 inches and can be used as ground cover or in hanging baskets in full sun. Many of the Wave petunias—which have flowers in colors of pink, rose, misty lilac, lavender, blue and purple—grow 24 to 30 inches wide and 8 to 10 inches tall.

Consider the many varieties of petunias: available as singles, doubles, petunias with contrasting edges (called picotees), striped ones, veined, trailing, dwarf, tiny blooms, medium-size blooms and large blooms.

What Petunias Like

To proliferate, petunias aren’t too picky, but they do need full sun. They also like a well-drained, slightly acidic soil. Add organic manure when they are first set into the ground. Fertilize weekly with an all-purpose fertilizer.

Many gardeners find success with getting petunias to bloom all summer by adding water in between regular irrigation periods. This is especially true during the heat of summer in July and August when many petunias become spindly and die out.

Tips to Encourage Petunias to Continue Blooming

Each gardener who grows petunias has their own techniques that have proven useful in maintaining summer blooms. Here are some worth considering:

• Watch the weather forecast and plan accordingly.
• Water petunias early in the day.
• Cut back to the newest set of leaves on each stem. Do this in the cool evening.
• Pinch off blooms after they’re spent, a practice known as deadheading. This will encourage the plant to bloom again.
• Pinch out the very first flowers before they begin to bloom. This makes seedlings branch out. Plants will then produce more flowers and larger blooms with deeper color.
• When petunias are done flowering, prune them back. They will grow and bloom again in the same season.
• Stagger plantings of petunias. Some are early bloomers, while others are so-called perennial bloomers (the Colourwave variety) that last 6 to 9 months.
• Keep mulch away from stems of petunias.
• For hanging baskets, make sure pots have adequate drainage. Place small stones or pebbles in the bottom of the pots to avoid soil leaking out.
• Move hanging baskets to an area where they only receive morning sun, as afternoon sun causes them to dry out and droop.

Try experimenting with different types of petunias as well as growing some from seed and setting out some color flats from the nursery. The Colourwave, for example, is a spreading/cascading variety that can take the place of up to 10 annual petunias – and lasts from 6 to 9 months.