How to Get Lush Petunias

Purchase petunia bedding plants at a garden center or nursery. To grow lush petunias, it's important to start with healthy plants. Look for compact plants with even, green color. Avoid plants with spindly growth or brown or yellowing leaves.

Plant in a spot with all day sunlight for the lushest petunias. Petunias grown in shade are less productive, with weak and leggy growth as the plants stretch to reach the sunlight.

Spread 2 to 4 inches of compost or rotten animal manure over the top of the soil, then add a balanced, dry fertilizer with a ratio such as 8-8-8 or 15-15-15 to the top of the soil. Apply the dry fertilizer at a rate of approximately 1 lb. of fertilizer for every 50 square feet of garden space. Use a shovel or a tiller to work the compost or manure and dry fertilizer thoroughly into the top 10 inches of soil.

Dig a hole for each petunia, allowing 10 to 12 inches of space between each plant. Make each hole deep enough to plant the petunia at the same soil depth it was planted in its nursery container. Place the petunia in the hole, then pat soil firmly around the roots.

Plant petunias in a pot filled with commercial potting mixture if you want to grow your petunias in pots. Add a timed-release fertilizer to the potting soil at planting time. Use the fertilizer according to the recommendations on the label.

Water the petunias immediately after planting. Thereafter, petunias are fairly drought tolerant, but benefit from a deep watering once every week to 10 days during hot, dry weather. Soak the soil deep enough to saturate the root zone. Check potted petunias daily, as potting mixture in pots dries much faster. Your potted petunias may need to be watered daily or every other day during hot, dry weather.

Pinch off the tip of each shoot shortly after planting time, or when the plants are about 6 inches tall. Pinching the tips will encourage each shoot to branch out, creating a fuller, lusher petunias with more blooms. Pinch each stem back to about half its length if the plants begin to look scraggly in midsummer.

Deadhead, or pinch off spent petunia blooms as soon as each flower begins to wilt. Remove the wilted bloom and the stem down to the next bloom, leaf or bud. Deadheading spent blooms is crucial if you want to promote lush growth and continued blooming. If you allow the wilted blooms to remain on the plant, the petunias will divert its energy into making seeds instead of making blooms. Deadheading can be time-consuming if you have a lot of petunia plants, but some newer varieties are self-cleaning and require no deadheading.

Fertilize in-ground petunias with a balanced, liquid fertilizer for blooming plants in midsummer, then repeat every other week. Begin feeding the same liquid fertilizer to potted petunias two weeks after planting time, then repeat every other week. Potted petunias require more fertilizer as the plants are unable to draw nutrients from the soil.