Named after the Brazilian Tupi Indian word for tobacco, the petunia (Petunia x hybrida) shines in smoking hot colors and pastel shades in containers, hanging baskets, window boxes and garden borders. With trailing, spreading and mounding varieties, and straight-edged or ruffled petals, petunias are annual plants that can find a place in any garden landscape, blooming prolifically through summer before dying away in fall. Plant the sturdy young nursery plants once all danger of frost has passed, or grow petunias from seed, sowing them 8 to 10 weeks before planting out.
Grow trailing or spreading petunias, such as the Wave series, in hanging baskets. Place a liner in a hanging basket and poke holes through it, and then gently push the foliage of a young petunia through, leaving the roots on the inside. Place plants at intervals of one every 4 or 5 inches around the base of the hanging basket, then fill it with potting soil and plant petunias in the top. Hang it in a full-sun site and water thoroughly until water runs out of the bottom.
Grow milliflora, trailing and spreading petunias in containers. Place a layer of broken pottery or large stones in the bottom of the container, then fill it with potting soil. Plant petunias in the top, and the sides if there are holes to do so. Move the container to its final, full-sun position, such as at the entrance to a pathway, on a pedestal in a central position, in a garden border or on a patio or porch. Water thoroughly.
Grow Tidal Wave petunias up a south-facing, open garden fence. Hammer tacks into the fence posts at 6-inch intervals up to 2 feet, leaving 1/8 inch protruding. Run garden twine between them, across the fence face, and tie off tightly. Plant petunias 4 inches from the base of the fence, 6 inches apart. As the plants grow, train them up the twine.
Line a garden pathway with grandiflora, multiflora and floribunda petunias. Dig over the soil to a depth of 6 inches, until it's crumbly. Plant petunias 12 inches apart, and 6 inches from the edge of the path. Plants will spill onto the path, so plant farther away if this is likely to cause a problem.
Grow petunias as ground cover in garden beds. Dig out weeds, taking care not to disturb plant roots, and plant petunias in any bare ground 1 foot square or larger. Do not plant too close to low-growing plants that the petunias may swamp.
Grow petunias in full sun sites in well-drained soil. Plant out after the last frost, in late spring or early summer. Water regularly after planting, so that the ground or container never dries out. Apply a 10-10-10 dry fertilizer at a rate of 1 pound per 100 square feet when planting out into the ground. Fertilize again in July at half the previous rate. Fertilize plants in containers or hanging baskets with a liquid plant feed, at a rate of 1 tablespoon per gallon of water, every week or fortnight. Otherwise, follow manufacturers' instructions for fertilizer application rates.
Remove and destroy plants that show signs of disease, such as distorted, shrunken, streaked leaves and deformed flowers. Spread slug pellets if leaves are being eaten.
Remove dead flowers and pinch out growing tips to encourage blooming. This also helps discourage leaf growth at the expense of flowering.