Plants that can take the heat in the Indiana landscape

Prevent annual plant fizzle in the Indiana summer landscape

When summer’s temps reach the 90s and beyond, many annuals just fade, flop or fizzle. Irrigation systems can be adjusted as needed.

But some gardeners like to hand water. Hand watering can be a peaceful, mind-resting task. It gives you a chance to see up close what’s happening with the plants. Here are some tips.

There are two ways to prevent plant fizzle:

• Select plants that can take the heat.

• Water plants regularly.

Annuals that can take the sun and heat

Hummingbird at lantana.

Lantana

Lantana is at home in a container as it is in the ground. Plants come as upright, sprawling and trailing types. They are no maintenance except watering during dry spells and an occasional shot of water-soluble fertilizer, according to label directions.

Some varieties have single color flowers, such as yellow or white. But many more have tiny flowers of different colors that form the plant’s rounded head. For example some have tiny red and yellow flowers on the head or pink and cream flowers.

The sun-loving lantana is a perennial in other parts of the world, and it has woody-like stems. Pollinators regularly visit the flowers. The seeds heads are toxic.

Queeny zinnia.

Zinnia

Probably one of a gardener’s favorite annuals is zinnia, a joy to cut and enjoy indoors. Zinnias are easy to grow from seed in the ground and transplants are readily available at garden centers. They come in many colors and sizes.

Several newer varieties have more rounded shapes and work well in containers. These varieties also tend to be resistant to powdery mildew or leaf spots, common fungus diseases on zinnias.

Zinnias do best in full sun and with good air circulation. Deadheading, removing spent flowers, keeps them blooming.

Bees Knees petunia.

Petunias

Gone are the days of wimpy petunias. Today’s varieties of this versatile annual tend to be tough, self-cleaning and long blooming. Petunias can be grown in full sun or part shade.

Proven Winner’s Bubble Gum Supertunia (Petunia hybrid) is today’s best-selling variety. Wave petunias, which celebrate their 30th anniversary in 2025, come in many colors and can be used as a seasonal ground cover in the landscape.

If petunias get leggy, cut them back and give them a shot of water-soluble fertilizer.

Victoria Blue Salvia farinacea

Salvia

For a plant with beautiful, showy red flowers, go for one of the gorgeous red annual salvias (S. splendens). The hummingbirds and other pollinators will thank you with frequent visits to the small, trumpet-shaped flowers.

If red is not your color, you can’t go wrong with ‘Victoria Blue’ salvia (S. farinacea). Spikes of blue flowers attract pollinators and persist throughout summer into fall. It’s not uncommon for this plant to winter over and return the following spring. However, don’t plan your landscape around that possibility.

Salvias do best in full sun. ‘Victoria Blue’ tolerates part shade.

Watering tips

When to water?

For plants in pot or in the ground, watering in the morning is best. That doesn’t mean you can’t water at other times if plants need a drink.

How frequently should you water containers?

Plants in containers need to be watered more frequently than plants in the ground. Usually containers can be watered daily or every other day. A lot depends on what the container is made of, where it’s located in the landscape (sun, shade, wind) and which plants are planted.

The best test is your forefinger. Stick your finger in the soil and if it’s dry just past the first knuckle, water the pot. Water until it runs out the base of the pot. If the pot is in a saucer, empty the water after about 30 minutes.

How much water for in-ground plants?

In-ground annuals can get watered every two or three days until established. Once established, water weekly. Water during dry spells. What’s recommended is about 1-inch of water a week. It’s hard to measure that, so consider timing, such as count to 10 or 20 for each plant. If you get a good rain, watering may not be necessary for several days.

How to water

A watering wand with a showerhead nozzle works well for watering in-ground plants and those in pots. The gentle delivery of the water is not likely to wash plants out of their planting hole.

Contact a pro

For guidance on including annuals in your Indiana landscape, please contact one of Holeman’s landscape professionals.