When to Plant Begonias Outside for Stunning Summer Color

Begonias are beautiful flowering plants that can add a pop of color to outdoor spaces like gardens patios and porches during the warm summer months. But knowing exactly when to transplant your begonias from indoors to outdoors is key to helping them thrive and produce their signature showy blooms all season long.

We’ll tell you when and how to plant begonias outside so you can enjoy these beautiful flowers in your summer garden.

Begonias are a large group of flowering plants that come in many colors, shapes, and sizes. They have over 1,800 species. These are some of the most common types grown as bedding plants and in pots:

• Wax begonias – One of the most widely grown varieties wax begonias produce continuous flowers in shades of pink, red, white, and orange throughout the growing season. They have succulent stems and shiny rounded leaves.

• Tuberous begonias are grown for their big, rose-like flowers that can be up to 6 inches across. They come in different colors, like red, pink, orange, yellow, and white, and grow from bulbs. Their leaves are shaped like angel wings and are very pretty.

• Rhizomatous begonias – Valued for their unique foliage, rhizomatous begonias produce colorful leaves in hues like silver, deep green, and reddish-brown. Their flowers are smaller but they bloom heavily in shades of white, pink, and red.

• Cane-like begonias: These are one of the few types of begonias that do well in sun. They can get very tall and have stems that look like bamboo. They have hanging groups of bright red, orange, pink, yellow, and white flowers.

No matter which type you grow, following the right planting schedule is crucial for ensuring begonias reach their full potential outdoors.

When to Plant Begonias Outside

Begonias are tropical plants that thrive in warm, humid conditions. Exposing them to cold temperatures below 55°F (13°C) can damage their growth and flowering. As a general rule, most types of begonias should be planted outdoors only after all danger of frost has passed and nighttime temperatures consistently remain above 60°F (16°C).

Wait Until Soil Has Warmed

Aside from air temperature, soil temperature also plays a key role in timing begonia plantings. Begonias grow best when planted into soil that has thoroughly warmed to at least 65°F (18°C). Planting begonias in cold soil will slow their growth, inhibit flowering, and make them more prone to rotting.

Use a soil thermometer to check the temperature around 4 inches deep. Or simply observe your garden – if your other warm weather plants are actively growing, the soil is likely warm enough for begonias too.

Follow Your Hardiness Zone

Referring to your USDA plant hardiness zone is another simple way to determine the optimal planting window. Here are some general begonia planting guidelines based on hardiness zone:

• Zones 10-11 – Begoinas can be planted outside as early as February or March since frost is rare.

• Zones 8-9 – Plant begonias out in March or April after the last expected frost.

• Zones 6-7 – Wait until early to mid May to transplant begonias when overnight lows stay above 55°F (13°C).

• Zones 3-5 – Hold off until late May or even early June once the soil has thoroughly warmed and consistent warmer weather has settled in.

Keep in mind these are only approximate planting times. Always pay attention to local weather forecasts and only plant your begonias out once sustained warm, frost-free conditions have been established in your area.

Acclimating Begonias for Outdoor Planting

Properly acclimating container grown begonias is a critical step to transition them from indoor to outdoor growing conditions. Here are some tips:

• Place the potted begonias outdoors in a shady, sheltered area during the day over a period of 7-10 days. Bring the plants back inside at night if temperatures are still cool.

• After a week of short, daily exposure to the outdoors, you can start leaving the begonias outside overnight as long as temperatures stay above 55°F (13°C).

• Avoid placing tender begonias in direct sun right away. Slowly increase light levels over a week or two to harden the plants off before planting.

How to Plant Begonias Outdoors

Once the weather has thoroughly warmed up in your area and begonias have been properly acclimated, you can transplant them outdoors into garden beds, containers, or hanging baskets. Here are a few tips for planting:

• Select a site with partial sun to partial shade exposure. Morning sun is ideal for most begonias. Shelter from hot afternoon sun.

• Prepare the planting area with rich, well-draining soil. Mix in compost or peat moss to improve moisture retention.

• Plant begonias at the same level they were growing in their containers. Cover the roots with soil and water well after planting.

• Allow 12-24 inches between begonias depending on their mature size. Plant wax begonias 8-12 inches apart and larger tuberous varieties 18-24 inches apart.

• Pinch back leggy growth after planting to encourage bushy, compact plants.

Caring for Begonias Outdoors

Once your begonias are happily established outside, you’ll want to give them the right care and conditions to promote the most abundant flowering:

• Water whenever the top inch of soil dries out. Increase watering frequency during periods of heat and drought.

• Apply a dilute, balanced fertilizer every 2-3 weeks during the growing season.

• Prune off spent blooms to encourage new flowering. Deadhead wax begonias frequently.

• Monitor for common pests like aphids, whiteflies, and powdery mildew. Treat any issues promptly.

• Prepare to transition begonias back indoors once nighttime temperatures start dropping below 55°F (13°C) in autumn.

Enjoy Maximum Impact from Begonias

By understanding the ideal time and technique for planting begonias outside, you can have these beautiful, tropical-looking plants enhancing your garden beds, planters, and window boxes with months of dazzling color. Pay close attention to your local climate, hardiness zone, and weather forecasts when scheduling begonias outdoors each year. With the right planting schedule and proper care, you’ll be rewarded with a spectacular display of blooms on your begonias all summer long.