Introduction
There is nothing quite like the sight of a begonia in full bloom. Whether you choose the massive, rose-like flowers of tuberous begonias or the steady, reliable color of wax begonias, these plants bring a tropical feel to any porch or garden bed. Bringing that vibrant color into your landscape is one of the most rewarding parts of the spring gardening season.
In this guide, we will help you understand the best timing for moving these tender plants into your garden. At Longfield Gardens, we want to ensure your gardening experience is successful and enjoyable from the very first day. We will cover temperature requirements, how to prepare your plants for the transition, and how to choose the best spot for them to thrive.
Knowing when to move your plants outdoors is the most important step in ensuring a long season of beautiful blooms. Success with begonias starts with waiting for the soil to warm and the threat of cold nights to pass.
The Golden Rule of Begonia Timing
Begonias are tropical plants by nature. They love warmth, humidity, and consistent temperatures. Because of this, they are very sensitive to the cold. Unlike pansies or snapdragons, which can handle a bit of a chill, begonias need truly mild weather to grow their best.
The most important factor in deciding when it is safe to plant begonias outside is the nighttime temperature. While a sunny afternoon might feel warm to you, the ground and the air at night can still be much too cold for a begonia’s delicate roots.
As a general rule, you should wait until nighttime temperatures are consistently above 50°F (10°C). Some of the more sensitive tuberous varieties actually prefer nights to stay closer to 60°F. If you plant them while the nights are still dipping into the 40s, the plants may stop growing or "stall." It can take them weeks to recover from that initial cold shock.
Key Takeaway: Wait until the threat of frost is completely gone and nighttime temperatures stay at 50°F or higher before moving your begonias into the garden.
Understanding Your Local Frost Date
Before you pick up your trowel, you need to know your "average last frost date." This is a date calculated by weather experts that tells you when the chance of freezing weather has mostly passed for your specific area.
In many parts of the United States, the last frost date happens sometime in April or May. However, in northern states or high-altitude areas, it might not be until June. You can find this date by checking with your local university extension service or using a reliable online weather tool.
Keep in mind that an "average" date is just an estimate. Weather can be unpredictable. It is often a good idea to wait a week or two after your last frost date just to be safe. This extra cushion of time allows the soil to soak up more sun and warm up to a temperature that begonias love.
Why Soil Temperature Matters
Air temperature tells you when it is safe for the leaves, but soil temperature tells you when it is safe for the roots. Begonias planted in cold, damp soil are prone to rot. When the soil is warm—ideally around 60°F—the roots can begin to grow and absorb nutrients immediately.
If you aren't sure if the soil is ready, you can use a simple soil thermometer. You can also use the "touch test." If the soil feels uncomfortably cold to your bare hand, it is likely too cold for your begonias. Waiting for that warmth ensures your plants start the season with plenty of energy.
The Transition: Hardening Off Your Begonias
If you started your begonias from tubers indoors or bought them from a warm greenhouse, they aren't quite ready for the "real world" yet. Moving a plant directly from a cozy indoor environment to the wind and sun of the outdoors can cause a shock called "transplant stress."
To prevent this, you should use a process called "hardening off." This is a simple, 7-to-10-day transition period where you gradually introduce your plants to outdoor conditions.
A Simple Hardening Off Schedule
- Days 1–2: Place your begonias in a fully shaded, protected spot (like a covered porch) for two or three hours in the afternoon. Bring them back inside before the sun goes down.
- Days 3–4: Increase their outdoor time to five or six hours. Continue to keep them in the shade and away from strong winds.
- Days 5–6: Leave the plants out all day. If they are a variety that likes more sun, such as wax begonias, give them an hour of morning sunlight. Bring them in at night.
- Days 7–8: If the nighttime temperatures are staying above 50°F, you can leave them out overnight in their pots.
- Days 9–10: Your begonias are now ready to be planted in their permanent outdoor homes.
What to Do Next:
- Check the 10-day weather forecast for any surprise cold snaps.
- Gather your pots or clear your garden beds while your plants are hardening off.
- Ensure you have fresh potting soil or compost ready for planting.
Identifying Your Begonia Type
Knowing which type of begonia you have can help you decide exactly where and when to plant it. While all begonias like warmth, their light and moisture needs can vary.
Tuberous Begonias
These grow from a thick, brown, bulb-like structure called a tuber. They are famous for their huge, spectacular flowers. Varieties like the Double Delight series are perfect for hanging baskets because they have a beautiful trailing habit. These are very sensitive to cold and should be the last ones you move outside. They prefer partial shade and need excellent drainage.
Wax Begonias (Semperflorens)
Wax begonias are the "workhorses" of the garden. They have glossy, waxy leaves and small, abundant flowers. They are more tolerant of sun than other types, especially if they have bronze-colored leaves. While they are still tender, they are slightly more resilient than tuberous types.
Rex and Foliage Begonias
Grown mainly for their stunning leaves, Rex begonias like Pegasus offer incredible patterns and colors. These are often treated as houseplants, but they love a summer vacation outdoors. Because they are grown for their foliage, they need a very protected spot where the wind won't tear their decorative leaves.
Choosing the Right Spot
Once it is warm enough to plant, you need to find the "right place" for your begonias. Getting the location right makes the rest of your season much easier.
Light Requirements
Most begonias prefer "dappled" or "filtered" light. Imagine the light under a tall tree—bright but not direct.
- Shade: Most begonias will thrive in a spot that stays shaded during the hottest part of the day (12 p.m. to 4 p.m.).
- Sun: Wax begonias and some hybrid varieties like the Surefire series can handle more sun, but they still appreciate a break from the intense afternoon heat.
- Indoors to Outdoors: Remember that outdoor light is much stronger than indoor light. Even a "shade" spot outside is often brighter than a sunny windowsill inside.
The Importance of Drainage
Drainage is a term gardeners use to describe how fast water leaves the soil. Begonias have fleshy stems that hold a lot of water. If they sit in soggy soil, those stems and the roots can rot very quickly.
If you are planting in the ground, look for a spot where water doesn't puddle after a rain. If your soil is heavy clay, you can improve it by adding organic matter like compost or finely ground bark. For containers, always make sure there are holes in the bottom so excess water can escape.
Key Takeaway: Begonias love moisture but hate "wet feet." Always use well-draining soil and containers with drainage holes to keep the roots healthy.
Planting Best Practices
When the weather is finally right, planting your begonias is a simple and enjoyable task. Follow these steps for a successful start:
- Prepare the Soil: Loosen the soil in your garden bed or fill your pots with a high-quality potting mix.
- Check the Depth: For wax begonias or plants in nursery pots, plant them at the same depth they were in their original container. For bare tubers, plant them with the "dipped" or indented side facing up. Cover them with only about an inch of soil.
- Spacing: Give your plants room to breathe. Space wax begonias 6 to 8 inches apart. Larger tuberous or hybrid varieties may need 12 inches or more to allow for good air circulation.
- Water Gently: Water the plants right after planting to help settle the soil. Avoid getting water directly on the leaves if possible, as this can lead to spots or fungal issues.
Handling Unexpected Cold Snaps
Even with the best planning, nature sometimes throws a curveball. If you have already planted your begonias and the forecast suddenly predicts a night in the 30s or 40s, don't panic. You can protect your plants with a few simple steps.
For plants in containers, the easiest solution is to move them back into a garage or mudroom for the night. For begonias planted in the ground, you can cover them. Use an old bedsheet, a frost blanket, or even a large cardboard box turned upside down.
Avoid using plastic directly touching the leaves, as it can trap cold and moisture against the plant. Remove the covers as soon as the sun comes up and temperatures begin to rise.
Growing Begonias in Different Regions
Depending on where you live in the United States, your "safe" window for planting will look a bit different.
- The South (Zones 9–11): In these warm climates, begonias can often stay outside year-round. However, the intense summer heat is the bigger challenge. You may want to plant your begonias earlier in the spring so they are well-established before the humidity and heat of July arrive.
- The Mid-Atlantic and Midwest (Zones 6–8): This is the classic begonia territory. Mid-May is usually the safe bet. Keep an eye on those late-spring rainstorms, which can keep the soil cold and wet.
- The North and High Altitudes (Zones 3–5): Patience is key here. You might not be able to plant outside until early June. To get the most out of your short growing season, start your tubers indoors in March or April so they are already blooming by the time it is safe to go outside.
Caring for Your Begonias After Planting
Once your begonias are settled into their outdoor homes, they are relatively low-maintenance. They don't need much to keep them happy through the summer.
Watering Wisely
The goal is to keep the soil "evenly moist." It should feel like a wrung-out sponge. Let the top inch of soil dry out before you water again. In the heat of summer, plants in hanging baskets might need water every day, while plants in the ground might only need it once or twice a week.
Feeding Your Plants
Begonias are "heavy feeders," meaning they use a lot of energy to produce those beautiful leaves and flowers. You can use a balanced, slow-release fertilizer at planting time, or use a liquid fertilizer once a month during the growing season. This ensures the plant has the nutrients it needs to keep blooming until the first frost of autumn.
Safety Note
It is important to remember that many garden plants, including begonias, can be toxic if eaten by pets. Begonias contain calcium oxalates, which can cause irritation in the mouth and stomach of cats and dogs. If you have curious pets, consider placing your begonias in hanging baskets or on high plant stands where they are out of reach.
Troubleshooting Common Issues
If your begonias aren't looking their best shortly after planting, it is usually due to one of three things:
- Yellowing Leaves: This is often a sign of too much water. Scale back your watering and check that the pot is draining properly.
- Crispy or Brown Edges: This usually means the plant is getting too much direct sun or the air is too dry. Move the plant to a shadier spot.
- No Blooms: If the plant looks healthy but won't flower, it might need more light or a boost of fertilizer. Try moving it to a slightly brighter location (but still out of direct afternoon sun).
Key Takeaway: Most begonia problems can be solved by adjusting light or water. Make one change at a time and watch the plant for a week to see how it responds.
The Reward of Patience
While it can be tempting to rush into the garden on the first warm day of April, waiting for the right conditions is the secret to beautiful begonias. By respecting their tropical roots and waiting for consistent warmth, you are setting yourself up for a garden filled with lush foliage and stunning flowers.
Gardening is a journey that teaches us to work with the rhythm of the seasons. When you finally see those first big blooms opening in the summer sun, you will know that every bit of patience was worth it.
Conclusion
Determining when is it safe to plant begonias outside is all about watching the thermometer and knowing your local climate. At Longfield Gardens, we believe that every gardener can achieve professional-looking results by following these simple steps. By waiting for 50°F nights, hardening off your plants, and choosing a well-drained spot, you will enjoy a spectacular display of color all season long.
- Wait for consistent nighttime temperatures above 50°F.
- Harden off indoor plants for 7–10 days before transplanting.
- Select a location with filtered light and excellent drainage.
"The beauty of a begonia garden is a direct result of the care taken during those first few weeks of spring transition."
We are here to support you with high-quality tubers and the practical advice you need to grow them. Take the next step in your gardening journey by selecting a few new begonia varieties to brighten up your shady spaces this year.
FAQ
Can begonias survive a light frost?
No, begonias are very tender and generally cannot survive even a light frost. A freeze will likely turn the leaves to mush and can kill the entire plant. If frost is predicted after you have planted them, be sure to cover them with a cloth or bring containers indoors.
What happens if I plant my begonias outside too early?
If you plant begonias when the air or soil is still cold, the plants will likely stop growing and may enter a period of dormancy. Cold, wet soil can also lead to root or tuber rot. It is much better to keep them in a protected indoor area until the weather is reliably warm.
Should I wait for a specific soil temperature?
Yes, begonias prefer soil temperatures to be at least 60°F. While air temperature is important for the leaves, the roots need warm soil to begin growing. If the soil is too cold, the plant will sit idle and may become susceptible to disease.
When should I bring my begonias back inside for the winter?
You should bring your begonias back inside before the first frost of autumn hits. Most gardeners bring them in when nighttime temperatures begin to consistently dip back down into the 50s. This gives the plants time to adjust to indoor conditions before the harsh winter weather arrives. For timing and delivery by zone, check Shipping Information before ordering.
