Introduction
Spring brings a special kind of excitement to the garden as we watch the landscape wake up with fresh green growth. Among the most anticipated arrivals are begonias, known for their lush foliage and brilliant, nonstop blooms that can brighten even the shadiest corners of your yard. At Longfield Gardens, we love how these versatile plants transform porches, patios, and flower beds with minimal effort. Whether you are planting cascading tuberous begonias in hanging baskets or using wax begonias to edge a garden path, timing is everything for a successful season.
Knowing exactly when to move these tropical beauties outdoors is the secret to vibrant, healthy plants. Because begonias are native to warm climates, they are sensitive to the lingering chill of early spring. This guide is designed for home gardeners who want to ensure their plants transition safely from the indoors to the garden. We will cover the specific temperature cues to look for, how to prepare your plants for the move, and how to time your planting based on your local weather.
Getting the timing right ensures your begonias hit the ground running and bloom beautifully until the first frost of autumn.
The Golden Rule for Begonia Timing
The most important thing to remember about begonias is that they are tropical plants at heart. They thrive in warmth and humidity, which means they have very little tolerance for cold. While some spring bulbs like tulips or daffodils enjoy a bit of frost, begonias do not. For these plants, "safe" means the threat of frost has completely passed and the air has stayed consistently warm.
As a general rule, it is safe to plant begonias outside when nighttime temperatures stay reliably above 50°F (10°C). While they can technically survive a night at 45°F, they won't be happy about it. Cold air can stun the plant, causing it to stop growing or drop its leaves. If you wait until the nights are consistently 60°F (15°C), you will often see much faster growth because the plant doesn't have to spend energy recovering from a chilly evening.
Watching your local weather forecast is much more effective than following a specific date on the calendar. Spring weather is unpredictable, and a late-season frost can happen even after a week of beautiful sunshine. If you see a dip in the forecast, it is always better to wait a few more days. Patience is a gardener's best friend when it comes to begonias.
Key Takeaway: Always wait until the danger of frost has passed and nighttime temperatures are consistently 50°F or higher before moving begonias to their permanent outdoor home.
Understanding Soil Temperature
While air temperature tells you when it is safe for the leaves, soil temperature tells you when it is safe for the roots. This is especially important if you are planting begonias directly into the ground rather than in containers. Roots are the engine of the plant, and they need warmth to start absorbing nutrients and water efficiently.
Ideally, the soil should be around 60°F before you tuck your begonias into the garden. If the soil is too cold and wet, the roots or tubers can struggle. In many regions, the soil takes a week or two longer to warm up than the air does. A simple way to check is to feel the soil with your hand; if it feels uncomfortably cold to the touch, it is likely too early.
For gardeners using containers or hanging baskets, this is less of a concern. Soil in pots warms up much faster than the ground. This is why many people find success starting their begonias in containers on a sunny porch before moving them into the garden beds later in the season. For more ideas, explore the Hanging Begonias collection.
Timing Based on Your Growing Zone
At Longfield Gardens, we use USDA hardiness zones to help determine when to ship your plants so they arrive at the ideal time for planting. You can check your location with the Hardiness Zone Map. Begonias are only hardy (meaning they can stay outside year-round) in zones 9 through 11. In all other parts of the United States, they are treated as annuals or "tender perennials" that must be moved indoors for the winter.
- Zones 9-11: In these warm climates, you can often plant begonias quite early in the spring, or even keep them outdoors year-round in frost-free areas.
- Zones 7-8: You are usually safe to plant outdoors in late April or early May, but keep an eye on those sneaky late-night temperature drops.
- Zones 3-6: In cooler northern climates, mid-to-late May or even early June is the standard. It is very common to start tubers indoors in March or April to give them a head start before the weather is safe enough for them to go outside.
Remember that these are general windows. Your specific microclimate—such as whether you live on a windy hill or in a sheltered valley—can also affect your local temperature.
Starting Tuberous Begonias Indoors
If you want flowers as soon as summer begins, starting your begonias indoors is a fantastic strategy. This is particularly helpful for tuberous begonias, which take a little longer to wake up and start blooming. By starting them inside 8 to 12 weeks before the last frost, you give them a "running start" so they are already leafy and strong by the time the weather warms up.
To do this, place the tubers in a shallow tray or small pots filled with moist potting soil. Ensure the indented side of the tuber is facing up. Keep them in a warm spot with bright, indirect light. Once you see sprouts and the outdoor temperatures meet the 50°F night rule, they will be ready for their transition.
Starting indoors doesn't just give you earlier blooms; it also protects the young, vulnerable sprouts from spring rainstorms and hungry garden critters while they are small. The Non Stop Begonias collection is another option for planning a colorful container display.
The Importance of Hardening Off
Moving a begonia directly from a warm, cozy house or a greenhouse into the garden can be a bit of a shock. The outdoor world has wind, direct sunlight, and shifting temperatures that the plant isn't used to yet. To keep your begonias safe, you should put them through a process called "hardening off."
Hardening off is simply a slow introduction to the outdoors over about 7 to 10 days. Think of it like a vacation for your plants.
- Days 1-2: Place your begonias outside in a fully shaded, sheltered spot for just two or three hours during the warmest part of the day, then bring them back inside.
- Days 3-5: Gradually increase the time they spend outside by a couple of hours each day. You can also begin exposing them to a tiny bit of dappled sunlight.
- Days 6-8: Leave them outside for the full day. At this point, if the nights are staying above 50°F, you can let them stay out into the evening, bringing them in just before bed.
- Days 9-10: If the forecast looks clear and warm, they can stay out all night. After this, they are ready to be planted in their permanent outdoor spots.
This gradual process strengthens the plant’s "skin" (the outer cell layers of the leaves) and helps them handle the wind without wilting.
What to do next:
- Check your local frost dates for your zip code.
- Monitor your porch thermometer for three consecutive nights of 50°F+.
- Find a sheltered spot in the shade to begin the hardening-off process.
- Prepare your pots or garden soil with compost for better drainage.
Choosing the Right Spot Outdoors
Once the temperature is safe, the next step in a successful outdoor transition is finding the right location. Begonias are famous for their love of shade, but "shade" can mean different things depending on where you live.
In northern states, begonias can often handle more sun, especially in the morning. In the South, the afternoon sun can be quite intense, so they will perform best in a spot that stays cool and shaded after noon. Wax begonias are generally the most sun-tolerant, while Rex and tuberous begonias prefer filtered light or open shade, like under a large tree or on a covered patio. For more information about Rex begonias, see this Rex begonia growing guide.
Drainage is the other critical factor. Begonias like to stay moist, but they do not like to have "wet feet." This means the water should move through the soil easily. If you are planting in the ground, adding a bit of compost or peat moss can help create the light, airy structure begonias love. If you are using containers, ensure there are plenty of drainage holes at the bottom.
What to Do if a Cold Snap Hits
Even the most careful gardener can be surprised by a sudden cold front. If you have already moved your begonias outside and the forecast suddenly calls for a temperature dip below 45°F, don't worry—you can still keep them safe.
- Move Containers: If your begonias are in pots or hanging baskets, the easiest solution is to bring them into a garage, shed, or entryway for the night.
- Cover Ground Plants: For begonias planted in the soil, you can cover them with a frost blanket, an old bedsheet, or even a large plastic tub turned upside down. Avoid using thin plastic film that touches the leaves directly, as this can actually transfer the cold to the plant.
- Water Lightly: If a cold night is coming, make sure the soil is slightly moist. Moist soil holds heat better than bone-dry soil, which can provide a tiny bit of extra protection for the roots.
Most begonias are resilient. If they get a little chilly, they might look a bit droopy the next morning, but once the sun comes out and the air warms up, they usually perk right back up.
Caring for Begonias After Planting
After you have safely transitioned your begonias outside, the rest of the season is relatively easy. These plants are "self-cleaning," meaning most varieties don't require you to spend time pinching off dead flowers—the old blooms simply fall off as new ones grow.
Watering is the main task. The goal is to keep the soil like a wrung-out sponge: damp but not dripping. In the heat of summer, containers might need water every day, while garden beds can usually go longer. A balanced, liquid fertilizer applied once a month can help keep the foliage lush and the flowers coming all the way through September. For additional guidance, see this begonia care guide.
Safety Note for Pets and Children
It is important to note that begonias contain calcium oxalates, which can be toxic if eaten by pets or small children. While the most concentrated part of the toxin is in the tubers (the roots), the leaves and flowers can also cause irritation to the mouth and throat. When choosing a spot for your begonias, consider placing hanging baskets or high planters in areas where curious pets or toddlers won't be tempted to take a nibble.
Bringing Begonias Back Inside for Fall
Just as we watched the temperatures in the spring to know when it was safe to go out, we have to watch them in the fall to know when it is time to come back in. When the night temperatures begin to dip back toward 50°F in the autumn, it is time to think about the transition.
For tuberous begonias, the leaves will naturally start to turn yellow as the days get shorter. This is a sign that the plant is storing energy in the tuber for next year. Once the first light frost hits the foliage, you can dig up the tubers, let them dry in a cool spot for a few days, and then store them in a paper bag with some peat moss in a basement or closet until next spring. This begonia overwintering guide provides additional storage guidance.
Wax and Rex begonias can often be brought inside as houseplants. Just be sure to check them for any garden hitchhikers (like small insects) before they join your other indoor plants.
Summary of Success
Planting begonias is one of the most rewarding ways to add consistent color to your home landscape. By following the simple rules of temperature and timing, you can avoid the stress of early-season frost and enjoy a lush, flowering garden all summer long.
- Wait for consistent 50°F nights.
- Ensure the soil is warm and drains well.
- Harden off your plants for a week before permanent planting.
- Choose a shaded or partially shaded spot to protect the delicate leaves.
Longfield Gardens is here to help you every step of the way, from choosing the perfect varieties to providing the tips you need for a successful growing season. With a little patience in the spring, your begonias will reward you with a spectacular show of color that lasts for months. For shipping timing by growing zone, review the Shipping Information.
"The beauty of begonias lies in their resilience and their willingness to bloom in the quiet, shaded corners of our lives. When we give them the warmth they crave, they give us a garden that feels like a sanctuary."
For your next gardening project, consider trying a new variety of begonia to see how different foliage patterns and flower shapes can change the look of your favorite shaded spot. Happy planting!
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 damage the root system or tuber. If frost is in the forecast, always cover your plants or bring them indoors to keep them safe.
How do I know if the soil is warm enough for my begonias?
A good rule of thumb is to wait until you are comfortable wearing short sleeves outside in the evening. If you want to be precise, use a soil thermometer to check that the ground is at least 60°F. In most regions, this happens about two weeks after the last frost date. This begonia planting timing guide offers more information.
Why are the leaves on my newly planted begonias turning white or crispy?
This is often a sign of "sunburn" or shock. If a begonia is moved from a dark indoor spot to a bright outdoor spot too quickly without hardening off, the leaves can't handle the intensity of the light. Always transition them slowly over a week to help them adapt to the outdoor environment. The begonia hanging basket guide includes additional advice for introducing begonias to outdoor light.
Do I need to fertilize my begonias as soon as I plant them?
It is best to wait about two weeks after planting to start a regular fertilizing schedule. This gives the roots time to settle into their new home without being overwhelmed. Once established, a balanced liquid fertilizer used once a month will encourage plenty of blooms and healthy leaves.
