Introduction
There is something truly special about the moment those first begonia sprouts emerge, promising a summer filled with lush, velvet-like leaves and brilliant flowers. Whether you are looking to brighten a shady porch with hanging baskets or add a splash of color to a quiet garden corner, begonias are one of the most rewarding plants you can choose. At Longfield Gardens, we want to make sure your gardening experience is as enjoyable and successful as possible.
This guide is designed for anyone who wants to know exactly when to move these tropical beauties into the garden. We will cover the specific temperature requirements, how to read your local weather cues, and the best ways to transition your plants from the indoors to the great outdoors. For more on begonia placement, see our guide on where begonias grow best. By focusing on a few simple timing rules, you can ensure your begonias grow strong and bloom beautifully all season long.
Success with begonias starts with patience and a basic understanding of what these plants need to thrive. The key to vibrant, healthy begonias is waiting for the perfect window when the air and soil are warm enough to support their tropical roots.
Understanding the Begonia Timeline
Knowing when to plant begonias outside is the most important step in your growing journey. Because begonias are tropical and semi-tropical plants, they have no natural defense against the cold. In their native habitats in South and Central America, Africa, and Asia, they never experience frost. This means they are very sensitive to even a light chill.
Most gardeners think only about the "last frost date," but for begonias, that is just the beginning. While the threat of frost must be gone, the actual temperature of the air and soil matters even more. Planting too early can cause the plant to stop growing or "sulk," which delays those beautiful flowers you are waiting for.
When we talk about the right time, we are looking for a specific weather pattern. You want to see a stretch of days where the environment feels like a warm spring or early summer afternoon. Waiting for this window is not a delay; it is an investment in the plant’s long-term health and flower production.
The Magic Number: 50 Degrees
The most reliable rule of thumb for begonias is the "50-degree rule." Before you move any begonia outside, nighttime temperatures should consistently stay above 50°F (10°C). Ideally, many varieties prefer the nights to be even warmer, closer to 60°F, but 50°F is the absolute minimum for safety.
If you plant while the nights are still dipping into the 40s, the plant may survive, but its growth will likely stall. Cold soil and chilly air can lead to a condition where the roots stop taking up nutrients efficiently. In some cases, the stress of the cold makes the plant more susceptible to rot if the soil is also damp.
To get the timing right, keep an eye on your local ten-day forecast. You are looking for a trend, not just a single warm night. Once you see that the lows are staying well above the 50-degree mark, you can feel confident that it is safe to start the transition process. If you want help matching planting time to your area, check Longfield Gardens’ hardiness zone map.
Key Takeaway: The 50-Degree Rule
- Wait for nighttime temperatures to stay consistently above 50°F.
- Avoid planting during a "warm spell" followed by a predicted cold snap.
- Warm soil is just as important as warm air for tropical root health.
Soil Temperature vs. Air Temperature
It is easy to check the air temperature with a phone or a window thermometer, but experienced gardeners know that soil temperature is the "quiet winner" in timing. Soil takes much longer to warm up than the air does. Even if the sun feels hot on your back, the ground six inches down might still be shivering from the winter.
Begonia tubers and roots need soil that is at least 60°F to really take off. If you put a warm-loving plant into cold, wet mud, the tuber can easily rot before it even has a chance to sprout. This is why begonias often do better in containers early in the season, as the soil in a pot warms up much faster than the soil in the ground.
If you are planting directly into your garden beds, you can help the soil warm up by removing any thick layers of mulch a week before you plan to plant. This allows the sun to hit the bare earth directly. Once the plants are established and the weather is hot, you can add the mulch back to help keep moisture in. For a deeper look at begonia light needs, see are begonias shade or sun plants?.
Starting Begonias Indoors to Cheat the Clock
Since begonias need such warm weather to go outside, many gardeners find that the growing season feels a bit short if they wait to start their tubers outdoors. To get a head start on those big, bold blooms, you can start your tubers indoors 8 to 12 weeks before the last frost date.
Starting indoors allows the plant to develop a strong root system and several sets of leaves while it is still too cold outside. By the time the weather is warm enough for outdoor planting, you aren't putting a dormant tuber into the ground; you are transplanting a vigorous, growing plant.
To start indoors, place your tubers in a shallow tray or small pots with a light, well-draining potting mix. The indented side of the tuber should face up—this is where the sprouts will come from. Only cover them with about a half-inch of soil. Keep them in a warm spot with indirect light. Once the "50-degree rule" applies to your outdoor weather, these "pre-started" plants will be ready to jump into action. For more indoor timing guidance, see when to plant begonia bulbs indoors.
The Importance of Hardening Off
Moving a begonia directly from a cozy, climate-controlled house to a breezy, sunny garden is a big shock. Even if the temperature is perfect, the intensity of the sun and the movement of the wind are new challenges for the plant. This is why we recommend a process called "hardening off."
Hardening off is simply a way of toughening up the plant’s leaves and stems so they can handle the outdoor world. This process usually takes about 7 to 10 days. Without it, you might notice the leaves turning white or "scorched" from the sun, or the brittle stems might snap in a light breeze.
How to harden off your begonias:
- Days 1-2: Place your plants outside in a fully shaded, protected spot for just 2 to 3 hours, then bring them back inside.
- Days 3-4: Increase the time to 5 or 6 hours. Let them experience a tiny bit of dappled morning light, but keep them out of the harsh afternoon sun.
- Days 5-6: Leave them out all day in their permanent shaded or semi-shaded location. Bring them in only at night.
- Days 7-10: If the nighttime temperatures are staying above 50°F, you can leave them out overnight in a protected spot. After this, they are ready to be planted in their final home.
Regional Timing Across the United States
Depending on where you live, your "when" will look very different. The United States has a wide range of climates, and begonias will react to each one differently. At Longfield Gardens, we ship our bulbs and tubers based on your specific USDA hardiness zone to help you get the timing right, but local weather always has the final say. You can check Longfield Gardens’ shipping information for more on zone-based timing.
The Southern States and Florida
In warmer regions like USDA zones 9 through 11, you can often plant begonias outside as early as March or April. In these areas, the challenge isn't the cold; it's the heat. Because it warms up so fast, you want to get your begonias established before the extreme humidity and heat of mid-summer arrive. In the deep South, begonias almost always need total shade during the afternoon to prevent the leaves from wilting.
The Mid-Atlantic and Midwest
For gardeners in zones 6 and 7, late May or early June is usually the sweet spot. Memorial Day is a common target date for many home gardeners in these regions. This ensures the "June Gloom" or late spring frosts have passed and the soil has had enough time to lose its winter chill.
The Northern States and Pacific Northwest
In zones 3 through 5, the window is much shorter. You might not be able to safely plant outside until mid-June. In these cooler climates, starting your begonias indoors is highly recommended. Because your summers are milder, your begonias may actually tolerate more sun than they would in the South, but they will still need protection from those chilly northern nights that can linger late into the season.
Choosing the Right Spot for the Right Time
"Right plant, right place" is one of our favorite rules. Even if you get the timing perfect, the location will determine how well your begonias perform. Most begonias are famous for loving the shade, but "shade" can mean different things depending on your yard. For more guidance, see where to plant begonias.
Begonias generally thrive in "dappled shade" or "filtered light." This is the kind of light you find under a tall tree where the sun peeks through the leaves but never hits the ground with full force. A porch that faces north or east is also an excellent spot.
If you plant in a spot that is too dark, the plants will become "leggy," meaning they grow long, thin stems as they reach for the light. If the spot is too sunny, the leaves may turn brown and crispy at the edges. When you move your plants outside, watch them closely for the first week. If they look happy and the leaves stay a rich green, you’ve found the perfect home for them.
Drainage: The Secret to Healthy Roots
Whenever you plant begonias, whether in the ground or in a pot, drainage is essential. "Drainage" is simply a way of saying how fast water leaves the soil. Begonias love moisture, but they hate sitting in water. If the soil stays like a wet sponge for too long, the tubers can develop rot.
If you are planting in the garden, look for a spot where water doesn't puddle after a rainstorm. You can improve heavy clay soil by mixing in some compost or finely ground bark. This creates tiny air pockets that help water move through and allow the roots to breathe.
For containers, always ensure there are holes in the bottom of the pot. We recommend using a high-quality potting mix rather than garden soil for containers. Potting mix is designed to stay fluffy and provide the perfect balance of moisture and air. If you are choosing containers, our begonia care guide has helpful tips for getting started.
What to Do Next: Preparing the Site
- Identify a spot with dappled shade or morning sun.
- Test the drainage by pouring water on the spot; it should soak in quickly.
- Clean up any debris or old mulch to let the sun warm the soil.
- Have your pots and fresh potting mix ready for transplanting.
Planting Depth and Spacing
Once the weather is right and your site is ready, getting the depth and spacing correct is a quiet win for your garden. If you plant too deep, the sprouts might struggle to reach the surface. If you plant too shallow, the heavy flowers might cause the plant to tip over.
For tuberous begonias, plant them about 1 inch deep. If you are transplanting a begonia that you started indoors or bought at a nursery, plant it at the same level it was growing in its pot. Avoid burying the stem deeper than it was before, as this can lead to stem rot. If you want more detail, see how deep to plant begonias.
Spacing depends on the variety:
- Upright Begonias: Space these about 8 to 12 inches apart. They grow vertically and need room for air to circulate between the plants.
- Trailing/Pendula Begonias: These are often best in hanging baskets. In a 12-inch basket, you can usually plant 2 or 3 tubers for a full, lush look.
- Wax Begonias: These are smaller and can be spaced 6 to 8 inches apart to create a dense carpet of color.
Watering and Fertilizing After Planting
After you move your begonias outside, they will need a little extra attention while they settle into their new home. Watering correctly—not constantly—is the goal. Immediately after planting, give them a good soak to settle the soil around the roots.
After that first watering, let the top inch of soil dry out before you water again. A simple way to check is to stick your finger into the soil. If it feels dry, it's time to water. If it feels damp, wait a day. This "deep, then dry" method encourages the roots to grow deeper into the ground, making the plant more resilient.
Begonias are heavy feeders, meaning they need plenty of nutrients to keep producing those large flowers. Once you see new growth appearing, you can start using a balanced, water-soluble fertilizer every two weeks. Follow the instructions on the label to avoid over-fertilizing, which can sometimes lead to more leaves but fewer flowers.
Identifying Different Begonia Types
Not all begonias have the exact same needs, so knowing what type you have can help you fine-tune your timing and care. For a broader overview, Longfield Gardens’ begonia collection is a good place to start.
Tuberous Begonias
These are the superstars of the shade garden. They produce massive, rose-like blooms in shades of red, pink, yellow, and orange. They grow from a thick, potato-like tuber. These are the most sensitive to cold and should be the last ones you move outside.
Wax Begonias (Semperflorens)
These are tough, versatile little plants often used for bedding. They have waxy leaves (hence the name) and can actually handle a bit more sun than tuberous varieties. Because they are often sold in cell packs at nurseries, they are already growing and can be planted as soon as the frost risk is gone.
Rex and Foliage Begonias
These are grown primarily for their incredible leaves, which can feature swirls of silver, purple, and deep green. While they can go outside in the summer, many people keep them as houseplants year-round. If you move them outside, keep them in full shade, as their delicate leaves burn very easily.
Cane Begonias (Angel Wing)
These grow on tall, bamboo-like stems and often have beautiful spotted leaves. They are quite sturdy but still need the "50-degree rule" to stay happy. They make excellent "thriller" plants in large patio containers.
Keeping Your Begonias Happy All Summer
Once your begonias are established, they are relatively low-maintenance. One of the best things about modern begonia varieties is that many are "self-cleaning." This means the old flowers fall off on their own, so you don't have to spend your time "deadheading" (pinning off dead blooms) to keep the plant looking neat.
However, if you notice the plant getting a bit too tall or "leggy," don't be afraid to pinch back the tips of the stems. This encourages the plant to grow outward rather than just upward, resulting in a bushier, fuller plant with more flower sites.
Keep an eye out for common garden visitors like slugs or snails, who occasionally enjoy a snack on begonia leaves. Placing your pots on a stand or using a bit of organic slug bait can easily manage this. Mostly, your job is to enjoy the show!
When to Bring Begonias Back Inside
As the summer winds down, you'll need to think about the "when" of bringing them back in. Just as begonias hate the cold of spring, they cannot handle the frost of autumn. When temperatures start to dip back toward 50°F in the fall, it is time to make a plan.
For tuberous begonias, many gardeners choose to "lift" the tubers and store them for the winter. This is a great way to save money and enjoy the same plants year after year. Once the foliage starts to turn yellow in the fall, cut the stems back to about an inch and carefully dig up the tuber. Let it dry in a cool, dark place for a few days, then store it in a paper bag filled with peat moss or sawdust.
If you have begonias in pots, you can simply bring the whole pot inside and keep it as a houseplant for the winter. They may not bloom as much indoors during the winter, but they will stay alive and be ready to go back outside as soon as the warm weather returns next spring.
Realistic Expectations for Your Garden
Gardening is a partnership with nature, and nature doesn't always follow a perfect schedule. Some years, spring arrives early, and you can get your begonias out by the beginning of May. Other years, a "late spring" might keep your plants indoors until June.
Soil quality, the amount of wind your yard gets, and even the color of your house (which can reflect heat) all play a role in how your begonias grow. If your plants don't look perfect the first week they are outside, don't worry. They often need a little time to adjust to their new environment. With consistent water and warm weather, they will usually find their stride and start blooming beautifully.
Conclusion
Planting begonias outside is all about timing and patience. By waiting for those consistent 50-degree nights and taking the time to harden off your plants, you set the stage for a spectacular summer display. Remember that these tropical treasures thrive in the shade, appreciate well-draining soil, and love a little bit of regular fertilizer to keep their blooms coming.
At Longfield Gardens, we are here to help you every step of the way, from choosing the perfect varieties to providing the support you need for a successful growing season. Gardening should be a rewarding, joyful experience, and there is no better way to celebrate summer than with a garden full of vibrant begonias.
- Wait for the warmth: 50°F nights are the minimum requirement.
- Prepare your plants: Use the 7-to-10-day hardening off process.
- Pick the right spot: Dappled shade and good drainage are key.
- Stay consistent: Water when the top inch of soil is dry.
"The secret to beautiful begonias isn't a magic green thumb—it's simply giving these tropical plants the warmth and shade they crave."
We hope this guide gives you the confidence to get your begonias outside at the perfect time. If you have questions about your specific order or need more advice, our team is always ready to help you grow a more beautiful garden.
FAQ
Can begonias survive a light frost if I cover them?
While covering plants can help some perennials, begonias are extremely tender and can be damaged by cold even without a direct frost hit. It is much safer to bring them indoors or wait until all danger of frost has passed and temperatures are consistently warm. If a surprise cold snap happens, bringing pots inside is always better than just covering them.
Why are the leaves on my begonias turning yellow after I moved them outside?
Yellow leaves often indicate that the plant is getting too much water or that the soil isn't draining well. Begonias prefer to have their soil stay moist but not soggy. Check the drainage holes in your pots and make sure you are letting the top inch of soil dry out before watering again. Occasionally, yellowing can also be a sign of "transplant shock" as the plant adjusts to new light levels.
How much sun can a begonia actually handle?
Most begonias prefer partial shade or filtered light, especially during the hottest part of the day. However, some varieties, like wax begonias with bronze-colored leaves, are bred to handle more sun than the green-leaved types. In northern climates, begonias can often tolerate more direct morning sun than they can in the high heat of the South. For more light guidance, see begonias in sun or shade.
Do I need to dig up my begonias every year?
In USDA zones 9-11, begonias can often stay in the ground year-round. However, in most of the United States (zones 3-8), begonias will not survive the winter outdoors. You can treat them as annuals and plant new ones each year, or you can dig up the tubers in the fall and store them in a cool, dry place to replant the following spring. If you’re unsure about your climate, revisit the hardiness zone map.
