Introduction
Tuberous begonias are among the most rewarding flowers you can grow in a shady yard, and our Begonia Flower Bulbs for Sale collection makes it easy to find the right tubers. They offer large, rose-like blooms and lush foliage in areas where many other flowering plants struggle to find enough light. At Longfield Gardens, we enjoy seeing how these tropical beauties can transform a dim patio or a north-facing garden bed into a vibrant display of color.
This guide is designed for home gardeners who want to get the basics right from day one. Whether you are planting in a decorative container or directly into your landscape, the success of your season depends largely on a few simple steps. We will focus on the most common question: exactly how deep should you plant your begonia tubers for the best results? For a broader overview of types and care, see our All About Begonias guide.
By understanding the proper planting depth and orientation, you can ensure your begonias develop strong root systems and healthy stems. Getting this right early on leads to a summer filled with continuous, spectacular blooms.
The Short Answer: Begonia Planting Depth
When you are ready to plant your begonia tubers, the most important rule is to keep them near the surface. For most tuberous varieties, you should plant the tuber so it is covered by about one inch of soil. If you are planting in a very protected container, you can even leave the very top of the tuber slightly exposed or just barely dusted with soil.
Planting at this depth provides the perfect balance for the plant. It is deep enough to keep the tuber moist and stable as the stems grow taller. At the same time, it is shallow enough that the delicate new sprouts do not have to struggle to reach the light. If a tuber is buried too deep, it may struggle to sprout, or the excess moisture in the soil could cause the tuber to rot before it ever gets started.
Key Takeaway: For both garden beds and containers, aim to have about one inch of soil sitting on top of the begonia tuber.
Determining Which Side Faces Up
Before you worry about the depth of the hole, you must identify which side of the tuber is the top. Begonia tubers have a unique shape that makes this relatively simple once you know what to look for.
One side of the tuber is usually rounded or smooth. The other side has a distinct indentation or a "hollow" look, similar to a shallow bowl. The side with the indentation is the top. This is where the leaf and flower sprouts will emerge. Always plant the tuber with this hollow side facing upward.
If you happen to see small, pinkish "eyes" or buds already starting to grow in that hollow area, you are in luck. Those are the future stems. If your tuber is perfectly smooth and you are having trouble telling the sides apart, look for the remains of old roots on the rounded side. When in doubt, you can also plant the tuber on its side; the plant will naturally direct its sprouts toward the light and its roots toward the soil.
Planting Begonias in Containers
Begonias are exceptional candidates for pots, window boxes, and hanging baskets. For more container planning tips, see Can Begonias Be Planted in Pots? Container Garden Guide. Because we can control the soil and drainage in a container, these plants often perform even better in pots than they do in the ground. A cascading variety like Begonia Hanging Golden Balcony is especially useful when you want color that spills over the edge.
Choosing the Right Pot
A 6-inch pot is usually perfect for one large begonia tuber. If you are using a larger planter, you can group several tubers together. We recommend using high-quality, well-draining potting soil rather than heavy garden soil. This ensures that the water can move through the pot easily, which keeps the tuber healthy.
Step-by-Step Container Planting
- Fill your container with potting mix until it is about two inches from the rim.
- Create a shallow nest in the center of the soil.
- Place the tuber in the nest with the hollow side facing up.
- Cover the tuber with one inch of soil.
- Lightly press the soil down to ensure it is making contact with the tuber, but do not pack it tightly.
If you are planting trailing begonias in a hanging basket, Begonia Hanging Pink Balcony is a lovely choice. The only difference is that you may want to space the tubers slightly closer to the edges of the basket so the flowers can cascade over the sides as they grow.
Planting Begonias in the Garden
In the landscape, begonias work best in borders or under the shade of high-branching trees. Before you plant, it is helpful to loosen the soil in the area to a depth of about six inches. This makes it easier for the fine, fibrous roots of the begonia to spread out.
Site Preparation
Begonias need "the right place," which means a spot with excellent drainage. If your garden soil stays soggy for hours after a rain, the tubers may not thrive. You can improve drainage by mixing in some compost or leaf mulch. This also adds nutrients that help the plant produce more flowers.
Depth and Spacing in the Ground
Just like in containers, the depth in the garden should be about one inch. Dig a shallow hole, set the tuber in with the "bowl" side up, and cover it. For spacing, we suggest leaving 8 to 12 inches between each plant. This allows for plenty of air circulation, which helps keep the foliage dry and healthy throughout the humid summer months. For more spacing guidance, see How Far Apart Do You Plant Begonias? Tips for Lush Growth.
What to do next:
- Check your soil drainage by pouring a bucket of water on the spot.
- Loosen the soil with a hand trowel.
- Mark your spacing with small stakes or stones before digging.
- Dig each hole 1 inch deep and set the tubers in place.
Why Timing Matters More Than Depth
While planting depth is a "quiet winner" for garden success, timing is just as critical. Begonias are tropical plants. They have no tolerance for frost and will not grow if the soil is cold and damp.
We recommend waiting to plant your begonias outdoors until the soil temperature reaches about 60°F. In most regions, this is well after the last spring frost date. If you plant them too early in cold, wet soil, the tuber will simply sit there, increasing the risk of rot. Patience is worthwhile here; once the weather warms up, begonias grow very quickly. For more outdoor-planting guidance, see Can I Plant Begonia Outside? Expert Tips for Outdoor Growth.
If you live in a northern climate with a short growing season, you can start your tubers indoors 8 to 12 weeks before the last frost. This gives the plants a head start so they are already blooming by the time you move them to your patio.
Starting Tubers Indoors for Early Blooms
Starting begonias indoors is a great way to enjoy a longer season of color. For a step-by-step walkthrough, see How to Start Tuberous Begonias Indoors. The process is very similar to outdoor planting, but you have more control over the environment.
You can use individual small pots or a shallow tray filled with a few inches of moist potting mix. Place the tubers about an inch apart in the tray. At this stage, you don't even need to cover them completely with soil; you can leave the tops exposed so you can watch for the first signs of growth.
Once you see green sprouts that are about an inch tall, you can cover them with a little more soil or transplant them into their final pots. Keep the tray in a warm room (around 70°F) with bright, indirect light. A windowsill that doesn't get harsh, direct afternoon sun is usually a perfect spot.
Watering Correctly After Planting
Watering is the area where many gardeners make the mistake of doing "too much." When you first plant a begonia tuber—whether indoors or out—it does not have any roots or leaves yet. This means it cannot "drink" much water.
After the initial planting, give the soil a light watering to settle it around the tuber. After that, wait. Do not water again until you see the first green sprouts emerging from the soil. Keeping the soil too wet before the plant has a root system is a common cause of failure. For more care tips, see Tips for Growing Tuberous Begonias.
Once the plant is established and has several leaves, you can begin a more regular watering schedule. The simple rule is to water deeply, then let the surface of the soil dry out a bit before watering again. For begonias in pots, you may need to water more frequently during the heat of the summer, especially if they are in porous clay pots.
Choosing High-Quality Tubers
The size and quality of the tuber you start with will dictate the size of the plant you get. Larger tubers have more stored energy, which results in more stems and a higher volume of flowers. At Longfield Gardens, we provide premium 5/6 cm tubers because they consistently produce the most impressive displays for home gardeners. If you want a fuller display, Begonia Upright Double Superba Mix - Bulk Offer is a strong choice.
When you receive your tubers, they should feel firm and heavy for their size, similar to a fresh potato. If you aren't ready to plant them immediately, keep them in a cool, dry, and dark place. If you're planning an order, review our Shipping Information page. This keeps them dormant until the weather is right for planting.
The Role of Soil and Fertilizer
Begonias are "heavy feeders," meaning they need plenty of nutrients to keep those large blooms coming all summer long. While the planting depth gets the roots started, the soil quality keeps the plant going.
If you are planting in the ground, mixing in compost provides a slow-release source of food. For container plants, we recommend using a balanced, water-soluble fertilizer every two weeks once the plant is actively growing. This ensures the plant doesn't run out of energy mid-season. Always follow the instructions on the fertilizer label to ensure you are providing the right amount.
Handling Common Planting Challenges
If your begonias aren't sprouting after a few weeks, don't worry. These plants can sometimes be slow to wake up from dormancy. Before you change anything, check the temperature. If the room or the soil is below 60°F, the tuber is likely just waiting for more warmth.
If the soil feels very wet, you might have overwatered. In this case, the best move is to stop watering entirely and let the soil dry out. Remember our rule of "one change at a time." If you move the plant to a warmer spot, wait a week to see if that triggers growth before trying another fix.
Key Takeaway: Warmth is the most common trigger for begonia growth. If sprouts are slow to appear, a warmer location is often the only "fix" needed.
Upright vs. Trailing Begonias
When deciding how deep to plant, it helps to know which type of begonia you have. Upright Double Begonias grow on sturdy stems and are best for garden beds or the center of large pots.
- Upright Begonias: These grow on sturdy stems and are best for garden beds or the center of large pots.
- Trailing Begonias: These have more flexible stems that naturally drape downward. These are the best choice for hanging baskets.
The planting depth for both is the same (one inch), but their placement in a container differs. Plant upright varieties in the center of the pot. For trailing types, you can plant them at a slight angle toward the edge of the pot to encourage that beautiful cascading habit.
Realistic Expectations for Your Begonias
While we provide high-quality tubers and the best advice possible, nature always has the final say. Your begonias will grow at different rates depending on your local humidity, the amount of shade they receive, and the daily temperature.
In very hot climates, begonias may need almost total shade to keep their leaves from scorching. In cooler, northern climates, they can handle a bit more morning sun. You might notice that your plants produce both "single" and "double" flowers on the same plant. This is perfectly normal! Tuberous begonias produce male and female flowers; the male flowers are the large, showy doubles, while the female flowers are smaller and usually single. If you want to explore a classic double-flowered option, Begonia Upright Double Superba White is a good example.
Transitioning Begonias Outdoors
If you started your begonias indoors, you cannot move them directly into the full outdoor environment all at once. They need a "hardening off" period. This is a simple process of getting the plants used to the wind, temperature swings, and brighter light of the outdoors. If you are not sure how your local climate affects timing, check the Hardiness Zone Map.
Start by placing your pots in a sheltered, shady spot outside for a few hours during the day, then bring them back inside at night. Over the course of a week, gradually increase the time they spend outside. Once the nighttime temperatures are consistently above 60°F, they can stay outside for the rest of the season. This transition ensures the stems stay strong and the leaves don't get stressed by the change in environment.
Summary of Begonia Planting Steps
To ensure your begonias get the best start possible, keep these simple steps in mind:
- Check the Tuber: Identify the hollow side (top) and the rounded side (bottom).
- Measure the Depth: Plant the tuber about one inch deep in well-draining soil.
- Watch the Temperature: Only move plants outdoors when the soil and air are warm (60°F+).
- Water Sparingly: Wait for the first sprouts to appear before you start a regular watering routine.
- Give Them Space: Leave 8–12 inches between plants in the garden to allow for air movement.
Conclusion
Planting begonias is an easy and enjoyable way to bring life to the quiet, shady corners of your yard. By focusing on a few basics—like the one-inch planting depth and the "bowl-side up" orientation—you set the stage for a successful growing season. Whether you are a beginner or an experienced gardener, these simple rules help ensure your garden remains a source of beauty rather than stress.
At Longfield Gardens, we are committed to helping you find success with every tuber you plant, and we stand behind that promise with our 100% Quality Guarantee. From choosing the right variety to getting the planting depth just right, every small step leads toward that rewarding moment when the first big bloom opens.
Begonias prove that you don't need a sun-drenched yard to have a spectacular flower garden. With just a little warmth, the right soil depth, and a bit of patience, these tubers will reward you with color from early summer right through the first frost.
Your next step is to choose a beautiful spot in your garden and get those tubers into the ground or a favorite pot. Enjoy the process and the beautiful results that follow.
FAQ
Can I plant begonias in full sun?
Most tuberous begonias prefer partial to full shade. In northern climates, they can handle some morning sun, but in hotter southern regions, they need protection from the intense afternoon heat to prevent the leaves and flowers from wilting or burning.
What happens if I plant my begonia tuber upside down?
If a tuber is planted upside down, it will eventually try to send its sprouts around the side of the tuber to reach the surface. This uses up a lot of the plant's energy and results in a much later start to the blooming season. If you realize you've planted one upside down early on, you can gently dig it up and flip it over.
Should I add mulch over my begonias?
While mulch is great for many plants, we recommend being careful with begonias. Heavy mulch can trap too much moisture against the stems, which may lead to rot. If you do use mulch, keep it an inch or two away from the base of the begonia stems.
Do I need to dig up my begonia tubers in the fall?
In most parts of the United States (Zones 3-8), begonias will not survive the winter outdoors. If you want to keep them for next year, you should dig them up after the first light frost, let them dry, and store them in a cool, dark place until spring. If you are not sure about your zone, check the Hardiness Zone Map. This allows you to enjoy the same beautiful plants year after year.
