Table of Contents
- Introduction
- Identifying Your Begonia Tuber
- Why Orientation Matters
- When to Start Your Begonias
- Step-by-Step Planting Guide
- Handling "Difficult" Tubers
- Light and Water Requirements
- Exploring Different Varieties
- What to Expect as They Grow
- Long-Term Care and Success
- Conclusion
- FAQ
Introduction
There is a unique sense of excitement that comes with planting your first begonia tubers. These small, unassuming brown disks hold the potential for some of the most spectacular, rose-like blooms you can grow in a shady garden. Whether you are looking to brighten up a covered porch with hanging baskets or add a splash of color to a quiet corner of your yard, tuberous begonias are a rewarding choice for gardeners of any skill level.
Getting started with these plants is a simple process, but it begins with one very specific question: which way is up? Because begonia tubers have a distinct shape, placing them in the soil correctly ensures the young sprouts can find the light quickly and develop strong, healthy stems. At Longfield Gardens, we want to help you feel confident from the moment your bulbs arrive at your door. If you're ready to shop, start with our Begonia Flower Bulbs for Sale collection.
This guide will walk you through the easy steps of identifying the top of a begonia tuber, how to plant them for the best results, and what to expect as they begin to grow. By getting this one detail right, you set the stage for a summer filled with lush foliage and vibrant, oversized flowers.
Identifying Your Begonia Tuber
Before you reach for your trowel, it helps to take a close look at the tuber itself. Begonia tubers are often compared to small potatoes because they are thick, fleshy, and store the energy the plant needs to grow. However, unlike a smooth potato, a begonia tuber is usually brown, somewhat hairy, and has a very specific "bowl" shape.
When you hold a tuber in your hand, you will notice that one side typically curves inward, while the other side is rounded and smooth. Understanding these two sides is the secret to successful planting. For a closer look at the shape and orientation, see How to Plant Tuberous Begonias: Which End Is Up?.
The Concave Side (The Top)
The side of the tuber that dips inward—much like a shallow bowl or a saucer—is the top. In gardening terms, this is called the "concave" side. This hollowed-out area is where the growing points, or "eyes," are located. Just like the eyes on a potato, these small bumps will eventually wake up and send stems toward the sun.
The Convex Side (The Bottom)
The rounded, domed side is the bottom, also known as the "convex" side. This part of the tuber should rest against the soil. While roots will eventually grow from several parts of the tuber, the rounded side provides a stable base for the plant to anchor itself.
Finding the "Eyes"
If your tuber is already starting to wake up, you might see tiny, pinkish or white nubs inside the hollowed-out bowl. These are the sprouts. Seeing these "eyes" is a great sign of a healthy tuber and makes it very easy to tell which way is up. If you don't see them yet, don't worry; they are simply resting and will appear once they feel the warmth of the soil and a bit of moisture.
Key Takeaway: Always look for the "bowl." The side that could hold a small amount of water is the side that faces the sky.
Why Orientation Matters
You might wonder what happens if a tuber is accidentally planted upside down. While plants are remarkably resilient and will often try to find their way to the surface, planting them correctly makes their job much easier.
When the tuber is placed "hollow side up," the new stems have a direct, unobstructed path to the light. If the tuber is upside down, the sprouts must grow downward first, then wrap around the side of the tuber to reach the surface. This extra effort can delay the blooming season and use up the plant's stored energy, sometimes leading to a weaker plant. By placing the tuber in the right direction, you ensure the fastest possible growth and the earliest flowers.
When to Start Your Begonias
Timing is just as important as orientation. Tuberous begonias are tropical plants by nature, which means they love warmth and are very sensitive to frost. Because they take a little while to "wake up"—often 8 to 12 weeks to reach full bloom—many gardeners prefer to give them a head start indoors.
If you live in a cooler climate, you can start your tubers in small pots or trays about two months before the last expected frost in your area. This allows the plant to develop a strong root system and several sets of leaves while it is still too cold to be outside. By the time the weather warms up, you will have a sturdy plant ready to go into the garden. For a zone-by-zone reference, see the USDA Hardiness Zone Map.
For those in warmer regions, you can plant your tubers directly into the soil once the ground has warmed and all danger of frost has passed. At Longfield Gardens, we coordinate our shipping based on your USDA hardiness zone to ensure your tubers arrive at the ideal time for planting in your specific area. See our Shipping Information page for details.
Step-by-Step Planting Guide
Once you have identified the top of your tuber and the timing is right, the actual planting is a quick and easy process.
1. Choose Your Container or Location
Begonias are versatile. They thrive in pots, hanging baskets, and garden beds. The most important factor is the soil. They need a "well-draining" mix, which simply means the water should move through the soil easily rather than sitting in a puddle. If you are planting in containers, use a high-quality potting soil.
2. Prepare the Soil
Loosen the soil in your pot or garden bed. If the soil is very dry, give it a light misting of water so it is damp but not soaking wet.
3. Set the Tuber
Place the tuber on the soil with the hollow "bowl" side facing up. If you are planting multiple tubers in a large container or garden bed, space them about 8 to 12 inches apart to give each plant room to breathe.
4. The Correct Depth
Begonia tubers do not need to be buried deep in the earth. In fact, they prefer to be quite shallow. Place the tuber so the top rim of the "bowl" is just barely covered by about half an inch to an inch of soil. Some gardeners even leave the very top of the tuber exposed until the first sprouts appear, then add a light dusting of soil later. For a deeper walkthrough, see How Deep Should You Plant Begonia Tubers?.
5. Water Lightly
After planting, give the tuber a small drink of water to help settle the soil around it. Be careful not to overwater at this stage. Since the tuber doesn't have roots yet, it cannot drink much water. Keeping the soil "moist like a wrung-out sponge" is the perfect balance.
What to Do Next:
- Check your local frost dates to plan your planting start.
- Gather your pots and a fresh bag of well-draining potting soil.
- Inspect your tubers for the hollow "bowl" side and any pink "eyes."
- Plant shallowly, covering the top with only an inch of soil.
Handling "Difficult" Tubers
Occasionally, you may come across a tuber that doesn't have a clear bowl shape. It might be round on both sides or look like a flat disk. If you find yourself holding a tuber and you truly cannot tell which side is up, don't let it stress you out.
The best approach for a "mystery" tuber is to plant it on its side. When a tuber is on its side, the sprouts can easily grow from the top edge and the roots can emerge from the bottom edge. This is a safe "middle ground" that allows the plant to correct its own orientation as it grows.
Another trick is to wait. You can place the tubers on a tray of damp peat moss in a warm room without burying them. Within a week or two, the tiny pink "eyes" will usually begin to swell. Once you see those sprouts, you will know exactly which way to plant them.
Light and Water Requirements
Begonias are famous for being the "stars of the shade," but they still need a specific type of light to perform their best. They generally prefer "filtered" or "dappled" light—the kind of light that peeks through the leaves of a tall tree.
While they can handle a bit of gentle morning sun, the hot, direct midday sun can be too much for their tender leaves and petals. If you notice the edges of the leaves turning brown or looking "crispy," your begonias might be getting a bit too much sun. Moving a pot just a few feet into more shade can often fix the problem.
Watering Correctly
Watering is the most important part of begonia care. Because the stems and tubers are fleshy and hold a lot of moisture, they are prone to "rot" if they stay too wet. Rot is simply when a plant begins to break down because it has been sitting in soggy soil for too long. For more watering guidance, see Do You Water Begonia Tubers After Planting?.
The rule for begonias is "deeply but infrequently." Wait until the top inch of soil feels dry to the touch before you water again. When you do water, try to pour the water directly onto the soil rather than over the leaves or into the center of the tuber's "bowl." Water sitting in the hollow part of the tuber can lead to issues, so aim for the surrounding soil instead.
Exploring Different Varieties
One of the reasons we love begonias at Longfield Gardens is the incredible variety of flower shapes and growth habits available. If you like the upright, rose-like look, the Upright Double Begonias collection is a great place to start.
- Upright Begonias: These grow in a mounded shape and are perfect for garden borders or the center of a patio pot. Varieties like Roseform produce massive, multi-petaled flowers that look like prize-winning roses.
- Hanging Basket (Pendula) Begonias: These varieties have stems that naturally drape downward. They are specifically bred to cascade over the sides of hanging baskets or window boxes, creating a waterfall of color.
- Fimbriata Begonias: These have unique, "fringed" edges on their petals, giving them a frilly, textured appearance that stands out in a container display. For a full overview of begonia types, see Types of Begonias.
- Non-Stop Begonias: As the name suggests, these are bred to produce an abundance of flowers all season long. They are usually more compact, making them ideal for smaller pots and front-of-the-border planting. Browse Non Stop Begonias for the collection.
Regardless of the variety you choose, the planting method remains the same: hollow side up, shallow depth, and plenty of filtered light.
What to Expect as They Grow
Gardening requires a little patience, and begonias are no exception. After you plant your tubers, you might not see anything happening for a few weeks. This is normal! The tuber is busy growing roots under the soil before it sends up its first leaves.
Once the sprouts break the surface, growth will speed up. You will first see small, heart-shaped leaves that often have a beautiful, reddish tint or interesting patterns. Soon after the foliage fills out, the first flower buds will appear.
For the largest flowers, some gardeners choose to remove the smaller "female" buds (which usually appear in pairs next to a larger "male" bud), but this isn't necessary for a beautiful display. Most home gardeners find that letting the plant do its own thing results in a lush, full look with plenty of blooms to enjoy.
Long-Term Care and Success
To keep your begonias looking their best throughout the summer, a little bit of maintenance goes a long way.
Fertilizing
Because begonias produce so many flowers, they are "heavy feeders." This means they use up the nutrients in the soil quite quickly. Using a balanced, water-soluble fertilizer every two weeks will help the plant continue to produce new buds and healthy green leaves. Always follow the instructions on the fertilizer label for the best results. For more season-long care tips, see Tips for Growing Tuberous Begonias.
Deadheading
"Deadheading" is a gardening term that simply means removing flowers that have finished blooming and are starting to wilt. For begonias, this is very easy. When a flower looks spent, you can gently snap it off at the base of its small stem. This keeps the plant looking tidy and encourages it to put its energy into creating new flowers rather than seeds.
Troubleshooting Made Simple
If your begonia isn't blooming as much as you'd like, check the light. Often, a plant in too much shade will have beautiful leaves but very few flowers. Moving it to a spot with just a little more indirect light can provide the "spark" it needs to start blooming. If the plant looks yellow or the stems feel soft, it is likely getting too much water. Simply let the soil dry out for a few days and adjust your watering schedule.
"The secret to begonia success isn't complicated: find the hollow side, don't bury it too deep, and let the soil dry out slightly between waterings. These three small steps lead to a stunning summer display."
Conclusion
Planting begonia tubers is one of the easiest ways to bring high-impact color to the shaded areas of your home. By simply remembering to plant the tuber with the hollow, bowl-like side facing up and keeping it at a shallow depth, you’ve already done the most important work. These plants are generous bloomers that will reward your minimal effort with a constant parade of flowers from mid-summer right through the first frost.
Whether you are tucking them into a garden bed or letting them cascade from a basket, tuberous begonias offer a classic beauty that never goes out of style. We invite you to explore the many colors and shapes available at Longfield Gardens and start your own shade-garden tradition this season. Learn more in our All About Begonias guide.
- Check the shape: Hollow side always faces up.
- Don't overbury: Keep the tuber only about an inch below the soil.
- Start early: Give them 8 weeks indoors if you live in a cold climate.
- Water wisely: Let the soil dry a bit before adding more water.
Ready to start your garden? Visit our shop to find your favorite begonia varieties and have them delivered right to your door.
FAQ
What happens if I plant my begonia tuber upside down?
If planted upside down, the tuber will still attempt to grow, but the sprouts will have to travel around the tuber to reach the surface. This can result in delayed blooming, stunted growth, or a weaker plant overall. If you realize you've planted one incorrectly, you can gently dig it up and flip it over as long as the sprouts haven't grown too long. If you have any concerns after ordering, our 100% Quality Guarantee is there to help.
How deep should I plant begonia tubers in a pot?
Begonia tubers should be planted very shallowly. The top of the tuber (the hollow side) should be covered by no more than half an inch to one inch of potting soil. If you bury them too deep, the sprouts may struggle to reach the surface, and the tuber is more likely to rot in the damp, deep soil.
Do begonia tubers need to be started indoors?
While it isn't strictly necessary, starting begonia tubers indoors 8 to 12 weeks before the last frost is highly recommended. Because they have a long growing season and take a while to begin flowering, starting them early ensures you get the maximum amount of bloom time during the summer months.
My begonia tuber is flat on both sides. Which way is up?
If your tuber lacks a clear concave "bowl" shape, look for any small pink or white nubs, which are the growth eyes. If those aren't visible, the safest method is to plant the tuber on its side. This allows the plant to naturally direct its stems upward and its roots downward without the risk of being completely upside down.