Table of Contents
- Introduction
- The Best Depth for Planting Begonia Tubers
- Which Way Is Up? Orientation Matters
- When to Put Your Begonias in the Ground
- Choosing the Right Spot for Success
- How to Plant Begonias in Containers
- Spacing and Depth in the Garden
- Watering Wisely After Planting
- Feeding Your Begonias for Maximum Blooms
- Simple Maintenance for a Tidy Garden
- Lifting and Storing Tubers for Next Year
- Creating Beautiful Combinations
- Conclusion
- FAQ
Introduction
Few things bring more joy to a shaded garden than the vibrant, jewel-toned colors of begonias. These plants are beloved for their ability to turn a quiet corner of the yard into a lush, tropical-looking retreat. Whether you are planting them in elegant patio pots or along a woodland border, begonias offer a long season of beauty with relatively little effort. At Longfield Gardens, we enjoy helping gardeners find the perfect varieties to brighten their outdoor spaces.
This guide is designed for any gardener who wants to master the basics of planting these stunning flowers. We will focus specifically on tuberous begonias, which grow from a bulb-like structure called a tuber. For a broader overview, see All About Begonias. Knowing how deep to plant begonias is one of the most important steps to ensure they sprout quickly and stay healthy throughout the summer. By following a few simple rules, you can enjoy a spectacular display of blooms from midsummer until the first frost of autumn.
The Best Depth for Planting Begonia Tubers
The short answer to the question of depth is quite simple. You should plant begonia tubers about 1 inch deep. This means there should be approximately one inch of soil covering the top of the tuber once it is tucked into its spot.
If you plant them too deep, the sprouts may struggle to reach the surface. If they are too shallow, the roots might not have enough stability to support the heavy, flower-laden stems as the plant matures. For a more detailed look, see How Deep to Plant Tuberous Begonia for Best Results. A depth of one inch provides the perfect balance of protection and access to the warmth of the sun.
When you are working in the garden, you do not need a ruler to be exact. Using your thumb as a guide is a great way to estimate. Simply press the tuber into the soil so the top is just below the surface, then sprinkle a light layer of soil over the top. This shallow planting method is especially helpful if you are starting your begonias indoors early in the spring.
Why Shallow Planting Works Best
Begonias are tropical plants that love warmth. The soil near the surface warms up much faster than the soil deep underground. By keeping the tuber near the top, you encourage the plant to "wake up" from its dormant state.
Shallow planting also helps prevent moisture from sitting on top of the tuber for too long. Tuberous begonias are sensitive to excess water. If they are buried deep in cold, damp soil, they can become sluggish or fail to sprout. Keeping them in that top inch of soil ensures they get the air and warmth they need to thrive.
Adjusting Depth for Sprouted Plants
Sometimes you might buy begonias that have already started growing in small nursery pots. In this case, the rules change slightly. You should dig a hole just deep enough so that the plant sits at the same level it was in its original container. Avoid burying the fleshy green stems, as this can lead to issues with the plant's health.
Key Takeaway: Plant begonia tubers 1 inch deep to ensure they stay warm and sprout quickly. If the plant already has green stems, keep the soil level consistent with its nursery pot.
Which Way Is Up? Orientation Matters
Before you worry about the exact depth, you must make sure the tuber is facing the right direction. This is a common question for many beginners because begonia tubers look a bit different than a typical tulip or daffodil bulb.
Most begonia tubers are shaped like a small, thick bowl or a saucer. One side will be rounded and smooth. The other side will have a slight hollow or indentation.
Identifying the Top
The indented or "hollow" side is the top. This is where the new stems and leaves will emerge. You may even see tiny pink or white buds, often called "eyes," starting to peek out from this hollow area. Always plant the tuber with this hollow side facing up toward the sky.
Identifying the Bottom
The rounded, smooth side is the bottom. This is where the roots will grow to anchor the plant and gather nutrients. If you accidentally plant a tuber upside down, it will try to grow, but the stems will have to curve around the tuber to reach the light. This wastes the plant's energy and delays your flowers.
- Look for the bowl: The "cup" side always goes up.
- Check for buds: Any small sprouts should point toward the surface.
- Feel the texture: The bottom is usually smoother and more rounded.
When to Put Your Begonias in the Ground
Timing is just as important as depth. Because begonias are tropical in origin, they have no tolerance for frost. Planting them too early in cold soil can stunt their growth.
We recommend waiting to move your begonias outside until the danger of frost has completely passed. A good rule of thumb is to wait until nighttime temperatures consistently stay above 50°F (10°C). If you're not sure about your local timing, check the Hardiness Zone Map. If the soil is still cold and clammy, the tubers will simply sit there and wait. It is much better to wait for a warm stretch of weather so the plants can hit the ground running.
Starting Indoors for an Early Show
If you live in a northern climate with a short growing season, you can start your begonias indoors. This gives them a head start so they are ready to bloom sooner once summer arrives. For step-by-step help, read How to Start Tuberous Begonias Indoors.
About 8 to 12 weeks before the last frost date, place your tubers in shallow trays filled with damp potting soil. Follow the same 1-inch depth rule. Keep the trays in a warm spot with indirect light. Once the weather warms up and the plants have a few sets of leaves, you can move them to their permanent summer home.
Hardening Off Your Plants
If you start your plants indoors, they need a little time to get used to the "real world" before they stay outside for good. This process is called hardening off. Start by putting them in a shaded, protected spot for a few hours a day. Gradually increase their time outside over the course of a week. This prevents the leaves from getting scorched by the sun or whipped by the wind.
Choosing the Right Spot for Success
Once you know how deep to plant, you need to decide where to put them. Begonias are famous for their love of shade, but they do need some light to produce those big, showy flowers.
The Perfect Light Balance
Most varieties prefer filtered light or "dappled" shade. A spot that gets soft morning sun and protection from the harsh afternoon heat is ideal. If you plant them in full, direct sun in a hot climate, the leaves may turn brown at the edges or look stressed. Conversely, if the spot is too dark, the stems may grow long and "leggy" as they reach for the light, and you will see fewer flowers.
Soil and Drainage Requirements
The quality of your soil makes a big difference in how your begonias perform. These plants love soil that is rich in organic matter but also very well-drained.
If your garden soil is heavy clay and stays wet for a long time after rain, the tubers may not be happy. You can improve drainage by mixing in some compost or peat moss. For containers, use a high-quality potting mix rather than garden soil. Potting mixes are designed to stay fluffy and let extra water drain away quickly.
What to do next:
- Check your local frost dates to time your planting correctly.
- Prepare your pots or garden beds with fresh, well-draining soil.
- Locate a spot with morning sun and afternoon shade.
- Find the hollow side of each tuber before you start digging.
How to Plant Begonias in Containers
Begonias are some of the best plants for containers, hanging baskets, and window boxes, and Hanging Begonias are especially useful for pots because the soil stays warmer and drainage is easier to control.
Selecting the Right Pot
Make sure your container has at least one drainage hole at the bottom. If water cannot escape, it will pool around the tuber and cause problems. For a single tuber, a pot that is 6 to 8 inches wide is usually sufficient. If you are planting a larger display, like a window box, you can space multiple tubers together. A trailing variety like Begonia Hanging Golden Balcony is a natural choice for this style.
Spacing in Containers
In a pot, you can space begonias a bit closer than you would in a garden bed. Aim for about 4 to 6 inches between tubers. This creates a dense, "spilling" look as the foliage grows. Remember to keep that 1-inch depth even in a container.
Step-by-Step Potting Guide
- Fill the pot: Use a light potting mix, leaving about 2 inches of space at the top.
- Place the tuber: Set the tuber in the center with the hollow side facing up.
- Cover: Add an inch of soil over the top.
- Water lightly: Give it a small drink to settle the soil, but do not soak it until you see green growth.
- Place in warmth: Put the pot in a warm area with indirect light to jump-start growth.
For a fuller display, try Begonia Non Stop Mix - Bulk Offer.
Spacing and Depth in the Garden
If you are planting begonias directly into your flower beds, they need a little more room to breathe. Proper spacing ensures good air circulation, which keeps the leaves dry and healthy.
Standard Garden Spacing
For most tuberous begonias, space the tubers 8 to 12 inches apart. This gives the plant plenty of room to reach its full width without crowding its neighbors. If you are planting a larger, coordinated display, Begonia Upright Double Superba Mix - Bulk Offer can fill the space with color. If you are planting wax begonias (the smaller bedding type), they can be spaced similarly to create a carpet of color.
Creating a Natural Look
To make your garden look more natural, avoid planting in straight, rigid lines. Instead, try planting in "drifts" or groups of three or five. This mimics how plants grow in nature and makes a bigger visual impact. As long as you maintain the 1-inch depth and the proper spacing, your begonias will quickly grow together to fill the space.
Watering Wisely After Planting
Watering is the area where most new begonia growers feel a little nervous. The key is to find the middle ground. You want the soil to be moist, like a wrung-out sponge, but never dripping wet.
Watering the Tuber
Immediately after planting, give the soil a light watering to settle it around the tuber. After that first drink, wait until you see green sprouts appearing before you start a regular watering routine. A dormant tuber does not have roots yet, so it cannot "drink" much water. Too much water at this stage can lead to the tuber staying too cold.
Established Plant Care
Once the plant is growing vigorously and has several leaves, you can water more frequently. Check the soil every few days by sticking your finger an inch into the dirt. If it feels dry, it is time to water.
In the heat of summer, containers and hanging baskets may need water every day. Always try to water the soil directly rather than splashing the leaves. Watering at the base of the plant helps keep the foliage dry, which prevents common garden issues like powdery mildew.
Feeding Your Begonias for Maximum Blooms
Begonias are "heavy feeders." This means they use a lot of energy to produce those massive, colorful flowers all summer long. For more care advice, see Tips for Growing Tuberous Begonias.
Choosing a Fertilizer
A balanced, water-soluble fertilizer is usually the easiest way to feed begonias. Look for a product where the numbers on the label (like 10-10-10 or 20-20-20) are roughly equal. You can also use a formula designed for flowering plants, which often has a slightly higher middle number to encourage more blooms.
Frequency of Feeding
Start fertilizing once the plant is well-established with several sets of leaves. Most gardeners find success by feeding their begonias every two to three weeks. Always follow the instructions on the fertilizer package to avoid over-feeding. If you notice the plant is growing plenty of leaves but no flowers, you might be using too much nitrogen. In that case, switch to a bloom-boosting formula.
Simple Maintenance for a Tidy Garden
Begonias are very low-maintenance, but a few minutes of "housekeeping" each week will keep them looking their best.
Deadheading Flowers
"Deadheading" simply means removing flowers that have started to fade or wilt. While many modern begonias are "self-cleaning" (the old flowers fall off on their own), picking off the spent blooms keeps the plant looking neat. It also encourages the plant to put its energy into making new flowers instead of trying to produce seeds.
Monitoring for Health
Keep an eye on the leaves. Healthy begonia leaves should be firm and vibrant. If you see yellowing leaves, it might be a sign that the soil is staying too wet. If the leaves look crispy or brown at the edges, the plant might need more shade or more frequent watering. Adjusting these small factors is usually all it takes to get the plant back on track.
Key Takeaway: Regular feeding and light deadheading are the "secret" to a summer-long explosion of begonia flowers.
Lifting and Storing Tubers for Next Year
One of the best things about tuberous begonias is that they can last for many years. Because they are not hardy in most parts of the US, you will need to bring them inside for the winter if you live in a cold climate.
When to Bring Them In
Wait until the first light frost in autumn. The cold will turn the foliage yellow or brown, which is a signal to the plant that it is time to go dormant. At this point, carefully dig up the tubers.
The Curing Process
Cut off the stems, leaving about an inch attached to the tuber. Gently shake off any excess soil. Place the tubers in a cool, dry spot (like a garage or basement) for a few days to let them dry out. This is called "curing."
Winter Storage
Once they are dry, place the tubers in a box filled with peat moss, perlite, or even shredded newspaper. Store the box in a cool, dark, and dry place where temperatures stay between 40°F and 50°F. In the spring, you can pull them out, follow the 1-inch planting depth rule again, and start the cycle all over. It is a very rewarding way to grow your garden collection over time.
Creating Beautiful Combinations
Because begonias thrive in the shade, they are perfect partners for other shade-loving plants. For more pairing ideas, see What Plants Look Good With Begonias? Top Companion Plants.
- With Foliage Plants: Pair the bright flowers of begonias with the interesting leaves of hostas, caladiums, or ferns. The contrast between the soft fern fronds and the waxy begonia petals is stunning.
- Trailing Pairs: In hanging baskets, mix trailing begonias with fuchsia or lobelia for a multi-layered look.
- Color Themes: Use all-white begonias to create a "moon garden" that glows in the evening light. Or, mix oranges and yellows for a high-energy tropical feel.
The possibilities are endless when you start with healthy, correctly planted tubers.
Conclusion
Planting begonias is an easy and rewarding way to add high-impact color to the shaded parts of your landscape. By remembering the simple rule of planting your tubers 1 inch deep with the hollow side facing up, you set your plants up for a successful growing season. These tropical beauties ask for very little—just some warm soil, consistent moisture, and a bit of protection from the midday sun.
Whether you are a seasoned gardener or just starting your first container, the lush foliage and dramatic blooms of begonias are sure to impress. We encourage you to try a few different varieties this year and see just how much life they can bring to your porch, patio, or garden beds.
- Plant at 1 inch depth: This is the sweet spot for warmth and stability.
- Orient correctly: Hollow side always faces the sky.
- Wait for warmth: Only move plants outside when nights are above 50°F.
- Provide drainage: Use pots with holes and loose, airy soil.
The next step is to choose your favorite colors and get your tubers ready for spring. If you love crisp white blooms, Begonia Upright Double Superba White is a beautiful place to start.
"Gardening is about the joy of the process, and begonias are the perfect partner for a stress-free, beautiful summer garden."
FAQ
What happens if I plant my begonia tubers deeper than one inch?
If tubers are planted too deep, they may take much longer to sprout because the soil is cooler further down. In some cases, the young stems might struggle to push through the extra weight of the soil, leading to a weaker plant. Stick to the one-inch rule for the fastest and healthiest growth.
Can I plant begonias in full sun?
Most tuberous begonias prefer partial shade or filtered light, especially in hot climates. While some specific varieties are bred to be sun-tolerant, the delicate petals and leaves of most begonias can scorch in intense afternoon sun. If you have a sunny spot, look for "sun-tolerant" labels or ensure the plants get plenty of extra water.
Do I need to soak begonia tubers before planting?
You do not need to soak them, though some gardeners like to place them on a damp paper towel for 24 hours to "wake them up." Most of the time, simply planting them in moist potting soil is enough to trigger growth. If the tubers feel very dry and shriveled, a very brief soak (under 30 minutes) in room-temperature water can help, but it is rarely necessary.
How many begonia tubers should I put in a 12-inch hanging basket?
For a 12-inch basket, three tubers are usually perfect. This allows enough space for each plant to grow its roots while ensuring the basket looks full and overflowing by midsummer. Remember to space them evenly and keep them just an inch below the soil surface.