Introduction
Imagine transforming a quiet, shaded corner of your yard into a vibrant gallery of color. Tuberous begonias are the perfect choice for these spaces, offering spectacular, rose-like blooms in shades of scarlet, gold, apricot, and crisp white. Whether you are looking to fill a hanging basket or brighten a garden border, these plants deliver nonstop beauty from midsummer right up until the first frost.
At Longfield Gardens, we believe that every gardener can find success with these stunning flowers. While begonias may look exotic and delicate, they are actually quite easy to grow if you get a few simple steps right. This guide is for anyone who wants to learn the best way to start these plants and keep them thriving all season long.
We will walk you through the entire process, from choosing the right spot to the specific steps for planting and care. By following these practical tips, you can enjoy a lush, professional-looking display in your own outdoor space. Learning how to plant a begonia bulb is the first step toward a more beautiful summer garden.
Understanding Begonia Bulbs and Tubers
To get the best results, it helps to know exactly what you are planting. Although most people search for "begonia bulbs," these plants actually grow from structures called tubers. A begonia tuber is a thickened, underground stem that stores energy for the plant.
When you handle a begonia tuber, you will notice it looks a bit like a small, brown, hairy potato. It has two distinct sides. One side is indented or "cupped," forming a hollow bowl shape. This is the top of the tuber where the growth points, or "eyes," are located. The other side is rounded or domed, which is the bottom where the roots will emerge.
These tubers are filled with the nutrients the plant needs to send up its first stems and leaves. Because they are tropical in origin, they are tender and cannot survive freezing temperatures. This means they need a little extra warmth to get started, but the reward is a plant that produces an incredible number of flowers for months on end.
When to Start Your Begonias
Timing is one of the most important factors for success with begonias. Because they take about 12 to 15 weeks to go from planting to full bloom, many gardeners choose to give them a head start. Starting your tubers indoors is the best way to ensure you have a full, flowering plant by early summer.
Starting Indoors
For the most flowers, we recommend starting your begonia tubers indoors about 8 to 12 weeks before your area’s last expected frost date. This usually falls in late winter or early spring. Starting them early allows the root system to establish and the first leaves to develop in a controlled, warm environment.
Planting Directly Outdoors
If you prefer to plant directly into the garden or outdoor containers, you must wait until the weather is consistently warm. Begonias are sensitive to cold soil and chilly nights. Only move them outside once the danger of frost has passed and nighttime temperatures stay reliably above 60°F. If the soil is too cold or wet, the tubers may stay dormant or fail to grow.
Key Takeaway: Starting begonias indoors in early spring leads to earlier blooms. If planting outdoors, wait until the air and soil are warm to keep the plants happy.
Choosing the Best Planting Site
Begonias are famous for their ability to bloom in the shade, but they still have specific needs regarding light and soil. Getting the "right plant in the right place" makes your job as a gardener much easier. For more detail, see this guide to how begonias grow in shade.
Light Requirements
In most climates, begonias prefer partial shade or filtered sunlight. A spot that gets soft morning sun and protection from the harsh midday heat is ideal. If they get too much direct, hot sun, the leaves can scorch or turn brown at the edges. However, they do need some light to produce those large, vivid flowers. If the shade is too deep, the plants may become "leggy" as they stretch toward the light.
Soil and Drainage
The most important rule for begonia soil is that it must drain well. These plants love moisture, but they cannot sit in soggy soil. Standing water can cause the tuber to rot.
If you are planting in the ground, look for a spot where water doesn't puddle after a rain. You can improve heavy clay soil by mixing in some compost or leaf mold. For containers, always use a high-quality potting mix that is light and airy. Ensure your pots have plenty of drainage holes so excess water can escape easily.
Preparing the Tubers for Success
Before you put your tubers in the soil, take a moment to inspect them. Healthy tubers should feel firm and heavy for their size. If they feel light, shriveled, or soft, they may not have enough energy to sprout.
Sometimes, you might see tiny pink or white buds already forming in the hollow part of the tuber. This is a great sign! These are the "eyes" waking up. If you don't see any growth yet, don't worry. Once they hit warm soil and receive a little water, they will begin to sprout.
What to do next:
- Check your frost dates to plan your start time.
- Gather light, well-draining potting soil.
- Select containers with plenty of drainage holes.
- Identify a warm, bright spot indoors for the starting phase.
Step-by-Step: How to Plant a Begonia Bulb Indoors
Starting begonias in trays or small pots is the most reliable method for beginners. It allows you to monitor the moisture levels closely while the tubers are most vulnerable. For container-specific advice, see this guide to planting begonia tubers in pots.
1. Prepare Your Containers
Fill a shallow tray or individual pots with moist potting soil. You don't need a very deep container at this stage; a depth of 3 to 4 inches is usually plenty. Leave about an inch of space at the top of the pot.
2. Position the Tuber
Place the tuber on the surface of the soil with the hollow, indented side facing up. This is the most critical step. The "bowl" should face the sky, and the rounded side should sit in the soil.
3. Set the Depth
Gently press the tuber into the soil so it is mostly covered, but leave the very top of the hollow area slightly exposed or covered by no more than half an inch of soil. Planting them too deep can make it harder for the tender sprouts to reach the surface. For more detail, read how deep to plant begonia tubers.
4. Water Lightly
Give the soil a light watering to settle it around the tuber. At this stage, the soil should be damp like a wrung-out sponge, not soaking wet. Since the tuber doesn't have roots yet, it cannot take up much water.
5. Provide Warmth and Light
Place the containers in a warm spot, ideally between 65°F and 75°F. A spot near a bright window with indirect light works well. You can cover the tray loosely with clear plastic wrap to hold in humidity, but remove it as soon as you see the first green sprouts appear.
Moving Begonias to the Garden
Once your begonias have developed several sets of leaves and the outdoor weather is warm, it is time to move them to their permanent summer home.
Hardening Off
Don't move your plants from a cozy indoor spot directly into the garden all at once. They need time to get used to the wind and changing temperatures. This process is called "hardening off." Place your pots outside in a sheltered, shady spot for a few hours each day, gradually increasing the time over a week.
Planting in the Landscape
When planting in garden beds, space the begonias about 8 to 12 inches apart. This gives them room to grow and ensures good air circulation around the leaves, which helps prevent mildew. Dig a hole just deep enough to accommodate the root ball. Set the plant in the hole so the top of the root ball is level with the surrounding soil surface.
Planting in Containers and Baskets
Begonias are the stars of the container garden. For a standard 12-inch hanging basket, you can plant two or three begonias for a full, lush look. Upright varieties work best for the center of a pot, while "pendula" or trailing varieties are perfect for the edges of baskets where they can cascade downward.
Watering and Feeding for Maximum Blooms
Begonias are hungry and thirsty plants once they start growing vigorously. Consistent care is the secret to a long blooming season.
The Right Way to Water
Check the soil daily, especially for plants in containers. The goal is to keep the soil consistently moist but never waterlogged. Stick your finger an inch into the soil; if it feels dry, it is time to water.
When you water, try to aim for the base of the plant. Avoid getting water directly on the leaves or in the center of the tuber "bowl" if you can, as this can lead to rot or fungal issues. Watering in the morning is best because it allows any stray drops on the foliage to dry out during the day.
Fertilizing Your Begonias
Because begonias bloom so much, they use up a lot of energy. We suggest using a balanced, water-soluble fertilizer every two weeks during the growing season. A formula like 20-20-20 or a bloom-boosting fertilizer with a higher middle number (phosphorus) will help the plant produce more flowers. Always follow the instructions on the product label for the correct dilution.
Key Takeaway: Consistent moisture and regular feeding are the engines that drive begonia growth. Avoid letting the soil dry out completely, and feed them every two weeks for the best show.
Maintenance and Grooming
Begonias are relatively low-maintenance, but a little grooming goes a long way in keeping them looking their best. This begonia care guide covers watering, feeding, and maintenance in more detail.
Deadheading
"Deadheading" is the practice of removing faded flowers. Most modern begonia varieties are "self-cleaning," meaning the old flowers will eventually fall off on their own. However, removing spent blooms by hand keeps the plant looking tidy and prevents the old petals from sticking to the leaves, which can sometimes cause spots.
Managing Growth
If your begonias start to look a bit leggy or thin, you can pinch back the tips of the stems. This encourages the plant to branch out and become bushier. For trailing varieties in hanging baskets, this can help create a much fuller appearance.
Protecting Against Common Issues
While begonias are generally healthy, they can sometimes face challenges like powdery mildew or stem rot. These are usually caused by too much moisture or poor air circulation.
To prevent these issues:
- Space plants properly: Don't crowd them; they need room for air to move.
- Water the soil, not the leaves: Keeping the foliage dry is the best defense against mildew.
- Ensure good drainage: Never let the pots sit in a saucer full of water.
If you see a stem that looks soft or mushy, remove it immediately to keep the rest of the plant healthy. Most problems are easily solved by adjusting your watering routine or moving the plant to a spot with better air movement.
Overwintering Your Begonia Tubers
In most parts of the United States, begonias will not survive the winter outdoors. However, you can save the tubers and replant them next year. This is a rewarding way to keep your favorite colors and see the tubers grow larger and more impressive each season. For additional seasonal context, see are begonias annuals or perennials.
When to Dig
In the fall, when the leaves begin to turn yellow or after the first light frost kills the foliage, it is time to bring them in. Cut the stems back to about an inch above the tuber.
Lifting and Drying
Gently dig up the tubers, being careful not to bruise or cut them. Shake off the excess soil and place them in a dry, shady spot (like a garage or porch) for a few days to "cure." This allows the outer skin to toughen up.
Storing for Winter
Once dry, place the tubers in a box filled with peat moss, sawdust, or shredded paper. Store the box in a cool, dark, and dry place where temperatures stay between 40°F and 50°F. A basement or a cool closet usually works well. Check on them once or twice during the winter to make sure they aren't shriveling up or getting soft.
Why Quality Matters
When you learn how to plant a begonia bulb, you quickly realize that the quality of the starting material makes a big difference. Larger tubers have more stored energy, which results in bigger plants and more flowers. At Longfield Gardens, we work with experienced growers to ensure you receive firm, healthy tubers that are ready to perform.
Our tubers are true to variety, so the colors you choose are the colors you will see in your garden. We stand behind our products with a 100% quality guarantee. If your tubers arrive damaged or do not perform as they should in their first growing season, we are here to help with a replacement or credit.
What to do next:
- Monitor your plants for faded blooms and remove them weekly.
- Keep a regular fertilizing schedule every 14 days.
- Ensure the soil stays moist during the hottest parts of summer.
- Plan your storage spot for the winter months.
Beautiful Companion Plants for Begonias
Begonias look wonderful on their own, but they also play well with other shade-loving plants. Creating a mixed display can add texture and interest to your garden. Explore more ideas in this guide to companion plants for begonias.
Foliage Plants
- Caladiums: These offer heart-shaped leaves in stunning patterns of pink, white, and green. They thrive in the same warm, shady conditions as begonias.
- Coleus: Known for its incredible leaf colors, coleus provides a vibrant backdrop for the soft textures of begonia flowers.
- Ferns: The delicate, lacy fronds of ferns provide a beautiful contrast to the bold, waxy leaves of the begonia.
Flowering Companions
- Fuchsias: In hanging baskets, fuchsias and trailing begonias make a classic, elegant pair.
- Impatiens: These can be used as a "filler" around the base of upright begonias in garden beds to create a carpet of color.
Growing Begonias as Houseplants
If you don't have a garden, you can still enjoy these plants! Tuberous begonias can be grown as temporary indoor plants. They need a very bright spot with indirect light, such as a north or east-facing window.
The care is much the same as it is outdoors: keep the soil moist and feed them regularly. While they may not bloom quite as long indoors as they do in the fresh air, they are a wonderful way to bring a splash of tropical color into your home during the summer months. See this guide to caring for begonias indoors.
Conclusion
Learning how to plant a begonia bulb is a simple skill that offers massive rewards. These plants are the champions of the shade garden, providing elegant, colorful blooms that last for months. By starting your tubers indoors, choosing a well-drained spot, and keeping up with a simple watering and feeding routine, you can create a professional-quality display with very little stress.
- Start tubers indoors 8-12 weeks before the last frost for the best results.
- Always plant the tuber with the hollow side facing up.
- Maintain consistent moisture and feed every two weeks.
- Overwinter the tubers in a cool, dry place to enjoy them again next year.
The joy of gardening comes from watching a small, unassuming tuber transform into a lush, flower-filled plant. We invite you to explore the Non Stop Begonias collection and start your own begonia journey this season.
Tuberous begonias are one of the most rewarding plants for any skill level. With just a little bit of warmth and regular water, they will reward you with a spectacular show that brightens your home and garden all summer long.
FAQ
Which side of the begonia bulb faces up?
The side with the hollow or "cupped" indentation should face up. This is where the stems and leaves will sprout. The rounded, smooth side should face down into the soil where the roots will grow.
How deep should I plant begonia tubers?
Begonia tubers should be planted just below the surface. Ideally, the top of the tuber should be covered by no more than half an inch to an inch of soil. Planting them too deep can cause the tuber to rot or prevent the sprouts from reaching the surface.
Can begonias grow in full sun?
Most tuberous begonias prefer partial shade or dappled light. In very cool, northern climates, they may tolerate more sun, but in most areas, direct midday sun will scorch the leaves and wilt the flowers. They do best with morning sun and afternoon protection.
When will my begonias start blooming?
Tuberous begonias typically start blooming about 12 to 15 weeks after they are planted. If you start them indoors in March or April, you can expect to see flowers by early to mid-July, continuing until the first frost of autumn.
