Table of Contents
- Introduction
- Understanding Tuberous Begonias
- When to Start Your Begonia Tubers
- How to Identify the Top of the Tuber
- The Pre-Sprouting Process
- Planting Begonias Indoors
- Moving Begonias Outdoors
- Choosing the Best Outdoor Location
- Watering and Feeding for Maximum Blooms
- Maintenance and Deadheading
- End of Season Care and Overwintering
- Common Begonia Questions Solved
- Growing Begonias in Different Climates
- Conclusion
- FAQ
Introduction
Imagine a shady corner of your garden transformed into a lush sanctuary filled with vibrant, rose-like blooms and tropical foliage. Tuberous begonias are the perfect choice for bringing high-impact color to areas where most flowering plants struggle to grow. These stunning plants are famous for their oversized blossoms and their ability to bloom continuously from midsummer right through the first frost of autumn.
At Longfield Gardens, we want to help you discover how easy and rewarding it is to grow these shade-loving favorites, including our Non Stop varieties. Whether you want to dress up a covered porch with hanging baskets or line a woodland path with bright borders, begonias offer endless possibilities. This guide will walk you through everything you need to know about starting your tubers and keeping them healthy all season long.
Growing begonias from tubers is a simple process that allows you to enjoy premium varieties at a great value. With a little bit of patience and the right environment, you can produce professional-quality displays right at home. Let’s look at the best ways to get your begonias started for a spectacular summer show.
Understanding Tuberous Begonias
Before you begin planting, it helps to understand what makes tuberous begonias unique. Unlike the small wax begonias often found in nursery flats, tuberous begonias grow from a thickened, underground stem called a tuber. This tuber acts as a storage unit for energy. It provides the plant with the fuel it needs to produce large, complex flowers and thick, succulent stems.
There are two primary growth habits to consider when choosing your tubers. Upright begonias grow tall and sturdy. These are ideal for garden beds or large floor pots where they can stand as a centerpiece. Cascading or trailing begonias have stems that gracefully drape downward. These are the top choice for hanging baskets and window boxes.
You will also find a variety of flower shapes. Some varieties, like the Roseform scarlet, produce blossoms that look exactly like garden roses. Others, such as the Fimbriata types, have fringed petals that resemble carnations. There are even "Non-Stop" varieties designed to produce a high volume of slightly smaller blooms all season. Knowing which type you have helps you decide on the best container and location. For more detailed care tips, see our How to Plant and Care for Begonias guide.
When to Start Your Begonia Tubers
Timing is one of the most important factors for begonia success. Because begonias are tropical plants, they are very sensitive to cold temperatures. They require a long growing season to reach their full flowering potential. If you wait until the weather is warm enough to plant them directly outside, you might not see flowers until very late in the summer.
For the best results, we recommend starting your tubers indoors about 8 to 12 weeks before your area’s last expected frost date. This gives the plants a significant head start. By the time the weather warms up, you will have well-established plants ready to bloom. In most parts of the United States, this means starting your tubers in late February or March.
If you live in a warm climate (Zones 9–11), you can plant tubers directly into the ground once the soil has warmed. However, even in warm regions, starting them in pots allows you to control the environment and protect the young sprouts from heavy spring rains.
Key Takeaway: Start begonia tubers indoors 8–12 weeks before the last frost to ensure a long, productive blooming season.
How to Identify the Top of the Tuber
One of the most common questions gardeners ask is which side of the begonia tuber should face up. When you look at a tuber, it usually looks like a dark brown, slightly hairy disk or a small bowl. One side will be slightly indented or hollowed out, while the other side is rounded.
The indented, bowl-shaped side is the top. This is where the new leaf sprouts will emerge. The rounded side is the bottom, where the roots will form. If you look closely at the hollow side, you might see small, pinkish buds or "eyes" starting to wake up.
If you happen to find a tuber that is perfectly flat and you cannot tell the difference, you can plant it on its side. The plant is smart enough to send roots down and shoots up. However, placing the hollow side up is the preferred method for the fastest growth.
The Pre-Sprouting Process
You do not have to wait until you are ready to pot the begonias to start waking them up. Pre-sprouting is an easy way to get the growth process moving. This step is particularly helpful if your indoor space is limited and you aren't ready to commit to large pots just yet.
To pre-sprout your begonias, find a shallow tray and fill it with an inch of moist potting soil or peat moss. Place the tubers on the surface with the hollow side facing up. You do not need to cover them completely at this stage. Place the tray in a warm room (about 70°F) with indirect light. If you need a deeper explanation, our How Deep Should I Plant Begonias guide is a helpful reference.
Within two to four weeks, you will see small red or green sprouts emerging from the center of the tuber. Once these sprouts are about an inch tall, it is time to move the tubers into their individual pots or final containers. This simple "warm-up" period ensures that every tuber you plant is healthy and active.
Planting Begonias Indoors
When you are ready to pot your tubers, choose a high-quality potting mix. Begonias need soil that is light and well-draining. "Drainage" refers to how fast water leaves the soil. If the soil stays too wet, the tuber can rot before it even has a chance to grow.
Selecting Containers
For individual tubers, an 8-inch pot is a great starting size. If you are using a large decorative planter, you can plant multiple tubers together. Just make sure they are spaced about 6 to 10 inches apart so they have room to spread. Every container must have drainage holes at the bottom. A plant like Begonia Upright Double Roseform Pink is a classic example of a tuberous begonia that performs beautifully in containers.
Planting Depth and Placement
Fill your container with moist potting soil, leaving about two inches of space at the top. Place the tuber in the center with the hollow side up. Cover the tuber with about one inch of soil. You do not want to bury them too deeply. Being close to the surface allows the sprouts to reach the light quickly.
Initial Watering
Water the soil lightly after planting. You want the soil to feel like a wrung-out sponge. It should be damp but never muddy. Place the pots in a spot with bright, indirect light. A windowsill that gets morning sun is perfect. Avoid placing them in a dark corner or a spot with harsh, direct midday sun, which can scorch tender new leaves.
What to do next:
- Check the soil every few days by poking your finger an inch deep.
- Water only when the surface feels dry to the touch.
- Keep the room temperature above 60°F.
- Rotate the pots once a week so the plants grow straight rather than leaning toward the light.
Moving Begonias Outdoors
Transitioning your begonias from the cozy indoors to the garden requires a bit of care. This process is called "hardening off." Because begonias have succulent, water-filled stems, they can be damaged by sudden changes in temperature or wind.
Wait until all danger of frost has passed and nighttime temperatures are consistently above 50°F to 60°F. If you put them out too early, the cold can stunt their growth for the rest of the season. Start by placing your pots in a sheltered, shady spot outside for a few hours each day. Gradually increase the time they spend outdoors over the course of a week. For zone-specific timing, use our Hardiness Zone Map.
If you are transplanting your begonias into garden beds, dig a hole slightly larger than the root ball. Carefully slide the plant out of its pot and place it in the hole. A helpful tip for upright begonias: notice which way the leaves are pointing. The flowers usually face the same direction as the tips of the leaves. Point the leaves toward your favorite viewing spot so the flowers face you!
Choosing the Best Outdoor Location
The "right plant, right place" rule is essential for begonias. They are famous for being shade plants, but they do need some light to produce flowers. The goal is to find a balance between light and protection. Our Where to Plant Begonias: Sun or Shade? guide covers this in more detail.
Sunlight Needs
Begonias love filtered light or "dappled shade," such as the light found under a tall tree. Morning sun is usually fine because it is cool. However, the hot, direct sun of the afternoon can burn the foliage and cause the flowers to drop. If you live in a very hot climate, your begonias will need almost total shade during the heat of the day.
Air Circulation
While begonias like humidity, they also need fresh air. Avoid crowding them into tight corners where the air is stagnant. Good air circulation helps prevent common issues like powdery mildew, which looks like a dusting of white flour on the leaves.
Wind Protection
Tuberous begonias have brittle stems that can snap in heavy winds. Choose a spot that is sheltered from strong gusts. If you are growing tall, upright varieties with massive flowers, you might want to provide a small bamboo stake for extra support.
Key Takeaway: Place begonias in a spot with morning sun and afternoon shade, ensuring they are protected from strong winds.
Watering and Feeding for Maximum Blooms
Begonias are "water-wise" in a specific way. Their thick stems and tubers store water, which means they don't need to be soaked constantly. However, they also don't like to dry out completely. For a deeper look at moisture needs, read How Much Water Does a Begonia Plant Need?.
The Finger Test
The best way to water is to use the "deep, then dry" method. Water the plant thoroughly until water runs out of the drainage holes. Then, wait to water again until the top inch of soil feels dry to the touch. In the heat of summer, you may need to check them daily, especially if they are in hanging baskets.
How to Apply Water
Try to water at the base of the plant rather than splashing the leaves. Wet foliage can lead to fungal issues. If you can, water in the morning so any moisture on the leaves has time to dry before the sun goes down.
Fertilizing Your Begonias
Begonias are heavy feeders. They are working hard to produce those giant blooms, and they need regular nutrients. Once the plant has several sets of leaves, start using a balanced, water-soluble fertilizer.
A "quarter-strength" approach works best. This means using one-fourth of the recommended amount on the package but applying it more frequently—about once a week. This provides a steady stream of food without the risk of burning the tender roots. If you see lots of leaves but no flowers, switch to a fertilizer with a higher middle number (phosphorus), which encourages bloom production.
Maintenance and Deadheading
To keep your begonias looking their best, you will need to do a little "housekeeping" throughout the summer. This isn't hard work; it’s actually a great way to spend a few minutes enjoying your garden.
Deadheading Flowers
"Deadheading" means removing flowers that have faded or begun to wilt. When a flower starts to look spent, snap it off where it meets the main stem. This prevents the plant from putting energy into producing seeds and encourages it to grow new buds instead.
Removing Yellow Leaves
If you see yellow or damaged leaves, go ahead and remove them. This keeps the plant looking tidy and improves air circulation. Begonias naturally drop some of their smaller male flowers, so don't worry if you see a few blossoms on the ground—it's just the plant's way of thinning itself out.
Staking Upright Varieties
If you are growing the "Superba" or "Roseform" types, the flowers can become so large and heavy that they pull the stems down. Use a small bamboo stake and a soft tie to gently secure the main stem. Do this early in the season so the plant grows up against the support.
End of Season Care and Overwintering
One of the best things about tuberous begonias is that they can live for many years. When the weather turns cold in the autumn, the plants will naturally begin to slow down. The leaves might turn yellow, and fewer flowers will appear. This is your signal that the tuber is preparing for a nap.
Preparing for Dormancy
As the first frost approaches, stop fertilizing and reduce your watering. Let the soil dry out. If your begonias are in the ground and you live in a cold zone (Zones 3–8), you must dig them up to save them. If they are in pots, you can simply move the entire pot into a frost-free area like a garage or basement. Our Shipping Information page is also useful when you’re planning purchases by season and zone.
Storing the Tubers
Once the foliage has turned yellow or been hit by a light frost, cut the stems back to about an inch above the tuber. Lift the tubers out of the soil and gently shake off the excess dirt. Let them sit in a dry, sunny spot for a few days to "cure" or toughen up their outer skin.
Store the dry tubers in a cardboard box or paper bag filled with peat moss, vermiculite, or even shredded newspaper. Keep them in a cool, dark, and dry place where temperatures stay between 40°F and 50°F. Check on them once a month during the winter. If they look shriveled, give them a tiny mist of water. If they look soft or moldy, remove the affected ones to keep the others healthy.
What to do next:
- Mark your calendar to dig up tubers before the first hard freeze.
- Clean the tubers gently; do not scrub them.
- Label your storage bags by color or variety.
- Store them away from fruits like apples, which can cause them to rot.
Common Begonia Questions Solved
Even with the best care, you might run into a few questions as you grow your begonias for the first time. Most issues have very simple solutions.
Why are the flower buds falling off?
This usually happens because of a change in environment. If the soil gets too dry, or if the air becomes extremely hot and dry, the plant may drop its buds to conserve moisture. Try to keep the soil consistently moist and move the plant to a cooler, shadier spot if the summer heat becomes intense.
Why does the plant have leaves but no flowers?
This is often a light issue. While begonias hate the direct midday sun, they do need bright light to bloom. If they are in deep, dark shade, they will grow beautiful green leaves but won't have the energy to flower. Move the pot to a spot with more filtered morning sun. It can also be caused by too much nitrogen in your fertilizer; try switching to a bloom-boosting formula. For extra background, our Begonia Learn page is a helpful place to explore related guides.
What are these white spots on the leaves?
This is likely powdery mildew. It usually happens when the air is humid and still. You can help the plant by moving it to a spot with better air movement. You can also mix a simple solution of one tablespoon of baking soda and a few drops of mild soap in a gallon of water and spray it on the leaves to help manage the fungus. If you ever have questions about your order or gardening resources, visit our About Us page.
Growing Begonias in Different Climates
Your experience with begonias will vary slightly depending on where you live. At us, we see our customers succeed across the country by making small adjustments to the "Right Plant, Right Place" rule.
Hot and Humid Climates
In the South, begonias need much more shade. The morning sun can be intense even at 9:00 AM. Look for the coolest spot in your yard, such as the north side of your home. You will also need to be more vigilant about air circulation to prevent rot in the high humidity.
Dry and Windy Climates
In the West, the biggest challenge is dry air. Begonias love humidity. You can create a "microclimate" by grouping your pots together. As the plants breathe, they release moisture, which helps the plants next to them. You may also need to water more frequently since pots dry out fast in low humidity.
Short-Season Climates
In the North, starting indoors is not just a suggestion—it is a requirement. Because your summers are shorter, you need the plants to be "ready to go" the moment the soil warms up. Using a heat mat under your seed trays can help wake up the tubers faster in a cold house.
Conclusion
Growing begonias from tubers is one of the most satisfying projects a gardener can undertake. From the moment that first tiny red sprout appears to the day your garden is filled with massive, colorful blooms, the process is full of excitement. By focusing on the basics—starting early, providing filtered light, and ensuring good drainage—you can enjoy a spectacular display that lasts for months.
- Start your tubers indoors 8–12 weeks before the last frost.
- Plant the hollow side up and cover with an inch of soil.
- Wait for warm nights before moving plants outside.
- Water when the top inch of soil is dry and feed regularly with liquid fertilizer.
Tuberous begonias bring a touch of the tropics to any home, and they are surprisingly easy to maintain once you get the timing right. We at Longfield Gardens are here to support you with quality tubers and the advice you need to see them thrive.
"There is a unique joy in watching a dry, brown tuber transform into a lush, flowering masterpiece. Tuberous begonias remind us that with a little patience and the right care, even the shadiest corners of our lives can burst into brilliant color."
Take the first step toward your most beautiful shade garden yet by selecting your favorite begonia varieties today. With our 100% quality guarantee, you can plant with confidence and look forward to a summer filled with stunning blooms.
FAQ
Can I grow tuberous begonias in full sun?
Tuberous begonias generally prefer partial shade or filtered light. In most climates, full sun will scorch their leaves and cause the flowers to wilt or drop. However, if you live in a very cool, coastal climate with lots of fog, they may tolerate more sun. For most gardeners, morning sun and afternoon shade is the winning combination.
Why is my begonia tuber not sprouting?
Begonia tubers can be slow to wake up, sometimes taking 4 to 6 weeks. Ensure the tuber is in a warm spot (around 70°F) and that the soil is moist but not soaking wet. If the room is too cold, the tuber will stay dormant. Give it time, as some varieties are simply "late sleepers" compared to others.
Do I need to peel the skin off the tuber before planting?
No, you should never peel or scrub the tuber. The dark, papery skin is a natural protective layer. Simply handle the tuber gently to avoid snapping off any brittle sprouts that may have already started to grow. If there are old, dried roots from last year, you can leave them alone; new roots will grow right past them.
How many tubers should I put in one hanging basket?
For a standard 12-inch hanging basket, three tubers are usually perfect. This allows the plants enough room to grow without being overcrowded, but it's enough to create a full, lush look that spills over the sides. If you are using exceptionally large tubers, two may be sufficient to fill the space by midsummer.
Why are my begonia leaves turning yellow and falling off?
Yellowing leaves are usually a sign of overwatering or poor drainage. If the soil stays soggy, the roots can't "breathe," which leads to yellowing foliage and eventually tuber rot. Always check the soil with your finger before watering. If the soil is wet and the leaves are yellow, stop watering immediately and let the pot dry out before the next drink.