Table of Contents
- Introduction
- Understanding the Different Types of Begonias
- When is the Best Time to Plant?
- Choosing the Best Location
- How to Plant Tuberous Begonias
- Planting Wax and Foliage Begonias
- Growing Begonias in Containers
- Caring for Your Begonias All Summer
- Realistic Expectations for Your Garden
- Saving Tubers for Next Year
- Conclusion
- FAQ
Introduction
Finding the perfect flower for a shady corner can feel like discovering a hidden treasure. While many blooming plants demand hours of intense, direct sunlight, begonias thrive in the soft, filtered light of a porch, a covered patio, or beneath the canopy of a tall tree. At Longfield Gardens, we enjoy these plants because they offer a reliable explosion of color and lush texture from the moment summer arrives until the first frost of autumn.
Whether you are looking for the massive, rose-like blooms of tuberous begonias or the colorful, patterned leaves of Rex varieties, planting them is a rewarding process that any gardener can master. This guide will walk you through everything you need to know, from choosing the right spot to the simple steps for tucked-in success. By focusing on a few basics like timing and soil moisture, you can enjoy a season full of vibrant, healthy begonias.
Getting begonias off to a strong start is the best way to ensure a long season of beauty in your garden or on your patio.
Understanding the Different Types of Begonias
Before we dig into the soil, it is helpful to know which type of begonia you are planting. While there are thousands of varieties, most home gardeners choose from three main groups. Identifying yours helps you provide the specific care it needs to flourish.
Tuberous Begonias
These are the superstars of the shade garden. They grow from a thickened, potato-like underground stem called a tuber. Tuberous begonias are famous for their large, dramatic flowers that come in nearly every color except blue. You can find upright varieties that stand tall in garden beds and trailing varieties (often called pendula) that spill beautifully over the edges of hanging baskets. We ship these as dormant tubers ready for spring planting.
Wax Begonias
You likely recognize these as the classic bedding plants found in parks and front borders. They have fibrous roots and smaller, succulent-like leaves that are either bright green or a deep bronze. Wax begonias are incredibly tough and can handle a bit more sun than their tuberous cousins. They are usually purchased as established plants in nursery flats.
Rex and Rhizomatous Begonias
These varieties are grown primarily for their stunning foliage rather than their flowers. Their leaves can feature swirls of silver, purple, pink, and emerald green. They grow from thick stems called rhizomes that creep along the soil surface. While they are often kept as houseplants, they make excellent additions to shaded outdoor containers during the warm summer months.
Key Takeaway: Tuberous begonias offer the largest flowers and are planted from dormant bulbs, while wax begonias are small, sturdy bloomers usually planted as seedlings.
When is the Best Time to Plant?
Begonias are tropical plants by nature, which means they have no love for the cold. Timing is everything when it comes to a healthy start. If you plant them too early in cold, damp soil, the tubers may struggle to wake up.
Wait for the Warmth
The most important rule for begonias is to wait until all danger of frost has passed. The soil should feel warm to the touch—ideally around 60°F. In most parts of the United States, this means waiting until late May or early June to move your plants outdoors. If the nights are still dipping below 50°F, it is best to keep your begonias in a protected area.
Starting Indoors for an Early Show
If you want your begonias to start blooming as soon as summer arrives, you can give them a head start indoors. About 8 to 12 weeks before the last expected frost in your area, you can plant your tubers in small pots or a shallow tray. Keep them in a warm, bright spot (but out of direct, hot sun). This extra time allows the tubers to develop roots and sprout leaves so that by the time the weather warms up, you are transplanting a vigorous plant rather than a dormant tuber.
Shipping and Hardiness Zones
We time our shipments based on your USDA hardiness zone to ensure your tubers arrive at the right time for your climate. Begonias are only hardy in zones 9–11. In all other regions, they are treated as annuals or brought indoors for the winter. Knowing your zone helps you plan your "frost-free" date with more confidence.
Choosing the Best Location
Matching your begonias to the right spot in your yard is a simple way to prevent stress for the plant. When you get the light and soil right from day one, the rest of the season becomes much easier.
Light Requirements: Filtered and Fair
Most begonias prefer "dappled" or filtered sunlight. Think of the light that filters through the leaves of a large tree or the bright but indirect light on a north-facing porch.
- Morning Sun: A few hours of gentle morning sun followed by afternoon shade is often the "sweet spot."
- Intense Heat: Avoid placing begonias in spots where they will be baked by the harsh afternoon sun, especially in southern climates. This can cause the leaves to scorch or the flowers to wilt.
- Deep Shade: While they love shade, begonias still need some light to produce flowers. If a spot is so dark that moss is the only thing growing there, your begonias might produce plenty of leaves but very few blooms.
Soil and Drainage
"Drainage" simply refers to how quickly water moves through the soil. Begonias have fleshy stems that store water, which makes them susceptible to rot if they sit in a puddle.
- The Soil Test: If you have an area where water stands for several hours after a heavy rain, that spot is too wet for begonias.
- Improving the Site: You can improve heavy clay soil by mixing in organic matter like compost or finely ground bark. This creates "air pockets" in the soil, allowing the roots to breathe and water to flow away.
- Containers: If your garden soil is difficult to work with, begonias are the perfect candidates for pots and window boxes. Always use a high-quality, well-draining potting mix.
How to Plant Tuberous Begonias
Planting a tuber is a bit different from planting a traditional round bulb like a tulip. If you look closely at a begonia tuber, you will see it has a unique shape that tells you exactly how it wants to be positioned.
Step 1: Identify "Up"
One side of the begonia tuber is slightly indented or concave—it looks a bit like a shallow bowl or a belly button. This indented side is the top. This is where the new stems and leaves will sprout. The rounded, smoother side is the bottom, where the roots will grow.
Step 2: Prepare the Soil
Whether you are planting in a garden bed or a container, loosen the soil first. If you are using a pot, ensure it has drainage holes at the bottom. A mix of potting soil and a little compost provides the nutrients these hungry bloomers need.
Step 3: Planting Depth and Spacing
Begonias do not need to be buried deep. In fact, planting them too deep is a common reason they might fail to sprout.
- Depth: Place the tuber into the soil so it is covered by only about 1 inch of soil. Some gardeners even leave the very top of the tuber exposed until they see the first sprouts, then add a light dusting of soil over it.
- Spacing: Space your tubers about 8 to 12 inches apart. This gives each plant enough room to spread out and ensures there is plenty of airflow between the leaves, which helps prevent mildew.
Step 4: The First Water
After tucking your tubers in, give them a light drink of water to settle the soil. However, be careful not to overwater at this stage. Until the tuber has developed roots and started to grow leaves, it cannot "drink" much water. Keeping the soil slightly damp—like a wrung-out sponge—is better than keeping it soaking wet.
What to do next:
- Check your tubers for the indented "top" side.
- Loosen the soil to a depth of about 5–6 inches.
- Set the tuber 1 inch deep with the "bowl" side up.
- Water once and then wait for sprouts to appear.
Planting Wax and Foliage Begonias
If you have purchased wax begonias or Rex begonias from a local nursery, the process is even simpler. These arrive as active, growing plants in plastic pots.
Preparing the Root Ball
Gently squeeze the sides of the nursery pot to loosen the plant. As you slide the begonia out, look at the roots. If they are tightly circling the bottom of the pot, gently tease them outward with your fingers. This encourages the roots to grow out into their new soil rather than continuing to grow in a circle.
Planting Level
Dig a hole that is the same depth as the nursery pot. When you set the plant in the hole, the top of the root ball should be exactly level with the surrounding soil. Avoid burying the stems, as this can lead to rot. Firm the soil gently around the base of the plant to remove large air pockets.
Watering In
Because these plants already have a full set of leaves, they will be thirstier than a dormant tuber. Water them immediately after planting to help the roots establish a connection with the new soil.
Growing Begonias in Containers
Begonias and containers are a match made in heaven. Because you can control the soil quality and move the pots to find the perfect light, container gardening is often the easiest way to succeed with these plants.
Choosing the Right Pot
You can plant begonias in almost anything, from ceramic pots to plastic hanging baskets or wooden window boxes. The only requirement is a drainage hole. For a standard 12-inch pot, you can plant about three tuberous begonias for a full, lush look.
The "Slight Angle" Trick
If you are planting tuberous begonias in an area that gets a lot of rain, try planting the tuber at a very slight angle rather than perfectly flat. This prevents water from "pooling" in the indented center of the tuber, which reduces the risk of the tuber rotting before it sprouts.
Upright vs. Trailing
When choosing your varieties, think about where the pot will sit.
- Upright Varieties: Varieties like 'Nonstop' stay compact and mounded, making them great for pots that sit on a table or the ground.
- Trailing Varieties: Varieties like 'Illumination' or 'Cascading' have stems that grow outward and then drape down. These are the best choice for hanging baskets or the edges of window boxes where they can create a "curtain" of flowers.
Caring for Your Begonias All Summer
Once your begonias are established and growing, they are relatively low-maintenance. A little consistent attention will keep them blooming beautifully until the end of the season.
Water Correctly, Not Constantly
Begonias like "consistent moisture," but they hate "wet feet."
- The Finger Test: Stick your finger into the soil up to the second knuckle. If the soil feels dry, it is time to water. If it still feels moist, wait a day or two.
- Water the Soil, Not the Leaves: Whenever possible, direct your watering can at the base of the plant. Wetting the leaves can encourage fungal issues like powdery mildew, especially in humid weather.
Feeding Your Plants
Begonias are heavy feeders. They put a lot of energy into creating those spectacular blooms.
- Fertilizing: Use a balanced, water-soluble fertilizer every two to three weeks.
- Follow the Label: Always follow the instructions on the fertilizer package. It is better to use a slightly weaker solution more often than to use too much at once.
Grooming for Beauty
Most modern begonias are "self-cleaning," meaning the old flowers will eventually fall off on their own. However, you can keep the plants looking their best by "deadheading"—pinching off any faded blooms or yellowing leaves. This keeps the plant’s energy focused on creating new buds rather than trying to maintain old ones.
What to do next:
- Water when the top inch of soil feels dry.
- Apply a liquid fertilizer every 2 weeks during the blooming season.
- Pinch off spent flowers to keep the plant looking tidy.
- Monitor for afternoon sun and move containers to a shadier spot if leaves look scorched.
Realistic Expectations for Your Garden
Gardening is a partnership with nature, and results can vary based on your local conditions. It is important to remember that begonias are slow starters. If you plant a tuber and don't see green sprouts for three or four weeks, don't worry! They need the soil to be consistently warm to wake up. Once they start growing, they pick up speed quickly.
The size of the flowers and the height of the plant will also depend on your climate. In very hot, humid areas, begonias might take a short "break" from blooming during the hottest part of July and then resume their show once the temperatures drop slightly in late August. This is a natural response to heat and not a sign that you have done anything wrong.
Saving Tubers for Next Year
One of the best things about tuberous begonias is that you can save them and plant them again next year. As the days grow shorter in the fall, the plants will naturally begin to slow down.
Before the First Frost
When the leaves start to turn yellow or after the first very light frost, it is time to bring them in.
- Stop Watering: Let the soil dry out completely.
- Lifting the Tubers: Carefully dig the tubers out of the garden or remove them from their pots.
- Drying: Cut the stems back to about an inch above the tuber. Let the tubers sit in a dry, protected spot for a few days until any remaining soil can be easily brushed off.
- Storage: Place the clean tubers in a paper bag or a box filled with peat moss or sawdust. Store them in a cool (about 50°F), dark, dry place like a basement or closet until next spring.
Conclusion
Planting begonias is one of the easiest ways to bring high-impact color to the shaded parts of your landscape. By choosing a well-drained spot with filtered light and waiting for the warm weather of late spring, you set the stage for a spectacular display. Whether you plant them in a grand garden border or a simple pot on your porch, these versatile plants will reward you with months of effortless beauty.
At Longfield Gardens, our goal is to help you feel confident in your garden. We stand behind the quality of our tubers with our 100% Quality Guarantee and are here to support you as your garden grows. Remember that gardening is a journey of observation and enjoyment. Take the time to watch those first sprouts emerge and enjoy the vibrant colors that only begonias can provide.
Success with begonias comes down to three things: warm soil, dappled shade, and a light touch with the watering can. Get these right, and your shade garden will be the highlight of your yard.
Take the next step toward a beautiful shade garden by selecting a few of your favorite varieties and planning your planting date for after the last spring frost.
FAQ
How deep should I plant begonia tubers?
Begonia tubers should be planted quite shallowly, with only about 1 inch of soil covering the top of the tuber. If you plant them too deep, the sprouts may struggle to reach the surface, or the tuber may rot before it has a chance to grow.
Which side of the begonia tuber faces up?
The side with the "belly button" or concave indentation should face upward. This is where the stems will sprout. The rounded, smoother side should face down into the soil so the roots can grow downward.
Can begonias grow in full sun?
Most begonias, especially tuberous and Rex varieties, prefer partial shade or filtered light and will scorch in direct afternoon sun. However, wax begonias—the ones with the shiny, succulent leaves—are much more tolerant of sunlight and can often handle full sun if they are kept consistently moist.
Why are my begonia tubers not sprouting?
The most common reason begonias are slow to sprout is cool soil temperatures. Begonias need consistent warmth (60°F or higher) to wake up from dormancy. It can often take 3 to 4 weeks for the first green tips to appear, so a little patience is usually all that is required.