Introduction
There is a unique excitement that comes with planning a summer garden filled with lush foliage and vibrant, rose-like blooms. Begonias are a favorite for many of us because they bring reliable, high-impact color to the shadiest corners of the yard. Whether you are tucking them into a classic window box or hanging them from a porch, the reward of a well-timed planting is a season-long display that only gets better as the weeks go by.
At Longfield Gardens, we want to help you get the best results from our bulbs and tubers. Many gardeners wonder exactly when the right moment is to move these tropical beauties outside. Because begonias love warmth, timing is the most important factor in ensuring they thrive and bloom early.
This guide will explain the ideal temperature windows for planting, how to transition your plants safely, and how your local climate dictates your gardening schedule. By matching your planting date to the specific needs of the begonia, you can enjoy a garden that is full of life from early summer until the first frost of autumn.
The Best Time to Plant Begonias Outdoors
The most important rule for planting begonias is to wait for the warmth. These plants are tropical in origin, which means they have no tolerance for frost and very little patience for cold soil. For most home gardeners in the United States, the window for moving begonias outdoors typically opens in late spring or early summer.
Specifically, you should wait until the danger of frost has completely passed. Even a light, "patchy" frost can damage the tender succulent stems and leaves of a begonia. However, frost isn't the only metric to watch. Begonias perform best when the soil temperature has reached at least 60°F. If the ground is still cold and damp from spring rains, the tubers may sit dormant or, in the worst-case scenario, begin to struggle before they even sprout.
A good rule of thumb is to watch the nighttime temperatures. When the nights are consistently staying above 50°F to 60°F, your begonias will feel right at home. In many northern states, this might not happen until late May or even the first week of June. In the South, you may be able to plant as early as March or April, depending on your specific location.
Key Takeaway To ensure your begonias grow quickly and stay healthy, wait until the soil is 60°F and nighttime air temperatures are consistently above 50°F.
Understanding Your Planting Window by Region
Because the United States covers so many different climates, "spring" means something very different in Maine than it does in Georgia. We use USDA hardiness zones to help determine when it is safe to ship and plant.
- Zones 3-7: In these cooler regions, begonias are grown as annuals. You will likely be planting outdoors in late May or June. Because the growing season is shorter, many gardeners in these zones choose to start their tubers indoors to get a head start on the blooming season.
- Zones 8-11: In these warmer climates, begonias can sometimes survive the winter in the ground if the soil stays relatively dry. Planting can happen much earlier here, often as soon as the soil warms in early spring.
We time our shipments at Longfield Gardens to arrive at the appropriate planting time for your specific zone. This helps ensure that your tubers arrive when the conditions in your area are becoming favorable for growth. When your package arrives, check the local forecast. If an unexpected cold snap is predicted, it is perfectly fine to keep your tubers in a cool, dry place for another week or two until the weather settles.
Why Soil Temperature Matters More Than the Calendar
It can be tempting to plant on a specific holiday, like Mother's Day or Memorial Day, but the plants respond to the environment, not the date. Begonias are essentially built of water; their stems are thick and juicy, which makes them very sensitive to the "chill factor."
If you plant into cold soil (below 50°F), the tuber enters a protective state. It won't send out roots, and the moisture in the soil can cause the tuber to soften. By waiting just one or two extra weeks for the soil to warm up, you often see the plant "catch up" and actually grow faster than a plant put in the ground too early.
You can check your soil temperature with a simple garden thermometer, or simply use the "touch test." If the soil feels uncomfortably cold to your bare hand, it is likely too cold for a begonia tuber.
Starting Begonias Indoors for Earlier Blooms
If you live in a northern climate and want to see flowers as early as June, starting your begonias indoors is a great strategy. This "pre-starting" process usually begins about 8 to 12 weeks before the last expected frost date in your area.
By starting them in small pots on a sunny windowsill or under grow lights, you allow the tuber to develop a strong root system and its first set of leaves while it is still too cold outside. By the time the outdoor temperatures are safe, you aren't just planting a tuber—you are transplanting a vigorous young plant that is ready to start budding.
When to Move Indoor Starts Outside
When you have started your begonias indoors, you cannot move them directly into the full outdoor environment all at once. They have been living in a controlled, "soft" environment and need to be toughened up. This process is called hardening off.
- Start slow: About 10 days before you plan to plant, set the pots outside in a fully shaded, wind-protected spot for just 2 or 3 hours.
- Increase exposure: Each day, leave them out for an hour or two longer.
- Monitor light: Gradually introduce them to the level of light they will have in their permanent home.
- Final move: Once they can spend a full 24 hours outside without wilting or showing signs of stress, they are ready to be tucked into the garden.
Choosing the Right Spot for Outdoor Planting
When the time finally comes to plant, the "where" is just as important as the "when." Begonias have specific preferences for light and air movement that will determine how many flowers you see.
Light Requirements
Most begonias, especially the tuberous varieties we carry, prefer filtered light or partial shade. In the wild, they grow under the canopy of trees where they receive "dappled" sunlight. For more guidance, see this begonia light and shade guide.
- Morning Sun: A spot that gets 3–4 hours of gentle morning sun followed by afternoon shade is often the "sweet spot."
- Deep Shade: While begonias are famous shade-lovers, they do need some light to produce flowers. If the area is too dark, the plants may become "leggy" (tall and thin) and produce fewer blooms.
- Harsh Afternoon Sun: Avoid spots that get direct, hot sun from 12:00 PM to 4:00 PM. This can scorch the leaves and cause the flowers to wilt prematurely.
Drainage and Soil Quality
Begonias hate "wet feet." This means they need soil where water moves through quickly. If you are planting in the ground, adding some compost or organic matter can help improve the soil structure. If you are planting in containers, always use a high-quality potting mix and ensure the pot has at least one drainage hole. This guide to planting begonias in containers covers soil, drainage, and container preparation in more detail.
What to Do Next
- Identify your last frost date and count back 8 weeks if you want to start indoors.
- Prepare your pots or garden beds with fresh, well-draining soil.
- Monitor the 10-day weather forecast for consistent nighttime temperatures above 50°F.
Step-by-Step Guide to Planting Begonia Tubers
Once the weather is right and your site is ready, planting is a simple and rewarding task. Getting the depth and orientation right is the key to a successful start.
1. Identify the Top of the Tuber
Begonia tubers have a distinct look. One side is usually rounded, while the other has a slight hollow or "bowl" shape. The hollow side is the top. This is where the new sprouts will emerge. If you see small pink "nubs" or sprouts already forming, those should always point upward. For a closer look, see this begonia tuber orientation guide.
2. Set the Depth
You do not need to bury begonias deeply. In fact, planting them too deep can slow down their growth.
- Dig a shallow hole.
- Place the tuber inside with the hollow side facing up.
- Cover with only about 1 inch of soil.
3. Spacing for Success
Begonias like a bit of elbow room for air to circulate around their leaves.
- For garden beds, space tubers about 8 to 12 inches apart.
- For containers, you can plant them a bit closer—about 3 tubers in a 12-inch pot—to create a full, lush look.
4. The First Watering
After planting, water the soil lightly to help it settle around the tuber. However, be careful not to overwater at this stage. Until the tuber has developed leaves, it isn't "drinking" much water. Keeping the soil slightly damp but not soaked is the best way to prevent the tuber from rotting before it gets started.
Matching the Type of Begonia to Your Planting Plan
Different begonias have different growth habits, and knowing which one you have will help you decide when and where to plant them.
Tuberous Begonias (Upright)
These are the stars of the shade garden, producing large, rose-like flowers. Because they grow 12 to 18 inches tall, they are perfect for the front of a garden border or the center of a patio pot. They should be planted when the weather is warm and stable. Longfield Gardens also offers a Non Stop Begonias collection.
Tuberous Begonias (Trailing/Pendula)
These varieties have stems that naturally cascade downward. They are designed for hanging baskets and window boxes. Because hanging baskets are more exposed to the wind and air, they can dry out faster and stay cooler than the ground. If you are hanging these outdoors, you might wait an extra few days until the nights are truly warm.
Wax Begonias
These are often sold as small "plugs" or bedding plants. They have waxy leaves and smaller, prolific flowers. Wax begonias are a bit more tolerant of sun than tuberous varieties, but they still need to wait for the frost-free date before they go into the ground.
Factors That Can Delay Your Planting Time
Even if the calendar says it's time to plant, nature sometimes has other plans. It is always better to be flexible than to force a planting into bad conditions.
- Heavy Spring Rains: If your garden beds are saturated and "mucky," wait for them to dry out. Planting in waterlogged soil is a recipe for tuber rot.
- High Winds: If you are transplanting begonias that were started indoors, a very windy day can snap their brittle stems. Wait for a calm, overcast day to move them outside.
- Extreme Heat: If an early-season heatwave hits (90°F+), wait until it passes. Moving a young plant into extreme heat causes significant transplant shock.
Caring for New Plantings in Early Summer
The first few weeks after your begonias move outdoors are a critical time for establishment. During this phase, the plant is focusing its energy on growing roots into the new soil.
Watering Correctly
The goal is "deep, then dry." Instead of giving the plants a tiny sip of water every day, give them a thorough soaking until water runs out of the bottom of the pot (or the soil is wet several inches down). Then, wait until the top inch of soil feels dry to the touch before watering again. This encourages the roots to grow deeper in search of moisture.
Feeding Your Plants
Begonias are "heavy feeders," meaning they use a lot of energy to produce those big, beautiful flowers. Once you see active growth and several sets of leaves, you can begin using a balanced, water-soluble fertilizer. Many gardeners find that fertilizing every two weeks provides the consistent nutrients the plant needs to keep blooming all the way through September.
Troubleshooting Early Season Issues
If your begonias aren't blooming right away, don't worry. They often focus on leaf growth first. As long as the leaves look healthy and green, the flowers will follow as the days get longer and warmer. If you notice yellowing leaves, it is often a sign of overwatering. Simply let the soil dry out more between waterings and the plant will usually recover on its own.
The Excitement of the First Bloom
The wait for the right weather pays off the moment those first buds begin to unfurl. Tuberous begonias offer a variety of flower shapes—from the ruffled "Fimbriata" types to the sleek, bicolor "Marmorata" varieties. One of the best things about begonias is that they are "self-cleaning," meaning most varieties will drop their old flowers naturally, so you don't have to spend your summer deadheading.
As the summer progresses, the plants will become more robust. By mid-August, a well-timed begonia planting will be a centerpiece of the garden, providing color when other spring-blooming plants have long since faded.
Transitioning to Fall
While the focus is usually on planting out, it is helpful to keep the end of the season in mind. When temperatures begin to drop back into the 40s in the autumn, begonias will start to slow down. Their leaves may turn yellow, which is a signal that the plant is moving energy back into the tuber for the winter.
In most parts of the country, this is the time to dig up the tubers and store them in a cool, dry place like a basement or garage. By protecting the tubers from the freezing winter ground, you can replant the exact same begonias next spring, often with even better results as the tubers grow larger each year. For regional guidance, see the begonia growing zone guide.
Conclusion
Getting the timing right for your begonias is one of the simplest ways to ensure a successful gardening season. By prioritizing soil warmth and waiting for the frost to pass, you give these tropical beauties the environment they need to flourish. Whether you choose to start them indoors for an early show or plant them directly into your garden beds in June, the result will be a stunning display of color that lasts all summer long.
At Longfield Gardens, we take pride in providing high-quality tubers that are ready to perform in your yard. We ship our begonias at the ideal time for your region, taking the guesswork out of the process. Remember that gardening is a journey that rewards patience and observation. Watch your local weather, feel the soil, and when the warmth finally arrives, you’ll be ready to create the beautiful, shaded retreat you’ve been dreaming of.
Final Thought Successful begonia gardening is less about following a strict calendar and more about following the warmth. Once the nights are mild and the soil is cozy, your begonias will take off and reward you with months of spectacular color.
FAQ
Can I plant begonias outdoors if it is still raining a lot in the spring?
It is best to wait until the soil is no longer "mucky" or waterlogged. Begonia tubers are sensitive to excessive moisture before they have established roots, and planting them in very wet, cold soil can lead to rot. Wait for a break in the rain and for the soil to become crumbly rather than sticky.
What happens if a surprise frost occurs after I have planted my begonias?
If a late frost is predicted, you should protect your begonias. For plants in containers, the easiest solution is to move them into a garage or shed overnight. For plants in the ground, cover them with a frost blanket, an old sheet, or even an upside-down bucket to trap the heat from the soil and shield the leaves from the cold.
Is it better to plant begonias in the sun or the shade?
Most begonias prefer partial shade or filtered sunlight. While they can handle some morning sun, the intense heat of the afternoon can scorch their leaves and cause flowers to wilt. A location that receives "dappled" light under a tree or on a porch that faces east is usually the best environment for healthy growth. This sun and shade guide for begonias offers more detail.
Why are the leaves on my newly planted begonias turning brown at the edges?
This is often a sign of transplant shock or "leaf scorch." If the plants were moved from a dark store or an indoor setting directly into bright sun, the leaves can burn. It can also happen if the air is very dry or if the plant is catching too much wind. Ensure they have adequate shade and are protected from strong breezes as they get established.
