When Should I Plant Begonias for the Best Blooms?

Table of Contents

1. Introduction
2. Understanding Your Begonia Type
3. The Role of Frost Dates and Temperature
4. When to Start Begonias Indoors
5. When to Move Begonias Outdoors
6. Planting Directly in the Garden
7. Regional Timing Guidelines
8. Choosing the Right Spot at the Right Time
9. Managing Expectations: The Growth Timeline
10. Caring for Your Timely Planting
11. Wrapping Up the Season
12. Conclusion
13. FAQ

Introduction

There is a special kind of magic in watching a shady corner of the yard transform into a lush, tropical retreat. For many of us, begonias are the secret to that transformation. These plants are famous for their brilliant colors and interesting leaf patterns, offering a dependable way to brighten up porches, patios, and garden beds that do not get much direct sun. At Longfield Gardens, we love how begonias provide a steady stream of flowers from early summer all the way until the first frost.

Deciding when to plant begonias is the most important step in ensuring your garden thrives. Because these plants are native to tropical climates, they have specific needs when it comes to warmth and timing. If you get the timing right, you are rewarded with vigorous growth and a spectacular floral show. This guide is designed to help you understand exactly when to start your begonias, whether you are starting tubers indoors or planting nursery-grown starts directly into your landscape.

We will cover the ideal temperatures for planting, how to coordinate with your local frost dates, and why a little bit of patience goes a long way with these heat-loving beauties. Whether you are a beginner or a seasoned gardener, the following steps will help you time your planting perfectly for a successful growing season.

Success with begonias comes down to matching their tropical nature with your local weather patterns.

Understanding Your Begonia Type

Before we can answer exactly when to plant, it is helpful to know which type of begonia you are growing. While their care is similar, their starting points can differ. The most common varieties you will find for home gardens fall into a few specific categories.

Tuberous Begonias

These upright double begonias are a favorite at Longfield Gardens because of their large, rose-like blooms and dramatic colors. They grow from a fleshy, bulb-like structure called a tuber. Tuberous begonias are often started indoors quite early in the spring to give them a head start on the blooming season. They are perfect for hanging baskets and containers.

Wax Begonias (Fibrous-Rooted)

You likely recognize these from garden centers. They have smaller, succulent-like leaves and clusters of tiny red, white, or pink flowers. They are usually grown as annuals and have fibrous roots rather than tubers. Because they are often sold as established plants in "six-packs," the timing for putting them in the ground is slightly different than starting tubers from scratch.

Rex and Rhizomatous Begonias

These varieties are primarily grown for their stunning, multi-colored foliage. They grow from rhizomes, which are thick stems that creep along the soil surface. While often kept as houseplants, they can spend the summer outdoors once the weather is warm enough.

Cane-Like Begonias

Commonly known as "Angel Wing" begonias, these have upright, bamboo-like stems. They are incredibly durable and can grow quite large. Like the Rex varieties, they are very sensitive to the cold and should only move outside when the summer heat has truly arrived.

Key Takeaway Most garden begonias are tropical perennials grown as annuals in the United States. No matter the type, they all share one common requirement: they must have warm weather to thrive.

The Role of Frost Dates and Temperature

The most important rule for planting begonias is to wait until the danger of frost has completely passed. Begonias have no tolerance for freezing temperatures. Even a light, overnight frost can damage the tender leaves or cause the entire plant to collapse.

Finding Your Last Frost Date

In the United States, your "last frost date" is the average date in spring when the final freeze occurs in your area. This date varies significantly depending on your USDA hardiness zone. For example, gardeners in Georgia may reach this date in March, while those in Minnesota may have to wait until late May or early June. You can find this date by checking with a local university extension office or using the USDA hardiness zone map.

Soil Temperature Matters

Air temperature is only half of the story. Begonias also need warm soil to begin growing. If you tuck a begonia tuber into cold, damp soil in early spring, it may sit dormant or, worse, begin to rot. We recommend waiting until the soil temperature consistently reaches at least 60°F.

A simple way to test this without a thermometer is to observe other plants. If the grass is growing vigorously and your local trees are fully leafed out, the soil is likely warming up. Another good indicator is the behavior of other "warm-season" vegetables like tomatoes or peppers. If it is safe to plant those, it is usually safe for your begonias.

Nighttime Lows

Begonias prefer nighttime temperatures to stay consistently above 50°F, and ideally closer to 60°F. If your daytime temperatures are warm but the nights are still dipping into the 40s, it is best to keep your plants protected. Cold nights can stunt the growth of young begonias, leading to a much slower start to the blooming season.

When to Start Begonias Indoors

One of the best ways to get the most out of your begonias is to start them indoors before the weather warms up. This is especially true for tuberous begonias. Because they can take several weeks to sprout and even longer to reach blooming size, a head start inside your home gives you flowers much earlier in the summer.

The 8 to 12 Week Rule

We recommend starting your begonia tubers indoors about 8 to 12 weeks before your area’s last expected frost date. This window gives the tubers enough time to develop a strong root system and several inches of top growth. For a step-by-step refresher, see How to Start Tuberous Begonias Indoors.

For example, if your last frost date is May 15, you should aim to plant your tubers in pots indoors sometime between mid-February and mid-March. If you wait until May to plant the tubers directly into the garden, you may not see significant blooms until late August. Starting early ensures a full season of color.

How to Start Tubers

To start your tubers, follow these simple steps:

• Fill a shallow tray or small individual pots with a high-quality, well-draining potting mix.
• Place the tuber with the indented (hollow) side facing up. This is where the sprouts will emerge.
• Cover the tuber with just a thin layer of soil—about half an inch to an inch is usually plenty.
• Water the soil lightly to settle it, but do not soak it.
• Place the containers in a warm spot with bright, indirect light. A temperature of 65°F to 75°F is ideal for encouraging sprouts.

Patience During Sprouting

Do not be discouraged if you do not see green growth immediately. Begonia tubers are famous for taking their time. It can take anywhere from two to four weeks for the first tiny pink or green nubs to appear on the surface of the tuber. Once they start, however, the growth will accelerate quickly.

Key Takeaway Starting begonias indoors is an easy win for gardeners in northern climates. It turns a short blooming season into a long one by bypassing the chilly spring weeks.

When to Move Begonias Outdoors

The transition from the cozy indoors to the unpredictable outdoor garden is a big moment for a plant. Knowing when to make this move is the key to preventing "transplant shock," which can cause leaves to drop or growth to stall.

The "Settle-In" Period

Wait until the weather has truly settled. In many parts of the country, spring can be a rollercoaster of warm afternoons and surprisingly cold nights. We suggest waiting at least one to two weeks after your last frost date has passed before moving your begonias outside for good. This ensures that the weather is stable and the soil has had plenty of time to absorb the sun's heat.

Hardening Off Your Plants

If you have grown your begonias indoors, you cannot move them directly into the garden all at once. They need a transition period called hardening off. This process helps the plant adjust to the wind, direct light, and temperature fluctuations of the outdoors.

1. Start slow: On a warm, calm day, set your pots outside in a sheltered, shady spot for about two hours.
2. Increase time: Each day, leave them out for an extra hour or two.
3. Introduce light: Gradually move them into areas with a little more light (though remember that most begonias still prefer shade).
4. Stay overnight: After about a week of daytime outings, if the nights are staying above 55°F, you can leave them out overnight.
5. Final planting: Once they have spent several full days and nights outside without showing signs of stress, they are ready to be planted in their permanent garden beds or containers.

Signs the Weather is Right

If you see your neighbors planting zinnias, coleus, or impatiens, it is likely the right time for your begonias. These "warm-weather annuals" all share similar temperature requirements. If the air feels comfortable for you to sit outside in a light t-shirt in the evening, your begonias will likely be happy too.

Planting Directly in the Garden

If you prefer not to start your plants indoors, you can plant begonia tubers or nursery starts directly into the ground. The timing for this is much stricter because the outdoor environment is less controlled.

Direct Sowing Tubers

In warmer climates (Zones 9 through 11), you can often plant tubers directly into the garden as soon as the soil is warm in the spring. For the rest of the country, wait until the soil is at least 60°F. For a ready-made bulk option, Begonia Non Stop Mix - Bulk Offer is a convenient choice.

When planting directly in the garden:

• Check the drainage: Make sure the spot you choose doesn't hold standing water after a rain. Begonias love moisture but will struggle in "wet feet."
• Depth is key: Plant tubers about 1 inch deep and space them 8 to 12 inches apart to allow for airflow.
• Watch the calendar: In the Mid-Atlantic and Midwest, this is usually late May or early June. In the South, this could be as early as April.

Planting Nursery Starts

If you buy begonias that are already in bloom from a garden center, they are ready to go into the ground as soon as you get home—provided the frost risk is gone. Because these plants have been grown in a greenhouse, they might be even more sensitive to a sudden cold snap than plants you grew yourself. If a surprise cold night is predicted after you have planted them, simply cover them with a light cloth or an inverted bucket for the night.

Regional Timing Guidelines

Because the United States is so large, "spring" happens at different times for everyone. Here is a general look at when you might consider planting based on your region.

The Southern United States

In warmer regions like Florida, the Gulf Coast, and parts of the Southwest, you can often plant begonias as early as March or April. In the hottest parts of the South, the "when" is more about avoiding the most intense mid-summer heat. For these areas, getting plants established early in the spring helps them build a strong root system before the humidity and temperatures soar.

The Central and Mid-Atlantic United States

For the middle of the country, May is the magic month. While early May can sometimes bring a rogue frost, by the middle or end of the month, the soil and air are usually perfect for begonias. For Longfield Gardens' Shipping Information, the schedule is based on your USDA plant hardiness zone.

The Northern United States and High Elevations

In places like New England, the Upper Midwest, or the Pacific Northwest, you may need to wait until the very end of May or even the first week of June. Short growing seasons in these areas make the 8-week indoor head start almost essential if you want to enjoy a long period of flowers.

What to do next

• Identify your USDA hardiness zone.
• Mark your average last frost date on the calendar.
• Count back 8 to 12 weeks from that date to find your indoor starting window.
• Monitor soil temperatures in the spring before moving plants outside.

Choosing the Right Spot at the Right Time

Timing your planting is also about matching the plant to the right location at that specific time of year. As the sun’s angle changes from spring to summer, a spot that was shady in April might be in full sun by July.

Light Requirements

When you plant in late spring, look for areas with "filtered light." This means the light that peeks through the leaves of a tall tree. Most begonias thrive in partial shade. While some wax begonias can handle more sun, the large-flowered tuberous types can actually have their leaves scorched by intense afternoon sunlight. For a deeper look at how exposure changes through the season, see How Sunlight Affects Plants.

Wind Protection

When you are deciding when to plant, also consider the wind. Late spring can often bring heavy thunderstorms or breezy days. If you are planting tall varieties or placing hanging baskets, make sure they are in a spot protected from strong gusts. Begonia Upright Double Bertini is a strong container-friendly option.

Managing Expectations: The Growth Timeline

Once you have your begonias in the ground or in their outdoor pots at the right time, what should you expect to see? Understanding the natural rhythm of the plant helps you enjoy the process without worry.

The First Month

During the first few weeks after planting, most of the action is happening underground. The plant is focusing its energy on establishing roots in its new home. You might not see a lot of new leaves right away, and that is perfectly normal. As long as the plant looks turgid (firm) and green, it is doing its job.

The Mid-Summer "Pop"

Once the heat of July arrives, begonias really start to take off. This is when the growth becomes very noticeable. If you want the classic rose-like look, Begonia Upright Double Roseform Pink is a standout. You will see more branching and the first flower buds will begin to swell.

The Long Harvest of Color

Unlike many perennials that bloom for only two or three weeks, begonias are marathon runners. Once they start blooming, they will continue to produce new flowers as long as they are happy. For a fuller display, Begonia Upright Double Superba Mix - Bulk Offer is an easy bulk choice. We find that the best displays often happen in late August and September when the nights start to cool down just a little bit, but the soil is still nice and warm.

Caring for Your Timely Planting

Proper timing sets the stage, but a little bit of ongoing care keeps the show running. Now that you have planted at the right time, you want to maintain that momentum.

Watering Correctly

Begonias prefer to be "consistently moist" but not soggy. The best way to achieve this is to check the soil with your finger. If the top inch feels dry, it is time to water. In the heat of summer, containers may need water every day, while garden beds might only need it a few times a week. For more ideas on summer bulb containers, see How to Grow Summer Bulbs in Containers. Always try to water the soil directly rather than the leaves to keep the foliage healthy.

Feeding Your Plants

Because begonias bloom so prolifically, they are "heavy feeders." They use a lot of energy to create those flowers. Once your plants are established and growing well—usually about a month after planting—you can begin using a balanced, water-soluble fertilizer. Following the instructions on the label every few weeks will ensure the plant has the nutrients it needs to keep producing flowers until autumn.

Maintenance

Many modern begonias are "self-cleaning," meaning the old flowers fall off on their own. However, if you see spent blooms or yellowing leaves, feel free to snip them off. This keeps the plant looking tidy and helps prevent any mold or fungus from moving in on old tissue.

Wrapping Up the Season

As the summer winds down, the "when" shifts from planting to protecting. Just as you waited for the frost to leave in the spring, you must watch for its return in the fall.

End of Season Care

When the first light frost hits, the foliage of your begonias will likely turn black. This is the signal that the growing season is over. If you live in a cold climate and want to save your tubers for next year, this is the time to dig them up. If you want a refresher on saving tubers for next year, see How to Overwinter Begonia Plants.

Simply cut the stems back to a few inches, lift the tubers from the soil, and let them dry in a cool, frost-free place like a garage or basement. Once they are dry, you can store them in peat moss or paper bags until it is time to start the cycle all over again next spring.

Conclusion

Planting begonias is one of the most rewarding ways to bring life and color to the shaded parts of your landscape. By respecting their tropical origins and waiting for the right combination of warm air and soil, you set your garden up for success. Whether you give your tubers an 8-week head start indoors or wait for the gentle warmth of late May to plant outdoors, the result is a stunning display that lasts all summer long.

At Longfield Gardens, we believe that gardening should be a source of joy, not stress. If you follow the simple rules of waiting for the frost to pass and letting the soil warm up, your begonias will do the rest of the work.

• Start tubers indoors 8-12 weeks before the last frost for early blooms.
• Wait for soil to reach 60°F before planting outside.
• Ensure nights are consistently above 50°F to 55°F.
• Harden off indoor plants for a week to prevent shock.

"The secret to beautiful begonias isn't a complex trick; it is simply matching the plant's need for warmth with the natural rhythm of the seasons."

Now is the perfect time to check your local frost dates and start planning your most colorful shade garden yet. We look forward to helping you grow a more beautiful yard with our high-quality begonia tubers.

FAQ

Can I plant begonias in the ground if it is still cold at night?

It is best to wait until nighttime temperatures are consistently above 50°F. While begonias can survive a single chilly night, prolonged cold will stunt their growth and can lead to root rot if the soil is also wet. If you have already planted and a cold snap is predicted, cover your plants with a cloth for protection.

How do I know if the soil is warm enough to plant my begonias?

A good rule of thumb is to wait until you are comfortable planting other warm-season plants like tomatoes or basil. If you want to be precise, use a soil thermometer to ensure the ground has reached at least 60°F. Planting in cold soil often leads to the tubers sitting dormant rather than growing.

What happens if I plant my begonias too early?

If begonias are planted too early and encounter a frost, the tender leaves and stems will likely turn black and die. Even without a frost, cold soil and air can cause the plants to become stressed, making them more susceptible to pests and diseases. Waiting for the right weather ensures the plants grow vigorously from the start.

Is it too late to plant begonias in June?

It is not too late! While starting earlier gives you a longer blooming season, begonias planted in June will grow very quickly because the soil is already warm. You will still enjoy several months of beautiful flowers throughout the summer and well into the autumn until the first frost arrives.