What Month Do You Plant Begonias?

Table of Contents

1. Introduction
2. The Short Answer: What Month Do You Plant Begonias?
3. Why Timing Matters for Begonias
4. Starting Begonias Indoors: The February to April Window
5. Planting Begonias Outdoors: The May to June Window
6. Understanding Different Types of Begonias
7. Regional Planting Guide for the United States
8. How to Plant Begonia Tubers: A Simple Guide
9. Watering and Fertilizing After Planting
10. Safety Note for Pet Owners
11. Troubleshooting Common Timing Issues
12. Caring for Begonias After the Season Ends
13. Conclusion
14. FAQ

Introduction

Finding the perfect plant for a shady corner is one of the most rewarding moments for any gardener. Begonias are the champions of these quiet, cool spaces, offering lush foliage and brilliant colors that last from early summer right through the first frost. At Longfield Gardens, we love how these versatile plants transform porches, patios, and garden beds into vibrant retreats with very little effort.

Whether you are looking for the rose-like blooms of tuberous begonias or the waxy leaves of bedding varieties, timing is everything. This guide will help you determine the exact right month to get your begonias in the ground or in pots. We will cover how to start them indoors for an early head start and when it is safe to move them into your outdoor garden.

Getting the timing right ensures your plants have the warmth they need to thrive without the risk of a late spring chill. By following a few simple rules about soil temperature and frost dates, you can enjoy a season full of spectacular, non-stop blooms.

The Short Answer: What Month Do You Plant Begonias?

The best month to plant begonia tubers depends entirely on your local climate and whether you are starting them indoors or directly outside. For most gardeners in the United States, the window for planting falls between February and June.

If you are starting begonia tubers indoors to get a head start on the season, the best months are February, March, or April. Starting them early inside allows the plants to develop strong roots and stems so they are ready to bloom as soon as the weather warms up.

If you prefer to plant your begonias directly into the garden or outdoor containers, the best months are May or June. Begonias are tropical plants that absolutely require warm soil and a total absence of frost. In most regions, wait until late spring when the danger of a freeze has completely passed and the soil feels warm to the touch.

Key Takeaway: Start begonia tubers indoors in late winter (February–March) for early summer flowers, or wait until late spring (May–June) to plant them directly outdoors once the weather is consistently warm.

Why Timing Matters for Begonias

Begonias are native to tropical and subtropical regions. This means they have no natural defense against freezing temperatures. Even a light frost can damage the tender stems and leaves, and a hard freeze will usually kill the plant entirely.

Timing your planting correctly is not just about avoiding death; it is about encouraging growth. Begonias will often sit idle in cold, damp soil. They simply "sleep" until the environment matches their tropical origins. By waiting for the right month, you ensure the plant hits the ground running rather than struggling to survive a chilly spring.

The 60-Degree Rule

The most important number for a begonia gardener is 60°F (15°C). This is the ideal minimum soil temperature for planting begonias outdoors. While many other spring flowers, like pansies or snapdragons, can handle a bit of a chill, begonias prefer "settled" weather. This means the nights are no longer dipping into the 40s and the soil has been warmed by several weeks of spring sunshine.

Soil Temperature vs. Air Temperature

It is a common mistake to plant begonias as soon as the first warm day arrives in April. However, soil temperatures lag behind air temperatures. While the afternoon sun might feel like summer, the earth a few inches down may still be cold and wet from winter snow or rain. Planting in cold, wet soil is a leading cause of tuber rot. Waiting until May or June ensures the "engine" of the plant—the roots and tuber—stays healthy and active.

Starting Begonias Indoors: The February to April Window

Many gardeners choose to start their tuberous begonias indoors. This is an excellent strategy if you live in a northern climate with a short growing season. By starting in February or March, you effectively add two months to your blooming window.

Why Start Early?

Tuberous begonias are somewhat slow to wake up. It can take anywhere from four to eight weeks for a tuber to sprout and produce its first set of true leaves. If you wait until June to plant a dormant tuber in the garden, you might not see flowers until late August. Starting indoors ensures you have a leafy, budding plant ready to go outside the moment the weather permits.

How to Start Indoors

1. Select Your Containers: Use shallow pots or a seed tray with plenty of drainage holes.
2. Use High-Quality Mix: Fill the containers with a light, well-draining potting soil.
3. Position the Tubers: Place the tuber with the indented (hollow) side facing up. This "bowl" shape is where the stems will emerge.
4. The Light Touch: Cover the tuber with just a half-inch to one inch of soil. Do not bury them too deeply.
5. Warmth and Light: Keep the pots in a warm spot (about 70°F) with bright, indirect light. A windowsill that doesn't get harsh, direct midday sun is often perfect.
6. Water Sparingly: This is the most critical step. Water once to settle the soil, then wait until you see green sprouts before watering again. Overwatering a dormant tuber is the quickest way to cause rot.

What to Do Next:

• Check your local "average last frost date" online.
• Count back 8 weeks from that date.
• Mark that week on your calendar as your "Indoor Start Date."
• Ensure you have fresh potting mix and clean containers ready for February or March.

Planting Begonias Outdoors: The May to June Window

Once the trees are fully leafed out and you are consistently wearing short sleeves outside, it is usually time to plant begonias in the garden. For most of the country, this is late May or early June.

Watching the Weather

Instead of following a strict date on the calendar, we recommend watching your local weather forecast. Look for a stretch of time where the nighttime temperatures are reliably staying above 50°F. If the forecast still shows nights in the low 40s, it is better to keep your begonias in their pots on a protected porch or inside a little longer.

Hardening Off

If you started your plants indoors, you cannot move them directly from a cozy living room to the garden all at once. They need a transition period called "hardening off."

• Day 1-3: Place the plants outside in a sheltered, shady spot for two or three hours during the warmest part of the day, then bring them back inside.
• Day 4-7: Increase the time outdoors by a few hours each day, gradually exposing them to a bit more light (but never direct, hot sun).
• Day 8+: If the nights are warm, you can leave them out overnight. After a full week of this, they are ready to be planted in their permanent homes.

Choosing the Best Spot

Begonias are famous for their love of shade gardens.

• Light: Filtered light under high trees or the dappled shade of a pergola is ideal. A spot that gets four hours of gentle morning sun and afternoon shade is perfect. Avoid south-facing walls that trap and radiate heat.
• Soil: They need "rich and crumbly" soil. If your garden soil is heavy clay, we suggest adding some compost or planting in containers instead. Drainage is vital; begonias like to be moist but never "sit in a puddle."

Understanding Different Types of Begonias

While "when to plant" is generally consistent across the family, there are slight nuances depending on the specific type of begonia you choose.

Tuberous Begonias

These are the stars of the show, known for their massive, rose-like flowers. We provide high-quality 5/6 cm begonia tubers that produce large, bushy plants. Because these grow from a fleshy tuber, they are the most sensitive to cold, wet soil. These are the ones you most likely want to start indoors in March.

Wax Begonias (Fibrous-Rooted)

These are often sold in "flats" or cell packs at garden centers. They have smaller, succulent-like leaves and many tiny flowers. They are a bit tougher than tuberous begonias but still need warm weather. Since they are already grown when you buy them, you can usually plant them as soon as the frost risk is gone in May.

Rex Begonias

Grown primarily for their stunning, colorful foliage, Rex begonias are often kept as houseplants. If you want to move them to a shady patio for the summer, wait until June when the humidity is higher and the air is truly warm. They dislike cold drafts and will show their displeasure by dropping leaves if moved outside too early.

Hardy Begonias (Begonia grandis)

This is the rare exception to the "tender" rule. Hardy begonias can survive the winter in USDA zones 6 through 9. They emerge much later in the spring than other perennials—often not until May. If you have these in your garden, don't worry if you don't see them in April; they are simply waiting for the soil to warm up.

Regional Planting Guide for the United States

Because the US covers so many different climates, "the month of May" means something very different in Florida than it does in Maine. Here is a general breakdown of when to plant based on your region.

The South and Southwest (Zones 8-11)

In these warm climates, you can often plant begonias as early as March. However, the challenge in these regions is not the cold, but the heat. In places like Florida or Texas, begonias should be planted early enough to establish themselves before the intense heat of July. In these zones, deep shade is a requirement rather than a suggestion.

The Mid-Atlantic and Midwest (Zones 6-7)

The sweet spot for these regions is usually mid-to-late May. This is when the soil has finally shed the winter chill. If you have a particularly rainy spring, wait an extra week to ensure the soil isn't saturated, which can lead to tuber rot.

The North and High Elevations (Zones 3-5)

In northern states or mountain regions, frost can linger well into May. In these areas, early June is often the safest and most productive month to plant begonias outdoors. Because the summer season is shorter here, starting your tubers indoors in March is highly recommended so you don't miss out on weeks of color.

"A common gardening win is waiting just one extra week. If you aren't sure if it's warm enough for begonias, wait. They grow so fast in warm weather that they will quickly catch up to plants put out too early."

How to Plant Begonia Tubers: A Simple Guide

When the right month arrives, the actual planting process is straightforward. We believe in keeping things simple to ensure the best results.

In Containers

Most people find begonias easiest to manage in pots. This allows you to move the plant if it’s getting too much sun or to bring it inside if a surprise late frost is forecasted.

• Potting Mix: Use a fresh, peat-based potting soil.
• Spacing: If you are using a standard 12-inch pot, plant two to three tubers. They like to be a little cozy.
• Depth: Tuck the tuber in so it is covered by about an inch of soil. Ensure the "bowl" side is up.
• Watering: Water once thoroughly after planting. Then, be patient. Do not water again until you see the first green leaf breaking the surface.

In the Ground

If you are planting in a garden bed, space the tubers about 10 to 12 inches apart. This gives the plants plenty of room for air to circulate, which helps prevent mildew on the leaves.

• Amend the Soil: Mix in a little compost to help with drainage and provide slow-release nutrients.
• Mulch: A light layer of mulch can help keep the soil moisture consistent, but keep the mulch an inch or two away from the main stem of the begonia to prevent rot.

Watering and Fertilizing After Planting

Once your begonias are planted in the correct month and starting to grow, they need consistent care to keep those blooms coming.

The "Deep Soak" Method

Begonias have relatively shallow root systems. They don't like to dry out completely, but they also hate being soggy. We recommend checking the soil with your finger. If the top inch feels dry, it is time to water. When you water, give the plant a deep soak so the moisture reaches the bottom of the root ball, then let it dry out a bit before the next round.

Feeding for Flowers

To keep begonias blooming from July through October, they need "fuel."

• Early Season: When the plant is just growing leaves, a balanced fertilizer is fine.
• Bloom Season: Once you see the first flower buds, switch to a fertilizer higher in phosphorus (the middle number on the package). This encourages more flowers rather than just more green leaves.
• Frequency: Most gardeners find success fertilizing every two weeks at half-strength.

Safety Note for Pet Owners

It is important to note that begonias can be toxic if ingested by pets, particularly the tubers. If you have curious dogs or cats that like to dig or chew, consider planting your begonias in hanging baskets or on high plant stands where they are out of reach. Always monitor your pets around new garden additions.

Troubleshooting Common Timing Issues

Sometimes, despite our best efforts, the weather doesn't cooperate. Here is how to handle common timing challenges.

What if I planted too early and a frost is coming?

Don't panic! If your begonias are in pots, simply move them into a garage or mudroom for the night. If they are in the ground, cover them with a frost blanket, an old bedsheet, or even a large plastic bucket turned upside down. Remove the cover as soon as the sun comes up and the temperature rises above freezing.

Why aren't my tubers sprouting?

If you planted in March and it is now April with no green in sight, the most likely culprit is temperature. If the room or the soil is below 60°F, the tuber will stay dormant. Try moving the pot to a warmer location, like the top of a refrigerator. As long as the tuber feels firm like a potato and isn't soft or mushy, it is still healthy—it’s just waiting for a bit more warmth.

My begonia is "leggy" and tall.

This usually happens when a plant is started indoors too early or isn't getting enough light. If the stems are very long and falling over, you can gently stake them with a small bamboo skewer. Next year, wait a few weeks longer to start them, or move them to a brighter window.

Caring for Begonias After the Season Ends

Because begonias are tender perennials, they don't have to be a one-year investment. You can save the tubers and replant them next spring.

The End-of-Season Transition

As the days get shorter in September and October, your begonias will naturally start to slow down. When the first light frost hits and blackens the foliage, it is time to act.

1. Lift the Tubers: Carefully dig the tubers out of the ground or remove them from their pots.
2. Clean Them Up: Cut the stems back to about an inch above the tuber. Gently brush off the loose soil, but don't worry about getting them perfectly clean.
3. Cure Them: Lay the tubers in a dry, shady spot for a few days to let the outer "skin" toughen up.
4. Winter Storage: Place them in a box with some peat moss, sawdust, or even wrapped in newspaper. Store them in a cool, dark, dry place (like a basement) where the temperature stays around 50°F.

By following this cycle, you can enjoy the same beautiful begonias year after year, simply restarting the process every February or March.

Conclusion

The secret to beautiful begonias isn't a "green thumb"—it is simply understanding their love for warmth and shade. By choosing the right month to plant, you give these tropical beauties the best possible start. Remember to start your tubers indoors during February or March if you want an early show, or wait for the settled warmth of May and June to plant directly in the garden.

At Longfield Gardens, we want every gardener to feel the success of a blooming shade garden. Begonias offer a high reward for very little work, provided you respect the thermometer. If you provide them with warm soil, dappled light, and consistent moisture, they will reward you with spectacular color all season long.

Final Tips for Success:

• Always check that the indented side of the tuber is facing up.
• Wait for 60°F soil before planting outdoors.
• Fertilize every two weeks once blooms appear.
• Save your tubers in the fall to enjoy them again next year.

The next step is easy: check your hardiness zone, look up your frost date, and get ready for a beautiful season. We stand behind the quality of our tubers and are here to help you grow a garden you love.

FAQ

What is the earliest month I can start begonias?

You can start begonia tubers as early as February or March. Starting them inside about 8 to 12 weeks before your last frost date gives them enough time to develop stems and leaves so they are ready to bloom shortly after being moved outside.

Can I plant begonia tubers directly in the ground in April?

In most parts of the US, April is too early to plant begonias outdoors. The soil is usually still too cold and the risk of a surprise frost is too high. It is better to wait until May or June when the soil temperature is consistently at least 60°F.

How do I know when it is safe to move my begonias outside?

Wait until the nighttime temperatures are reliably above 50°F and there is no longer any threat of frost in your local forecast. It is also important to "harden off" your plants by gradually introducing them to the outdoor air for a week before planting them permanently.

What month do begonias start blooming?

If you start your tubers indoors in March, you can expect to see the first flowers in June or July. If you plant dormant tubers directly in the garden in June, they may not begin blooming until late July or August. Once they start, they will bloom continuously until the first frost of autumn.