Advice for how to grow begonias from seed is simple: get started early. While prime seed-starting time is still weeks away for most parts of North America, there’s one plant that requires a bit more time to grow. Begonias are beautiful annuals that are both shade-loving and deer-resistant and they make a beautiful addition to almost any landscape. If you want to grow some of your own, you might be surprised to learn that, unlike most other annual flowers, mid to late January is the perfect time to start begonias from seed.
Starting begonia seeds indoors requires some advance planning and care to ensure success, but the results are well worth the extra effort. With proper timing and techniques, you can grow transplants ready to bring striking colors and varieties to your garden beds, containers and hanging baskets.
Why Start Begonias From Seed?
While you can certainly buy started begonia plants there are some key advantages to growing your own from seed
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Wider selection – Nurseries typically offer just a few popular varieties but you can choose from dozens of types by starting from seed.
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Cost savings – A packet of seeds costs just a few dollars and can produce hundreds of plants.
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Fun to grow – It’s enjoyable to nurture seeds into mature, blooming plants.
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Stronger plants – Those grown from seed develop stronger root systems than cuttings.
So if you want unique begonias or to grow them affordably in quantity, starting from seed is the way to go.
When Should You Plant Begonia Seeds?
The timing of sowing begonia seeds depends on whether you are growing tuberous or fibrous rooted types:
Fibrous Rooted Begonias
For varieties like wax, cane, angel wing, dragon wing and semperflorens, start seeds indoors 10-12 weeks before your last expected spring frost date.
This gives enough time for seeds to germinate and seedlings to mature into sturdy transplants that can move outside after frost danger has passed.
Tuberous Begonias
For tuberous types, start earlier at 14-16 weeks before your planned outdoor planting date.
Tuberous begonia seeds need extra time to produce tubers that will bloom abundantly in the garden.
So mid-January to March is the perfect window for starting begonias indoors in most climates.
How to Grow Begonias Successfully From Seed
Follow these steps for the best results starting begonia seeds inside:
Get High Quality Seeds
Purchase fresh seeds from reputable suppliers for optimal germination rates. Look for popular types like wax begonia, rex begonia, semperflorens and tuberous begonia seeds.
Use Proper Seed Starting Mix
Fill containers with a sterile, lightweight seed starting mix. This provides drainage and nutrients begonia seeds need.
Give Warmth for Germination
Begonias require consistent warmth between 70-75°F (21-24°C) to sprout well. Use a heat mat or other method to maintain this temperature.
Sow Seeds Correctly
Plant seeds just below the mix surface since begonias need light to germinate. Gently water to avoid dislodging small seeds. Bottom watering works well.
Provide Bright Indirect Light
Place seedlings under grow lights or near a sunny window covered with sheer curtains. Avoid direct hot sunlight.
Maintain High Humidity
Cover seed containers with plastic domes or plastic wrap. This keeps ideal high humidity levels.
Transplant and Harden Off
Transplant into pots once seedlings have 2-3 sets of true leaves. Gradually expose to outdoor conditions over 7-10 days before planting in garden after frost danger has passed.
Tips for Growing Success
Follow these tips to overcome common challenges and get great results starting begonias from seed:
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Provide consistent moisture and temperatures. Fluctuations cause poor germination.
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Use sterile tools and containers to prevent fungal disease.
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Thin overly crowded seedlings to prevent problems.
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Fertilize lightly every 2-3 weeks once true leaves develop.
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Handle new seedlings carefully by their leaves when transplanting to avoid damage.
Enjoy Beautiful Begonias From Seeds
With the right timing and care, growing begonias from seeds indoors is very rewarding. In 10-16 weeks, you can have lovely transplants ready to enhance your garden with diverse colors and forms. Start planning now when you should sow your begonia seeds indoors this season for stunning results.
Why Start Begonias From Seed
Annual flowers are definitely not the most expensive plants at your local greenhouse, but if you grow (or sell) a lot of them, starting your own from seed can save you a ton of money. While starting marigolds, cosmos and salvias from seed is as simple as can be, when you start begonias from seed, it requires a bit more time and effort.
As with many other plants, starting begonias from seed, rather than buying transplants from a grower, means you’ll have a better varietal selection to choose from and you’ll get a lot more bang for your buck. Most commercial growers focus on growing just three or four popular types of begonias, but there are dozens of selections you can choose from when growing begonias from seed.
How to Grow Begonias From Seed: Four Steps
Begonia seeds are extremely tiny. In fact, each seed isn’t much bigger than a speck of dust. Handling these miniscule seeds can be difficult, though you can purchase pelleted seeds to make the job a bit easier. Add that to the fact that begonias take a very long time to germinate, and that’s probably why most folks shy away from starting them from seed. However, once you get the hang of starting begonias from seed, you’ll discover your efforts are well worth it.
Use new seedling trays or flats to plant begonias from seed. The plants are prone to developing fungal diseases, including damping off and botrytis, so new or disinfected seed trays are a must. You’ll also need new sterile potting soil that’s formulated specifically for seed starting.
Once your seed trays are filled with sterile potting mix, it’s time to plant your begonia seeds. Begonias need light to germinate, so simply broadcast the seeds across the surface of the potting mix and press them against the surface of the soil with your fingertips or a flat piece of cardboard. Do not cover the seeds. Try to distribute them evenly across the soil, but it’s okay to have them spaced fairly closely. Begonias always need to be transplanted when they’re young, so if the seedlings end up too close, it’s no big deal; you’ll be separating them later anyway.
When I start begonias from seed, I water the newly planted seeds in with a mister, rather than a hose nozzle, to make sure they stay in place and don’t float away.
Cover the seeding tray with a sheet of clear plastic or a humidity dome, and place the tray under grow lights that run for about 14-18 hours per day and stand about 2-3″ above the tops of the trays. Put heat mats under the trays to improve and speed germination. Some varieties of begonias can take weeks, if not months, to germinate, so don’t give up on them even if it seems to be taking forever. Make sure the seed flats don’t dry out; water them with a mister or spray bottle whenever necessary. Remove the plastic or humidity dome as soon as the seeds start to germinate. Raise the lights as the plants grow.
How To Start Begonias From Seed || Starting Begonia Seeds
FAQ
Are begonias hard to start from seed?
Germination is fairly easy (if the seeds are viable). The difficult part is moving them up to their next pot if you sowed a bunch of seed. Just keep them in a moist environment until they are big enough to grow on their own.
When to start begonias inside?
Starting Begonias Indoors
In late February or early March, plant the tubers (concave side up) just below the soil level. Soil should be somewhat moist.
How long do begonia seeds take to sprout?
Sowing Seed Indoors:
Sow very shallowly in seed starting formula as seeds need light to germinate well. Keep the soil moist at 70-75 degrees. Begonias can benefit with bottom heat. Seedlings emerge in 15-21 days.