How to Grow Begonias in a Greenhouse: A Step-By-Step Guide for Seed to Harvest

While Begonias are commonly sold as annual plants in cold climates, they are actually tropical perennials that can live for many years. In a greenhouse, many types of flowering Begonias will bloom year-round with proper care. Nevertheless, some rhizomatous varieties don’t flower at all, but they have amazing foliage. Begonia varieties are virtually endless. A Begonia can be found in countless colors, sizes, and shapes, with over 1,000 species and many more varieties and hybrids. There are four main types: fibrous, tuberous, canes, and rhizomatous.

Tuberous: These Begonias have bulbs (tubers) and large flowers
Rhizomatous: These Begonias are mostly grown for their gorgeous foliage
Cane: These Begonias are usually large, showy, and constant bloomers
Fibrous: These Begonias are common bedding plants famous for their prolific flowers

How to Grow Begonias in a Greenhouse

Soil Requirements for Growing Begonias in the Greenhouse

If the soil is well-drained, Begonias will tolerate acidic, sandy, and clay soil. A proper drainage system is essential for Begonias because they are highly susceptible to stem and root rot. The best way to prevent overly wet soil from affecting your Begonias is to choose a lighter potting soil with extra perlite or mix peat moss, perlite, and potting soil together. Make sure each soil type is used in equal proportions.

Light Requirements for Growing Begonias in the Greenhouse

Planting Begonias in an area with morning sun and afternoon shade is best. Overexposure to sunlight will harm most of them. The leaves can be burned if it is too hot. Bright, indirect light is best for Begonia plants. The leaves will turn white, fade, or look burning if exposed to too much sunlight. If that’s the case, move it to a shadier area. Conversely, they don’t get enough light if the stems grow leggy and reach for the window. A grow light should be added.

Temperature and Humidity Requirements for Growing Begonias in the Greenhouse

Plants prefer temperatures between 15°C and 24°C. They prefer high humidity, which can be achieved by placing a tray of water near the plant or using a humidifier.

How to Grow Begonias From Seed

The process of growing Begonias can be done in several ways. Sprouting seeds in a starter tray, planting potted plants, or planting tubers are all viable options after the last frost. Begonias can be grown from seeds or fibrous roots in greenhouses, but ensure you know when the last frost is expected in your area before transplanting. Three months before planting, start seeds.

Seeds should be sown in a shallow container with seed starting tray and soil formula. Germination can be aided by placing the tray in indirect sunlight.
A warm climate, typically between 21°C and 24°C, is necessary to keep the soil moist and healthy for Begonias.
It should take about three weeks for seedlings to emerge.
Continue providing natural light to seedlings or grow them under fluorescent plants. Allow seedlings to rest from the heat at night by turning off the lights.
Position new growth so it has room to spread when seedlings contain two leaves each.
Once the Begonias reach their final location after the last frost, fertilize them with fertilizer after one month of growth.

Water Requirements for Growing Begonias in the Greenhouse

Watering Begonia plants properly is one of the hardest parts of successful Begonia plant care. They prefer a moist but not overwatered environment. It is sometimes difficult to strike a balance. Check if your Begonias need water before watering them on a set schedule. Make a small incision in the soil with your finger. If it feels wet, wait a few hours before watering again.

Fertilizer Requirements for Growing Begonias in the Greenhouse

Before planting Begonias in the ground, amend the soil with compost. A balanced organic fertilizer mix of 20-20-20 should be applied monthly to plants in containers and on the ground. Begonias require heavy feeding, so use an organic fertilizer with a high nitrogen level. The nutrients will be more readily available to container Begonias using liquid fertilizer.

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Mulching for Begonia Plants Growing in Greenhouse

Due to their vulnerability to rot due to wet conditions, Begonias should be mulched with caution. Plants should be mulched with bark to preserve soil moisture and prevent weeds from growing. Keeping mulch away from succulent Begonia will prevent them from rotting. Mulching is not necessary for Begonias in containers.

Trimming & Pruning Begonia Plants Growing in Greenhouse

Pinch back newly-formed growth tips when they are about 3-6 inches long to encourage fuller, bushier growth. Repeat once a month until mid-summer. If you want to grow fewer, larger flowers, pinch off new young stem growth while allowing new buds to grow into flowers. From the tip, pinch back to the second healthy bud. By deadheading regularly, you can keep tuberous Begonias looking their best and remove rotting old flowers that can cause disease.

Propagating Begonias from Cuttings

Different varieties of Begonias propagate differently, but cuttings are often the easiest method to use. Cuttings of stems or leaves can be used to propagate Begonias as follows:

Begonia should be cut four inches below a node in spring with a knife or gardening scissors. The stems should be mature but not fibrous or woody, with a few nodes to promote new growth.
The lower leaves should be removed, and the cut stems should be dipped in rooting hormone if desired.
You can create deep holes using your fingers or a pencil to fill a container with well-draining soil.
Stem cuttings should be placed in each hole and gently surrounded by soil.
You can help retain moisture by covering the entire container with a plastic bag without touching the stems or leaves. Make sure the plant has plenty of air circulation.
While the roots form, which takes about three to four weeks, keep the soil moist. Plants should be transplanted to their final destination six to eight weeks after they are started.
Cut the mature leaf where it meets the stem with a sharp knife if propagating with a large leaf. Follow the directions for stem cuttings by cutting the end of the leaf into a point.

Pests and Disease in Begonia Plants

Begonias are commonly affected by Botrytis rot, a fungus. Proper drainage can be achieved by using light potting soil with extra perlite.
Begonias can also be attacked by powdery mildew. Spray Bacillus subtilis organic fungicide on the plants to prevent mildew growth. Mix one tablespoon of horticultural oil and one tablespoon of baking soda in 4 liters of water for a natural homemade solution. It is best to use these sprays as preventative measures.
Whiteflies and mealybugs occasionally attack Begonias, especially when grown indoors. Whiteflies can be killed with insecticidal soap and mealybugs with rubbing alcohol-soaked cotton swabs.

Harvesting Begonia Flowers

A Begonia grows 12 to 18 inches tall and wide and thrives in part-shade to full-shade. From early summer until frost, they bloom with clusters of fragrant, light pink flowers, and their leaves are large, heart-shaped, and medium green. When flowers are fully hydrated, and at the correct stage of development, they are at their best. Flowers should be cut at different times depending on their variety. Some flowers should be cut when in the bud stage, while others should be cut when fully opened. In the morning, before the heat and stress of the day, flowers are the most hydrated. For the best blooms, many cut flower growers harvest early in the morning, near sunrise.

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Conclusion

A greenhouse can be an ideal environment for growing Begonias. You should be aware of several production best practices when growing Begonia varieties in the greenhouse. Growing Begonias in a greenhouse can be easier if the growing environment is managed, sanitation is maintained, and EC is monitored closely.

How to Grow Begonias in a Greenhouse: A Step-By-Step Guide for Seed to Harvest