Rex Begonias

Cultural Information

Immediately Upon Arrival:

  • Water
  • Plant liners at the same soil level
  • Provide DEEP SHADE and WARMTH for 2 weeks.

Failure to take these steps may kill your plants. Rex Begonia roots are delicate, brown in color, with tan tips. Use care when transplanting.

Ideal Planting Conditions for Rex Begonias

For the first two weeks, you must provide a mild warm environment similar to a fern house:

  • 65-75F nights    Temperatures much like those of a humid fern house.
  • 900 ft candles    Light level so low that you cannot see a shadow under your hand
  • 70% RH               High humidity

Keep leaves dry to avoid Botrytis and bacterial disease development. After the roots are well established in your potting mix, you may move the plants to a cooler, drier, brighter production house for finishing alongside with shade perennials, for example.

If you plant Rex Begonia plugs too high, salts will accumulate in the plug and will burn the roots. This happens because the plugs act as ‘water wicks’ when planted too high, drawing water out of the soil, and concentrating the salts as the water evaporates from the plugs. At the other extreme, planting the plugs too low will rot the rhizome. Plant the plugs at the same level as the potting soil, or 1/8th inch below.

Ideal Growing Conditions for Rex Begonias

  • Moisture: Even, never dry.
  • Fertilizer: 150-180 ppm N constant feed.
  • Salinity: Never exceed an EC of 2.4. An EC of 1.5 is ideal.
  • Light: 1200 to 1500 foot candles.
  • Night Temperatures: 65F+ Nights to establish. 55-65 Nights to finish.
  • Day Temperatures: 70-95F. If daytime temperatures exceed 80F, reduce light to 1200 ft candles.
  • Insect Pests: Aphids. Mites.
  • Diseases: Botrytis, Xanthemonas Bacterial Leaf Spot. Apply a preventative spray of any metallic fungicide every two weeks to avoid these problems.

Finishing Times for Rex Begonias

Pot Plugs Weeks
4″ 1 8
5 1/2″ 1 12
6″ 1 16
6″ 2 12
8″ 3 12