Cactus Ferocactus glaucescens Inermis

Characteristic: 

Ferocactus glaucescens ‘Inermis’ (also known as Blue Barrel Cactus) is a unique, almost entirely thornless variety.

The plant has a spherical, then later columnar, bluish-green or dull gray color with age. It has prominent, deep ribs (usually 11-15). The ‘Inermis’ variety is characterized by a smooth surface. Although young specimens may have a few, vestigial thorns, these usually disappear completely as the plant matures.

It produces funnel-shaped, lemon-yellow flowers, approximately 3-4 cm in diameter, that appear at the top of the plant in late spring and summer. Flowering usually begins when the cactus reaches about 13 cm in diameter. Indoors, it typically reaches 15-30 cm in diameter, although mature specimens can grow to about 50-60 cm in height.

Light: Requires full sun. In very hot climates, it may appreciate light shade in the afternoon to avoid burns.
Watering: Very sparingly. Water only when the soil is completely dry. In winter, watering should be discontinued completely.
Soil: It should be highly permeable and mineral, such as a specialized mix for cacti and succulents.
Temperature: It grows best at 20–35°C (68–95°F). It is frost-sensitive and should not be exposed to temperatures below 5–10°C (41–50°F).

Pot diameter:

Plants in 5,5 cm pots

Notes: 

It is sample photo, to show size and condition of offered plants