A Golden Barrel Cactus (Echinocactus grusonii) does not really need to bloom to have a commanding presence in the garden. The symmetrically rounded stem is armored down the ridges with clusters of golden yellow spines. A wooly white patch tops the older cacti. This is the central growing point and bears the small yellow flowers. Growing in USDA Plant Hardiness Zones 8 through 11, these long-lived slow-growing cacti can reach 3 feet (0.9 m) across and 4 feet (1.2 m) high. They are suitable for container plants anywhere.
The life cycle of the Golden Barrel Cactus starts with the flowers that need to be pollinated to produce seeds. Yellow funnel-shaped flowers grow in a ring in the central felted portion. Plants must be at least 14 inches (35 cm) across before they are old enough to flower. Sometimes the flowers are self-fertile, but you get more seeds when flowers cross-pollinate with those on another Golden Barrel Cactus. Bees are the usual pollinators. Once flowers are pollinated, they close, and seeds begin to form in the ovary beneath the faded flower.
The fruits are embedded within the dense plant hairs on the top of the plant and remain in place year after year unless you pull them out. Sometimes ground squirrels harvest them to eat the seeds. The dried flower stays on top of the fruit. The fresh fruit has a yellowish fleshy wall that dries to brown. The oval black seeds inside the fruit remain viable for a long time. To collect the seeds, gently remove the fruit by grasping the dried flower and slightly twisting it as you pull. It is best to take fruits to a work table to break them open and remove the seeds.
Seeds germinate during warm moist conditions and need light to sprout. To sow the seeds, use a clean, shallow pot with drainage holes and a soilless growing mix like half peat and half perlite. After filling the pot within an inch (2.5 cm) of the top with the potting mix, scatter some chicken grit on top and then evenly distribute the seeds, so they lodge among the grit. Water the pot from the bottom by temporarily putting it in a water tray, so the mix is thoroughly wet. Cover the pot with plastic and place it in bright indirect light, keeping the soil moist but not soggy.
Pudgy little seedlings emerge from the seeds after four to six weeks. They look like miniature greenish-pink pencil erasers with a pair of pointed corners, which are the cotyledons or seed leaves. As the seedlings grow, a puff of tiny spines develops on a bump between the cotyledons. Gradually remove the plastic after the seeds have germinated. Allow them to grow until they are big enough to touch each other and have a small crown of spines, when you can transfer them in small clumps of four to six plants to individual 2-inch (5 cm) pots. Being in clumps helps to keep them from being overwatered.
As the seedlings grow, they begin to look more like cacti. Plants have little bumps with a cluster of small spines atop each bump, more properly called tubercles, that eventually join together to form the ridges on the cactus. When your seedlings fill the pot, unpot them, separate them and give each one its own 2-inch (5 cm) pot. Each time they grow to touch the sides of the pot, transplant them to just the next pot size and gradually give them partial sunlight. When cacti are 6 inches (15 cm) wide, they can be gradually accustomed to garden conditions and planted outdoors. After about 15 years, the plant becomes large enough to flower, and the cycle repeats itself.
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