Actual size and flowering may vary slightly based on season.
Blue Monstrosus Cereus
Blue Monstrosus Cereus is the monstrose form of the night-blooming cereus, with blue-green, ribbed columns covered in knobs, bumps and odd twists. It grows slower and stays smaller than the regular form, but it can still branch into a sculpted clump 10 to 20 feet tall over many years. On summer nights it can open large white flowers, followed by edible red fruit. Use it against a plain wall, by an entry or in a big planter.
Best for: a sculptural accent against a tall wall or building, entries and raised planters, and large containers with other cacti.
The knobby, contorted columns stand out against a tall wall or a large, plain building face. Give it 12 to 20 feet from other large plants as it fills out.
It grows slower than regular night-blooming cereus, so it holds its shape in an entry bed or raised planter for years.
It works in large containers alongside other cacti and succulents. Potted plants need water more often than plants in the ground.
It is hardy to about 18 to 20°F and freezes in the low teens, so cap the tips on frost nights. Soggy soil rots the roots, so plant it where water drains away.
- Closer planting12 ft apart, center to center
- Wider planting20 ft apart, center to center
Wait about a week after planting before the first water. Then water every other week while nights stay above 60°F. In cooler weather, water only after two to four weeks without rain.
Water deeply in the warm months only when the soil is dry, and give little or none in winter. Plants in pots dry out faster and need water more often than plants in the ground.
Plant it with the same side facing the sun as in the nursery. Cover a new plant with light shade cloth its first summer, then remove it.
Below about 18 to 20°F, frost can scar the stem tips. Cover the tips with foam cups or frost cloth that reaches the ground, not plastic. Take covers off in the morning.
Now and then a normal, round stem sprouts from the plant. Cut it off at its base so the plant puts its energy into the knobby growth.
Drainage test first. Dig the hole and fill it with water. If water is still sitting in the hole a day later, you likely hit caliche, clay or hard soil, so fix the drainage before planting. If it drains very fast, the soil is sandy. Standing water around roots is a common reason new plants fail.
Weed cloth. Cut it away from the planting hole and where the roots will spread. Remove any plastic sheeting completely, since it keeps water and air out of the soil.
Rock or decomposed granite with no soil underneath. Bring in soil close in texture to your native soil, mix it with the soil below, and build up enough depth for roots before planting.
If you can break through. Use a breaker bar, pick, or jackhammer. Dig through the caliche and break out the solid chunks. Backfill with the soil you dug out, with no compost or manure in the hole. Confirm drainage before planting.
If you cannot break through. Dig narrow holes through the hard layer beside the root ball, not under it, and refill them with the same soil, not gravel. If it still will not drain, plant on a low mound of the same soil.
Root ball. Check the outside edges for any roots circling around. Loosen or cut those so they grow outward. Do not break up the center of the root ball.
Depth. The top of the root ball should sit at or just slightly above the surrounding soil level. Planting too deep can lead to rot and kill the plant.
Drip emitters. At planting, put the emitters on the root ball, on different sides of the plant. After about 2 months, move them to the outer edge of the root ball. Over the first year, add emitters farther out toward the edge of the branches as roots grow. Once a plant is rooted, never water only at the trunk.
What makes a cereus monstrose?
A monstrose plant grows from many points at once, so the columns turn knobby, bumpy and contorted instead of smooth and straight. Each plant develops its own shape.
How is it different from regular night-blooming cereus?
It is the same plant in monstrose form. It grows slower and smaller, with knobby blue-green stems, but has the same night flowers and fruit.
How big does it get?
It can slowly reach 10 to 20 feet tall and 6 to 15 feet wide, though it stays smaller than the regular form. Plan the spot for that final size.
How far apart should I plant it?
Plant them about 12 to 20 feet apart. The Spacing tab shows the details.
Does it flower?
Yes. Large white flowers open at night in summer, and red fruit follows. The fruit and its small crunchy seeds are edible.
How often should I water it?
Water it about every month or two in the warm season, and less in winter. Plants in containers need more water.
Is it cold hardy?
It is hardy to about 18 to 20°F and freezes in the low teens. Cover the stem ends with foam cups or frost cloth on frost nights.
Does it need full sun?
It grows in full sun to part shade. Keep a new plant's sun side the same and shade it lightly its first summer.
What if a normal, smooth stem grows out?
Monstrose plants can send up normal stems. Cut the smooth stem off at its base to keep the knobby look.
What soil does it need?
Plant it in sandy, fast-draining soil, and never let it sit in soggy ground.
Blue Monstrosus Cereus for sale in Arizona, delivered to you
Blue Monstrosus Cereus is a monstrose night-blooming cereus, grown for its knobby, blue-green columns. It is slower and smaller than the regular form and reads as a living sculpture. Below are the questions Valley homeowners ask about it.
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Monstrose cereus in Phoenix landscapes
This knobby, blue-green column cactus reads as a living sculpture against a tall wall or building. It also suits entries and raised planters.
Blue Monstrosus vs night-blooming cereus
It is the monstrose form of the same cactus. It grows slower and smaller, with knobs and bumps along each column.
How big monstrose cereus gets
It can reach 10 to 20 feet tall and 6 to 15 feet wide over many years. Space plants 12 to 20 feet apart.
Watering monstrose cereus
Water about every month or two in the warm season and less in winter. Water potted plants more often than plants in the ground.
Frost care for monstrose cereus
It is hardy to about 18 to 20°F. Cover the stem ends with foam cups or frost cloth on cold nights.
Monstrose cereus flowers and fruit
Large white flowers open at night in summer. Red fruit follows, with small edible crunchy seeds.
We deliver across the Valley, from Phoenix, Scottsdale and Mesa out to San Tan Valley, Maricopa and Casa Grande, and up to Prescott, Sedona, Payson and Globe. See delivery areas and rates.