Mammillaria karwinskiana - Royal Cross

$9.99

SKU:C2JY4739

$9.99
  • Mammillaria karwinskiana - Royal Cross
  • Mammillaria karwinskiana - Royal Cross
  • Mammillaria Karwinskiana Royal Cross Blooms
  • Mammillaria Karwinskiana Royal Cross Blooms Alt
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Product Details

Highlights

Mammillaria karwinskiana - Royal Cross (Martius): A solitary, Mexican cactus that occasionally branches. It has tufted white hairs nestled between raised tubercles and white spines. At the top of this stem, the spines thicken, elongate and redden to copper. It stays under 4.0" tall and wide and blooms with a crown of cream colored, funnelform flowers. This plant is fully rooted in a 3.5" pot.

This cactus variety will not survive a hard frost, but if there is a risk of freezing temperatures it can be brought indoors to grow on a sunny window sill or under a grow light. Cactus need bright sunlight, great drainage, and infrequent water to prevent rot. Pick containers with drainage holes and use well-draining cactus and succulent soil with 70% to 80% mineral grit such as coarse sand, pumice, or perlite. Water deeply and wait for the soil to completely dry out before watering again.

Full Cactus Guide

Product Size

3.5" Pot

Current Primary Color

Green

All Seasonal Colors

White

Bloom Color

White Bloom, Yellow Bloom

Grow Zone (Hardiness)

Zone 10 (30F)

Recommended Light Conditions

Bright Indoor Light, Full Sun

Maximum Height

3"-5"

Growth Habit / Shape

Clumping / Mounding

Special Characteristic

Hard to Kill, Slow Grower, Showy Blooms

USDA Zone map for average annual extreme minimum temperatures

THIS PLANT IS HARDY IN ZONES 10+

10

WHAT IS MY HARDINESS ZONE?

0

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Questions & Answers

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Popular Questions

3 years ago
3 years ago
This Hanging Urchin does not need to be planted, as the Air Plant that's in the urchin does not grow in soil. It can simply be hung in a sunny window and regularly watered. The video at the link below will give you lots more info on Air Plant Care.
Source: https://youtu.be/oOo9p9lO2TA
2 years ago
Product details See more »
2 years ago  •  Staff Answer
It does not. This product is just the urchin shell and the air plant.
2 years ago
2 years ago  •  Staff Answer
They vary between 2" and 2 3/4" in diameter, making them, roughly 12.6" to 17.3" in circumference.
1 year ago
1 year ago  •  Staff Answer
The urchin shell is 2" to 2 3/4" in diameter and does not grow, but the type of Tillandsia inside varies, so the size varies.
2 years ago
I don't live near open water, where could I find the root containers to hang a few of these "air plants"? I'm not a guest but would like a fast result as my mother-in-law is coming & I think she'd enjoy these in her room. See more »
2 years ago  •  Staff Answer
An order of this product includes the sea urchin container. We ship on Mondays and Tuesdays to arrive by the weekend, but you can also select faster shipping options during checkout.
1 year ago
1 year ago  •  Staff Answer
The urchin shell has a small hole in its top. This way, you can get creative with fishing line and paper clips, or any sort of decorative hook. Here's a tip; try using low gauge, clear fishing line. That'll be easier to hide.
8 months ago
I've lost a lot of air plants to mold. I make sure they are dry before replacing them in their holders but they still die. Also, I want to put them in those shells and hang them but do I have to take them out each week when I soak them and then put them back? I really love the look but I am getting frustrated because they keep dying on me! See more »
8 months ago  •  Staff Answer
Increasing the amount of light helps fight mold and may be just what your plants need. You could also try misting your plants thoroughly 3x a week instead of soaking them once a week. That would help them dry even faster. That second tip goes double if your house is naturally humid or you're using a swamp cooler.
4 years ago
4 years ago  •  Staff Answer

Shop Succulent Soil Here

Succulents need grittier soil than other plants because they are adapted to dry conditions and store water in their leaves. Regular potting soil mixes stay damp for long periods of time, which can cause rot in succulents. Instead, use a sandy, well-draining soil so you can water thoroughly without leaving your succulent in standing water.

IN POTS…

See full answer »
4 years ago
4 years ago  •  Staff Answer

Our plants can be transplanted immediately upon arrival.
If you want to wait to transplant, they can remain in their original containers for up to a month. If the pots came in a plastic carrier tray, remove the pots from the carrier tray prior to the first watering.

Keep the plants indoors near a sunny window or outdoors under a roof (only if outdoor temperatures stay above your succulent's minimum hardiness temperature). Water only after the soil is fully dry by drenching from above with a faucet, hose, or watering can. Gently shake excess water from the leaves and allow containers to drain completely.

4 years ago
4 years ago  •  Staff Answer

Fertilizing is not necessary, but it is a good option for succulent growers who want to encourage faster, larger growth. It can be used on mature plants with established roots. Only fertilize in the growing season (spring and summer for most varieties) to avoid weakening or burning dormant plants. Use a light touch and make 2-3 applications of low-Nitrogen, diluted fertilizer each year (N-P-K ratio around 5-10-10). You can find specially-formulated cactus / succulent fertilizers in most garden centers or go organic with compost tea or bone meal.

Example: Miracle-Gro Quick Start, diluted to half strength

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Shipping info

  • Shipping Days: Monday, Tuesday
  • Same Week Shipping Cut-off: Monday 11:59PM PT
  • Delivery Days: Usually the following Thursday or Friday
  • Delivery Date Requests: Use the comments box during checkout
  • Why don't we ship every day? This schedule avoids weekend delays and helps us ensure the plants are delivered fresh

Click here for more shipping and ordering info.

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May 12, 2025 by kate C. (United States)
“easy and a lot info about the plant”
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