Sempervivum Arachnoideum – Complete Care Guide

What is Sempervivum Arachnoideum?

Sempervivum arachnoideum is also known as Cobweb Houseleeks. It is a hardy, hairy succulent that grows in clusters and is endemic to the Carpathian Mountains of Southern Europe. Whether you are growing the Sempervivum arachnoideum in pots, rock gardens, or dry stone walls, the spiderweb-like appearance of the plant will grab the attention of visitors.

sempervivum arachnoideum
Sempervivum Arachnoideum @Pinterest

Not only is the Sempervivum arachnoideum easy to grow, but it is also fast-growing and adaptable to different environments. If you want to grow the Cobweb Houseleeks indoors or outdoors, this article will come in handy.

Description of Sempervivum Arachnoideum

Sempervivum arachnoideum is a creeping succulent that develops green rosettes, which grows up to three inches tall and 12 inches wide. If you nurture the Cobweb Houseleeks very well, they will reward you with pink, star-like flowers and offsets in the summer. After the flowering season, the parent succulent dies, and the offsets replace it.

If you want the Sempervivum arachnoideum to bloom, it is best not to grow it indoors.

How to Care for Sempervivum arachnoideum

For optimal growth, you need to know how to care for Sempervivum arachnoideum with regards to lighting, watering, potting mix, and temperature.

Lighting Requirements

If you want your Sempervivum arachnoideum to be happy always, you need to grow it outdoors. The succulent requires partial to full sun to thrive. If you keep under direct sunlight, do not mistake the purplish-brown color for sunburn discoloration.

If the leaves of the Sempervivum arachnoideum appear to be shriveled and dark brownish, that is a sign that the succulent is suffering from sunburn and needs to be treated to prevent further damage.

You have to acclimate the Sempervivum arachnoideum to full sun if you want to avoid sunburn. Start by exposing the plant to the morning sun for 1-2 hours daily. After about a month, you can introduce the plant to the afternoon sun for about three hours daily.

But bear in mind that a fully acclimated Sempervivum arachnoideum can still get sunburned during a period of intense heat, so you might want to take the plant indoors or use sunshades to protect it, especially when the temperature rises above 100 degrees Fahrenheit.

If you are growing the Sempervivum arachnoideum indoors, place the pot close to an east-facing window. A west or south-facing window could also work, depending on your location.

The biggest mistake you can make is to overwater the Sempervivum arachnoideum while providing insufficient lighting. This could damage the plant beyond repair.

If you notice the stems of the Cobweb Houseleeks are stretching in the direction of sunlight, quickly provide more lighting to prevent the succulent from becoming leggy. This condition, which is known as etiolation can result in stunted growth and weak leaves production.

If you live in a poorly lit environment, consider getting a grow light to boost the light intake of the Sempervivum arachnoideum.

Frost Tolerance

One of the great features of the Sempervivum arachnoideum is that it can withstand frostbite and freezing temperatures that are below 15 degrees Fahrenheit. So, you can leave the Cobweb Houseleeks outdoors all through the year if you live in the USDA Plant Hardiness Zones 5-8.

In fact, you can plant the Sempervivum arachnoideum in the ground if you live in these hardiness zones. It will survive in the rain and cold during the winter.

Nonetheless, if you would like to protect the succulent during harsh weather conditions, consider using a frost cloth or a small greenhouse.

Potting Mix

The soil you grow your Cobweb Houseleeks in determines how well they will be able to resist pests and diseases. Sempervivum arachnoideum grows best in sandy soil with good drainage. Ensure the soil pH is somewhere between very acidic and slightly alkaline (6-8).

Thanks to the long taproots of the Sempervivum arachnoideum, it can get water and nutrients from deep within the soil during a period of drought. This helps it to survive even in rocky, and windy areas. To prevent moisture from evaporating, you can topdress the soil with pebbles.

Using compost specially formulated for alpine plants is very effective for Sempervivum arachnoideum. That said, you can make your potting mix by adding horticultural grit to a shallow pot so the Sempervivum arachnoideum can crawl easily.

Watering Requirements

Watering Sempervivum arachnoideum requires skill and balance. You have to simulate the natural environment of alpines. This means you have to water the succulents at least once a week. It is best to water before sunrise or just after sunset to prevent the evaporation of moisture.

It is also recommended to water during these periods because the water droplets on the leaves might act as a sort of magnifying glass and attract heat to the plant, ergo causing sunburn.

Sempervivum arachnoideum can be resuscitated after a long period of drought. You just have to water the plant more often and deeply. For younger succulents, watering twice a week can revive them and develop stronger roots.

You do not need to water mature Sempervivum arachnoideum succulents during the winter months when they are dormant. But then, you have to water younger Sempervivum arachnoideum during this period because their roots, which help to tap nutrients from the soil are not yet fully established.

Propagating the Sempervivum Arachnoideum Plants

The best way to propagate Cobweb Houseleek plants is by removing the offsets and pups from the parent succulent. This means you have to be patient for the Sempervivum arachnoideum to develop pups before you can begin propagation.

To propagate from pups, you have to use only mature pups. As you cut off the desired pup, get some roots along with it. While you can do without the roots, they increase your chance of success since the roots are already developed. Also, stronger pups have higher chances of surviving than tender pups.

To cut the pup, place a sterilized knife between the offset and the parent succulent. Keep the pup in a dry place so it can dry and the cut can be sealed. Remember, do not expose the pup to direct sunlight so it does not get burned.

An optional step you can take is to put the pup in rooting hormone, so the growth process can be faster. This step is particularly useful if the pup was removed without roots.

Once the pup is dry, plant it on a separate potting mix and water it occasionally. Bear in mind that pups require more moisture than mature succulents. So, you have to mist the soil once it is dry. You can stop misting when the pups form roots and start watering deeply once or twice a week.

As the new plant matures, you can start increasing its exposure to sunlight daily.

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