The best maintenance-free hardy rock garden succulents are those that are frost and sun resistant.Most cultivated succulents are cold sensitive.In fact, only a few are truly hardy, such as Sempervivum, which can withstand down to -20°C.Some agaves such as Agave victoriae-reginae (down to -10°C), or Sedum spathulifolium resist down to -18°C.Therefore, before starting with the list, we advise you to do a little research on the climate in your area.It is very important to know the lowest and highest temperatures.If, for example, there is snowfall, it is better to have succulents in pots so that you can protect them from the cold.And that said, guess which succulents we recommend growing outdoors.Hardy succulents are resistant to direct sun and coldAgave victoriae-reginae is an outdoor succulent.It is a plant 60 centimeters high and about the same width.Its leaves are fleshy, green and grow in a very compact rosette.It is very beautiful when planted in informal groups as well as in ensembles.Agave victoriae-reginae down to -10ºCAloe arborescens is a perennial succulent plant.It is a shrubby succulent that develops branching stems.It grows up to 3 meters in height, although it is normal not to exceed 2 meters.Its leaves are green and form rosettes, in the center of which grow flowers of intense red color.It is a shrub that is recommended to be grown in the ground, because in pots it is very small.It is one of the most cold-hardy types of aloe.Aloe vera can withstand down to -4°CDudleya britonii is a sun-tolerant succulent.It is a shrub that develops a branched stem that reaches 1 meter in height.From it germinate rosettes of elongated leaves.They are covered with a kind of white powder or wax measuring about 25 centimeters in diameter.We advise you to plant it in a rockery or in a lush garden, where it can grow better than in a pot.It withstands temperatures down to -5ºCLilac echeveria is a succulent that is resistant to direct sunlight.It is a shrub that reaches a height of 15 centimeters and a width of up to 25 centimeters.It forms a rosette of succulent pink-green leaves.Its flowers are red or coral red and grow from a stem approximately 15 centimeters high from late winter to early spring.It is a plant that you can put it in a pot that is wider than tall, because it will be able to grow much better.It resists both drought and frost down to -3°C.Euphorbia millii is a sun-tolerant succulent shrub.It is known as the Crown of Christ.It is a lush evergreen shrub that reaches a height of 1.5 meters.It develops thin prickly brown stems and lanceolate green leaves.The tips are straight, 1-2 cm long.We therefore advise you to wear protective gloves whenever you work with them.The flowers are red, but there are varieties that produce them white, yellow or orange.It does not require much care and can live in sunny places.It supports drought and light frosts down to -3ºCHesperaloe parviflora, known as red yucca, is an outdoor succulent.It is a type of non-cactus succulent that reaches a height of between 90 centimeters and 2 meters.It has elongated, leathery, green leaves, from which white "hairs" grow.Its flowers are red and grow from a tall stem, up to 1.5 meters, in spring and summer.It resists up to a temperature of -5ºCSedum spathulifolium is a small shrub reaching a height of 10 centimeters.It develops strongly branching stems from which grow green leaves, although the edges may turn reddish if the sunlight reaching them is very strong or from cold weather.That's why you don't have to worry about it.It resists well down to -18º CKalanchoes are recognized as the best-selling succulents in the trade.You can buy it at supermarkets, home centers and nurseries.Most often they are sold as a houseplant.However, it can also be grown outdoors in milder climates.Most are no more than a few feet tall and work well in patio pots or indoor containers.They bloom with bright, long-lasting flowers from fall through winter.Their textured foliage adds to the spectacle at the rockery