1.        Mix equal amounts of garden soil, sand and broken brick perlite. Sterilize prepared substrate by putting it in a microwave for 3 minutes or in your oven for 45 minutes approximately.

2.        Previously prepared containers for planting are to be filled with substrate, but while doing it, be careful and leave some space at the top, at least 0.5 inches (2cm). Add plenty of water and leave the container, so that the water has some time to decant.

3.        Plant Agave seeds, but leave at least 0.4 inches (1cm) of space between each seed. Then cover the seeds again with a thin layer of substrate, and to finish it off, cover it with a thin layer of fine gravel, with grains no bigger than 0.12 inches (3mm). Water it again.

4.        Moisture is the most important part for seed germination. It’s best to cover the container with a piece of nylon or a plastic bag in order to keep it moisturized. The container with seeds should be put somewhere warm, but not exposed to direct sunlight. The temperature needed for Agave to germinate is 77°F (25°C) and above.

5.        The germination can start as soon as 4 days after planting, but it’s more frequent for it to start after 10-12 days. Remove the glass that kept the container moisturized 2 weeks after planting.

6.        You need to spray the substrate every day, it cannot be let to completely dry off. It is also important to provide the plant with sufficient sunlight during the day, but avoid direct sunlight for a couple of months. It’s of great importance for Agaves not to change its light regime during this sensitive period. Try to provide it with a similar amount of light every day.

7.        Agave’s seedlings have a tendency to fall over, which can be fatal for them. You can prevent that by adding some pebbles around the plants. Agaves bred from the seed start off as one leaf. The empty shell of the seed can stay at the top of the plant for a long time. You can take it of gently by yourself, but it’s not necessary. The plant starts to form a new leaf four weeks after germination, so they start looking like mature Agaves. However, only after forming the third leaf will Agaves look more like their parents.

Agave havardiana is a wonderful cold-hardy Agave that with care and the correct cultivation will survive in UK gardens through the cold wet rigours of a British winter. It suckers, but tends to be slow to sucker, so easy to keep control of. Because of its compact size, plus its low water use and low maintenance, it is considered a good landscaping plant for desert residential landscaping.
Growth rate: Slow to medium growing, but speeds up considerably given the best conditions. 
Exposure: They do well in full sun or a lightly shaded area with afternoon shade.
Soil: They do best in very well-drained, sandy or gravely soil. As an ornamental it is also grown in containers where it stays smaller than its outdoor brethren. In pots they need a very porous mix soil (e.g. 2 parts peat moss to 1 part loam to 1 part of pumice). 
Repotting: Use pot with good drainage.
Fertilization: They grows quickly if kept well nourished with a slow release fertilizer specifically formulated for cactus and succulents applied once or twice a year (poor in nitrogen), including all micro nutrients and trace elements.
Hardiness: Agave havardiana is hardy to -7 to -12° C depending by clones