Please can you you help with the following

I recently purchased a cactus (see picture Below) I was given to names either mammillarias – polythele and the succulent plant is a sedum or Crassula and Echinocactus

I was also told two different methods of feeding which are as follows:

1. As far as watering goes, you should give it a small amount, about half a mug every 10-14 days in summer and reducing down to a 1/4 mug every 20-28 days over winter.

from summer hill garden centre
2 Water once a fortnight March to October – suggest a cupful ( not a mug!!!)
October to March ignore it
Feed every month from March to October ( amount should be on whichever feed you get)
October to March do not feed

from Craig House Cacti

Please can you give me the correct name and how often I water it and feed it and
where I buy the feed

I am disabled and never looked after one.

Thank you, Mark

Mark,
The cactus is a Mammillaria and the succulent is a Sedum. From the name of the nursery, I take it you are in Essex in England.

It’s going to be hard for me to give you exact instructions since I can’t tell what they are planted in. Terrariums are always a bit tricky, but it looks like maybe they are in small pots inside the glass surrounded by gravel. Assuming this is true, you want to make sure when you water that you only water right around the plant itself so that the water gets into the soil.

It won’t take a lot of water, maybe only a tablespoon per plant, but because it is so little water, you will need to water every week. You can water the cactus every 2 weeks in the winter, but the Sedum will want regular water year round. Make sure you don’t overwater – you don’t want any water sitting in the bottom of the glass.

As for feeding – Very little! since it’s in such a small terrarium. I would use a low strength liquid fertilizer like Liquid Seaweed (We use Grow More brand) and use only a tiny amount, no more than twice a year in spring and summer.
Good Luck,
Peter