Morning, FF, here comes the punch..lol, kidding. I agree, when roots fill a pot 'X' plants should be repotted in larger containers. However, imo, transplanting from a 4" pot, to let's say 8" or larger is a no-no. Plants that are naturally tiny, 'ex: miniature African Violet, Lithops, Crassula elegans needn't be potted in containers larger than 4". Shallow-rooted plants, when repotted, require wider, not deeper containers. TC's have shallow roots. Ever go to a conservatory? Our conservatory set-up is as close to various plants' natural habitat as possible. TC's/CC/Epi/certain Orchids, are either attached to trees or in-between rocks. Depending on type. After studying roots I discovered they're not all that large. Just my opinion. :) PS...I'm not saying TC's won't grow in a large pot. Often,, during summer when plants are outside, they're knocked down, brushed against, squirrel attacked, etc. TC segments break, land in a neighboring containers, some as large as 14". Yet, segments root. Still, imo, TC/CC/EC bloom when root bound. :) Toni

You could graft the wee ones onto the green stock plant or onto a new stock plant. Leslie is quite right regarding the fact that they cannot survive on their own (they lack chlorophyll and thus are incapable of producing enough food via photosynthesis).

You're in zone 8, I'm in 8b (central Texas). I wonder whereabouts are you? It's, rule of thumb, better to provide full watering rather than 'sips'. Today, it's sunny and a high of 57F. I haven't watered any of the Mammillaria at my home in over a month. I probably won't water those until March. Remember that these types of cacti (the heavy barrel shaped) can go extremely long periods of time between watering. By long, I mean a year in my zone in a similarly sized pot and soil (a bit water retentive) before showing drought stress. As long as you provide bright light in a western or southern window (or your brightest window), you can likely and safely forget about it. Just rotate the pot once every other week to prevent leaning (which is probably what it's doing now- which is not a great concern). One of the problems with that type of soil and withholding water for so many months is that the substrate itself may become hydrophobic and when you do take up watering again, water may drain slowly and even simply sit up top for quite a while. If you don't want to change the soil: What I would do in spring after the cacti start producing flower buds: I drench the soil with water that has a surfactant to break that hydrophobicity (a soap like Dr. Bronner's or detergent like Dawn (no bleaching agents)) and a very weak concentration of a high phosphorous and low nitrogen fertilizer (1/10 of the package recommended dose and I add a tsp of soap per gallon of water). This will aid in bloom development and prepare the soil for active growing conditions. The soap will not effect the plant, just the soil. Keep the pot under some cover to prevent rain access but in a spot that allows lots of light. Mostly, I would suggest repotting in a coarse mix. Home Depot and Lowe's carries a cacti and succulent potting mix for about $5. It will do the job. There are far better soil options, but they are a bit more time consuming and expensive to locate and gather materials. Since you stated that this is your first experience with a cactus, I will assume you are a beginner and that these other options may not yet apply to your interests and life bandwidth. Though, you can google shop for 'gritty mix' and determine if the price is viable for you. Push come to shove, you can convince me to ship you some mix for shipping cost- I appreciate your new interest and concern ;). And information on a grittier mix will be available for you on this site as good reading when you are ready. I'm also keen to resources for getting the ingredients for a gritty mix. Should you choose to repot, put on some protective gloves and hose off all the old soil from the roots. Don't be afraid to blast off the peat and take the roots to 'naked'. Allow the roots to dry for a day in a protected area (dry and frost free, preferably with good air flow). Repot in the mix of your choice. Do not water until you see signs of growth (or until March). Zone 8 is quite warm. I want to suggest taking your cactus outside on nicer days, but then we run the risk of forgetting on cold nights and I don't know how your Mammillaria will fare in freezing temps.

My small Ruby Ball Cactus has developed small brown lines on the top, in the ridges. Also a yellowing on the small tips near the top. I am worried about it and wondering if it could be sunburn or something else. Also I have another cacti, turning a yellowish brown towards the bottom. I've had it for almost 2 years, bought it from a store on Route 66 and don't want it to die! Please help.