How to Take Care of Moss Roses
To take care of moss roses, water them deeply once a week, or wait for the soil to dry out completely before each watering. Once the plants are established, remove dead flowers by pinching their stems and pulling them off so the plant can replace them. You will also need to weed the bed weekly so the plants don't get chocked out. Then, replant the roses every year since they are annuals.
Find out if moss roses are right for you. Moss roses are well-known for their combination of beauty and durability. They suit most climates well, and amply reward their caretakers with amazing blooms. However, they do have a few quirks, so double-check to make sure your garden can support them. Moss roses are succulents, storing water in large, fleshy leaves. This means that they will be fine if you forget to water them. They can grow in poor soil or even rock gardens. However, they might drown in a very rainy climate. Moss roses are low-lying, rarely topping six inches in height. They are good for borders and pots, but do not command large-scale attention on their own. Moss roses can absorb the carbon dioxide from car exhaust especially efficiently. This means that they are sometimes used to line driveways, or parking lots. Though some varieties are edible to humans, moss roses are toxic to pets. Do not plant them where a dog or cat can snack on them. Plan out your planting. Now that you know you're ready for moss roses, it's time to figure out where to put them. Since moss roses love sun, make sure they will get full sunlight for at least part of the day. If you are planning to use them in a flower display, plan to put them in front, as portulaca plants are low-lying. To know how many moss rose plants you need for a border, measure the length in inches and then divide by 12. Your plants should be spaced about 8 to 12 inches (20 to 30 cm) apart, so dividing the total measurement in inches by 12 will give you the approximate number of plants that you need to fill the border while still keeping adequate space between the young plants. Don't worry; moss roses grow fast, so you won't have gaps for long. You don't have to plant moss roses outside. They are pretty in pots, too, as long as they get plenty of sunlight. Decide if you want seeds or seedlings. If you are a more confident gardener, you may already be planning to work with seeds. If you would prefer to begin your garden with a little bit of a head start, seedlings may work for you. There are pros and cons to each, so think about it and decide which suits you better. Seeds are cheaper, and you can start growing them (indoors or outdoors) whenever you're ready. However, it can be difficult to wait two weeks for them to germinate, and then an additional month until they're sturdy enough to move. Seedlings are convenient and already healthy, but because a greenhouse has done the work of germination for you, they are often expensive. Get your flowers. You can buy moss rose seedlings at any local greenhouse, since they are popular summer plants, though they may be tricky to find in grocery stores. Seeds can also be found in greenhouses or garden supply stores, or well-reviewed online shops. Grow seeds indoors. If you're using seeds and experiencing a long winter, you should start growing inside. This will keep the seedlings warm and protected until you're ready to plant them outdoors. Your specific seed variety will probably have instructions, but in general, moss roses grow in similar ways. Place seeds uncovered on shallow dry soil (a few inches deep is fine) and keep at room temperature. You can sprinkle them with a little water every few days, but they don't need much. The seeds should germinate within two weeks, but wait an additional month before you move them. Wait until after the last frost to plant outside. Moss roses are used to balmy summer climates. As hardy as they are with little water, a cold snap can easily kill them. Keep seedlings inside until you're certain the ground won't freeze. Treat them as you would if they were outside--make sure they get full sun and a sprinkle of water every now and then. Plant outside. Once the frost is gone for good, it's time to plant your seeds or seedlings outside. Make sure to space them out (12 inches, or.3 meters, is great) and cover them with minimal soil. They should be thriving in no time. If you live in a warm area, you can plant seeds directly--just scatter them on the ground and cover with a little seeding soil. If you're transplanting home-grown or commercial seedlings into the warmed ground, dig a small hole twice to three times as wide and equally as deep as the container the seedlings are in, then lift up the plant by its base and place it into the hole. Make sure that the roots are set. Plan to baby your moss roses for their first few days outside. For about a week, water them on a daily basis, since the roots have not yet expanded to fill the full area needed to get water to the whole plant. After this first week, you can water them less frequently. Water your moss roses. You should try to mimic desert rain habits by watering the plants thoroughly, and letting them dry out before watering them again. Watering them about once a week will usually work well. Make sure they don't experience too much runoff from other plants that need more water. Keep away from pets. Not only would it be a tragedy to lose the flowers, but they could poison the animals you know. You probably already planted the seeds where they couldn't be reached by your own pets--make sure to prevent other pets in the neighborhood from running amok through your garden, too. Deadhead your plants. This is one of the few tasks you will have to do for your portulaca on a frequent basis once your plant is settled. Manually removing blossoms that have gone to seed ensures that your plants replace dead flowers. To deadhead, take a firm hold on a dried-up bloom, and them pull steadily. It will come off, leaving room for new blooms. Save a few of the heads if you want to reuse the seeds next year. The seeds will need to completely mature on the plant. Do not deadhead the plant if you plan on saving seeds.  Weed your plants. Moss roses are nearly as versatile as many weeds, but they can still be choked out if you don't remove invasive plants. Weed weekly at the very least, for the amount of water your garden gets, and its fertility, are both factors in how many weeds your garden will attract. Repeat the process next year. Most moss rose varieties are annuals, which means that they don't live past the autumn. You can replant them next year. Just crush the old flowers to reveal the seeds, then place them in an envelope and keep it in a cool, dry place until next year. 
Find out if moss roses are right for you. Plan out your planting. Decide if you want seeds or seedlings. Get your flowers. Grow seeds indoors. Wait until after the last frost to plant outside. Plant outside. Make sure that the roots are set. Water your moss roses. Keep away from pets. Deadhead your plants.  Weed your plants. Repeat the process next year. 