Well, the best time to repot is in spring or autumn. To repot in summer or winter it only should be done if it's really necessary.

Reasons to repot

There are a couple of reasons to repot. If the pot became too small, the substrate looks rotten or you suspect that the roots are ill.

When the new sprouts don't have enough space in the pot, it's time to repot. You either can take then a bigger pot or divide the plant. With some experiances you will find out when it's time to put the plant in fresh substrate. Rotten substrate doesn't dry well and has no air movement. If you can grab a whole in the substrate with your finger, it's rotten and should be exchanged.

If your orchid looks ill, it 's good to inspect the roots . You might cut the rotten roots , take a fresh pot and fresh substrate. If the old pot still is good, you can wash it with soap water and desinfect it and use it again.

Baby plants you must repot more often. You start with a very small one and repot its in more and more bigger pots.

Material

Take either a fresh pot or clean and desinfect the old one. For monopodial growing plants you can get the same size of pot. For symbodial orchids you might need a larger pot or you divide the plant. Most of the orchids grow well in plastic pots. Some orchids like a clay pot. The substrate drys quickly . If you use transparent plastic pots, you can observe the roots very well. You can use a planter for your orchid for decoration but it should be a bit bigger that the pot and should have a drainage on the bottom. If you put some stones in and a bit water, you get a better humidity.

Substrate

Most of the Orchid Shops sell substrate. They normally offer a good mix for Phalaenopsis , Cattleyas etc. Or they offer a special mix for Paphiopedilum. Profis like to mix their substrate itselfs.

Principle

Take the orchid carefully out from the pot. They are not coming out easely sometimes cause the roots stucks at the pot. Try then to shake and turn the pot. Don't panic when some of the roots break. Cut then with a sharp scissor the old roots, the rottens stuff etc. away. The scissor should be desinfected before you use it. After this, you can clean the roots under running water and watch them if they are ok. Repot then the orchid in a new pot and fresh substrate. Does it have long roots, you put them in the pot and while filling the substrate in, you turn the pot. The long roots finds then enought space in the new pot. Press the new substrate carefully in the pot, tamp the pot a bit on the table so the substrat falls at the bottom. Watch out that the new bulbs are free and not covered. Do you have a plant with just a few roots and the plant has not a good hold, fix it with 2-3 wood sticks from every side. You can take the same one you use for the long spikes to held. As soon as you plant made new roots and stands itself you can take the help sticks out. If the repotting is done, wait a couple of days with watering. The "wounds" at the roots will be healed in these days and there is no danger for rotteness of the roots.