If planting in the ground, Siberian elm mostly relies on rain. However, if there is no rainfall for 2-3 weeks, you may need to give proper consideration to giving the plants a deep watering. If watering Siberian elm in summer, you should try to do it in the morning. A large temperature difference between the water temperature and the root system can stress the roots. You need to avoid watering the bushes when it's too hot outside. Start mulching them during the spring when the ground is not too cold. The age of the plants matter. Lack of water is one of the most common reasons the newly planted ones fail to grow. After they are established, you need to ease off the watering schedule. Reduce watering them during the fall and winter, especially if they have a water-retaining material in the soil. The dry winds in winter can dry them out, and the newly planted ones can be at risk of drought during windy winter, summer, and fall. Windy seasons mean that there's more watering required. The ones planted in the pot tend to dry out faster, so they need more watering. Once you see that they bloom less, the leaves begin to dry up. Potted plants are relatively complex to water and fluctuate in frequency. Always be careful that the pot-planted plant don't sit in the water. Avoid putting them in containers with saucers, bowls, and trays. Too much watering in the fall can make the foliage look mottled or yellowish. It's always a good idea to prevent overwatering them regardless of the current climate or season that you might have. During the months when Siberian elm begins to flower, you might want to increase the watering frequency but give it a rest once they are fully grown. Give them an adequate amount of water once every 3 to 5 days but don't give them regular schedules. Make sure the soil is dry by sticking your finger in the pot, or use a moisture meter if you're unsure if it's the right time. Too much root rot can cause them to die, so be careful not to overwater or underwater regardless of the climate or season you have in your area.