Everyone does this wrong. Here’s the right way to grow rhododendron from cuttings

Mist the cuttings regularly to keep the foliage hydrated, but avoid over-saturating the soil. Place the cuttings in a location where they receive bright, indirect light. Direct sunlight can scorch the leaves, while too little light can slow down the rooting process.
8. Temperature and Bottom Heat: The Secret Weapon for Fast Rooting
Maintaining the right temperature is key to successful rooting. Rhododendron cuttings root best when the air temperature is between 60°F and 75°F, with the soil temperature slightly warmer. Using a heat mat to provide bottom heat can significantly speed up the rooting process by keeping the soil at a consistent temperature of around 70°F.
Bottom heat encourages faster root development by stimulating enzyme activity and cell division at the base of the cutting, which is critical for successful rooting.
9. Watering Rhododendron Cuttings Without Rotting Them
Watering is a delicate balance when it comes to rooting cuttings. The soil should be kept moist but not waterlogged. Overwatering can lead to rot, while underwatering can cause the cuttings to dry out and fail.
Check the moisture level regularly by inserting your finger into the soil. If the top inch feels dry, it’s time to water. Use a spray bottle or gentle watering can to add moisture, being careful not to disturb the cuttings or compact the soil.
10. How to Check for Roots and Pot On Without Setbacks
After several weeks to a few months, depending on the variety and conditions, check for root development by gently tugging on the cuttings. Resistance indicates that roots have formed. Alternatively, you can carefully remove a cutting from the pot to inspect for root growth.
Once roots are well-established, pot the cuttings into individual containers using a good quality potting mix. This transition should be done with care to avoid damaging the delicate new roots. Water them in and keep them in a sheltered location while they adjust to their new pots.
11. Hardening Off and First-Year Care for Strong, Garden-Ready Plants
Hardening off is a critical step to prepare the rooted cuttings for life outside the controlled environment. Gradually acclimate the young plants to outdoor conditions by exposing them to increasing amounts of sunlight and airflow over a period of 7 to 10 days.
During the first year, continue to monitor water levels and protect the young plants from extreme weather conditions. Fertilize sparingly with a balanced, slow-release fertilizer to encourage strong growth without over-stimulating the young plants. With proper care, these rhododendrons will be ready to plant in their permanent garden locations by the following year.