Planting and tending
In principle, rhododendrons are resilient and long-lived plants, but they do make some demands where their location is concerned. To guarantee a long life and keep them in the best condition possible, it is advisable to take the following to heart.
• A rhododendron grows and flowers best in the so-called semi-shade. Try and find a location which offers both sun and shade.
• A rhododendron makes the following requirements with regard to the soil: The acidity (pH) should be low enough. For a healthy growing plant, a good balance between aeration and water retaining capacities in the soil is very important. All three factors can be positively influenced by mixing in peat dust with the soil.
• The optimum pH value for classical rhododendrons is somewhere between 4.2 and 5.5. For rhododendrons on a lime-tolerant rootstock, the right pH is between 4.5 and 6.5. The pH of the soil can be lowered by mixing in peat dust with the soil in the planting hole before planting. This also increases the level of organic matter in the soil.
• It is advisable to apply a mulch layer of peat dust and/or leaves or pine-needles every year. Do not add compost! Compost increases the pH value and can contain too much salt. Otherwise, it is hardly necessary to add manure or fertilizer.
• A rhododendron has superficial and roaming roots. The root structure is extremely delicate. It is important that the planting hole is large, around three times the size of the circumference of the root ball and about as deep as the root ball is thick. The rhododendron should never be planted deeper than it has been grown in the nursery. The planting hole can be filled up with a mixture of peat dust and earth.
• Rhododendrons thrive when the soil is not overly moist and any excess water can drain away quickly. After planting, they should be irrigated during dry spells in spring and summer. Rule of thumb is: Not too much!
• For the best results, consider nipping out withering flowers after they have finished flowering. This can be easily done by bending the racemes. After flowering, the plants can be pruned, or the new young shots can be headed. By taking these measures, more buds will form and the plant will not waste energy to unnecessary seeding.