A charge for admission to Ilnacullin is made by the Office of Public Works on arrival at the island. This charge is quite separate from the fares collected by boat owners. Ilnacullin is renowned for its richness of plant form and colour, changing continuously with the seasons. The vivid colours of Rhododendrons and Azaleas reach their peak during May and June, whilst the hundreds of cultivars of climbing plants, herbaceous perennials and choice shrubs dominate the midsummer period from June to August. Autumn colour, particularly on the magnificent heather bank, is rich during the usually mild early autumn months of September and October.
Winters are mild, and frosts are light and of short duration.
Even for those who are not particularly interested in gardens, Ilnacullin is an attractive place to visit. There are many attractive views of the scenery of the surrounding district from the island. Ilnacullin and its surrounding waters are quite rich in wildlife, the seals which frequent the rocks on the southern shore being of particular interest to many visitors.