9. Roses (Rosa spp.)
Though exquisite to behold and superbly fragrant, all types of rose shrubs are finicky and need lots of pampering. For flawless blooms, you’ll have to ensure the soil is deep, loose, and enriched with compost, properly plan and space your plants so roses receive good air flow, twice weekly waterings and frequent feedings, regular pruning and deadheading (watch those thorns!), as well as the everlasting challenge of preventing black spots and protecting them from aphids, spider mites, and deer.
10. Gardenias (Gardenia jasminoides)
Terribly temperamental, gardenias require a perfect harmony of watering, sunlight, humidity, feeding, pruning, and mulching in order to glimpse those showy white flowers come summer. Neglect just one or two of gardenia’s needs and the whole plant will suffer.
11. Dahlias (Dahlias spp.)
Adding a touch of colorful cheer to the garden, dahlias vary from teeny half inch pom-poms to enormous 10-inch “dinner plates”. Aside from the usual routine of watering and feeding, dahlias are prone to powdery mildew, botrytis blight, viral diseases, and tuber rot. Gardeners will also need to exercise much vigilance when combatting aphids and thrips, often requiring pesticides to be applied every week to avoid infestations. Prolonging blooms means lots of deadheading and as dahlias grow and become massive they will need to be supported by stakes to prevent their succulent stems from snapping in half.