Creating a new garden, in my opinion, is a lot more fun than maintaining an established garden over many years.
Keeping a garden presentable across all seasons of the year requires an eagle eye, considerable commitment of time and energy on the part of the gardener, and constant fine-tuning of design elements.
Gardeners also need back-up to cover those inevitable times when one is ill, busy, or on vacation.
Perennials, annuals, trees, and shrubs require a lot of care when they are first planted in order for them to get acclimatized and their roots well established. Frequent watering is important in the first year for trees and shrubs and in the first month for perennials. Annuals, that bloom continuously from spring through fall, need regular watering and fertilizer to keep them performing well.
Most also need deadheading to keep them flowering. Some, for example wave petunias, have been bred to be self-cleaning, which is easier for the gardener as deadheading religiously is time consuming.
Mulching is also time consuming, but a mulch keeps a garden looking neat, conserves water, and cuts down on weed-seed germination.
Experienced gardeners are usually careful to read the labels on plants they purchase in order to understand their particular needs. Restraint in terms of the number of beds and pots that are planted each year also is a help in preventing the amount of maintenance that is required over time.