You want fail-safe gardening? Plant bulbs. All the work has been done for you by the grower and everything is packed into a neat little parcel to which you add water and stand well back. Well… almost.
Provided spring-flowering bulbs are planted in decent soil – not too wet and not too dry – and given a generous amount of light, they can usually be relied on to come up year after year. In pots you can use them as annuals if you are so inclined – planting them out in