Garden - Maintenance

Jan

Grass - remove green shoots as soon as they appear (oops forgot this year!)

February
Foxglove - Prune off winter-damaged leaves
March

Daffodils and Hyacinths - cut off heads as soon as the flowers die

Liatris - divide and move (last chance of frost)

March/April

Hosta - divide and replant
Buddleia - prune

May

Azalea - prune after bloom, cut out whole branches

Hibiscus - new growth will come up in late spring
Foxglove - remove spent flower spikes to promote rebloom.

June/July

Achillea (yarrow) - will fall over if too wet; encourage repeat bloom by deadheading the spent flowers just above the buds of new flowers.

Hydrangea - prune 1/3

Summer

Liatris - remove spike tips to trim away dead flowers 

Heliopsis - remove faded flowers for more blooms (next to Buddleia)
Buddleia - remove dead flowers regularly

Fall

Buddleia - cut to 1" from ground

Foxglove - do not cut back

Rudbeckia - Dead-heading or cutting back faded flowers regularly will encourage the plant to re-bloom later in the season. Seedheads are good for winter interest, if you choose to keep them, and are also a good food for the birds. Rudbeckia self-sows freely, so deadhead if you do not want volunteer seedlings next season.
Echinacea - Grows from roots and seeds

Nov

Roses - prune