General Tasks

  • Support dahlias and trap earwigs.
  • Sow butterfly flower (Schizanthus) and stocks.
  • Plant Madonna lilies, tender cyclamen and arum lily.
  • Pot up house-plant seedlings.
  • Rest hippeastrums and tuberous rooted begonias.
  • Take pelargonium cuttings.
  • Continue deadheading.
  • Cut flowers for indoor display and for drying.

The Flower Garden in Summer

What to do in the flower garden in August

Ensure that tall plants and especially large flowered dahlias, are well staked, as late summer gales are common in August. Even without winds, the weight of the flowers can snap the stems, especially when wet with rain.

Earwigs can prove to be a nuisance in August, especially amongst the dahlias, as they eat the young shoots and leaves at night and may even attack other plants such as delphinium and asters. A traditional method of trapping them is to place a flower pot, filled with straw or grass, upside down on top of a stake near the plants at risk. The earwigs will collect inside the pot, as they hide from the light. Simply remove the pot each morning and dispose of the contents. Then refill with straw or grass and set the trap again for the next evening.

What Flower Seeds to Sow in August

Sow butterfly flower (Schizanthus) and stocks now to give a beautiful house display next spring.

Schizanthus Angel Flowers

What Plants to grow in August

Madonna lilies (Lilium candidum) can be planted this month. It seems an odd time of year to do so, but these lilies begin growing new roots and leaves from late August. Choose a sunny spot and well drained soil. Plant them shallowly under 5cm (2 in) of soil, also add a little lime to the surrounding soil.

If you haven't started your tender cyclamen into growth, do so now.

The rhizomes of arum lily (Zantedeschia aethiopica), can be started off this month, either from newly bought plants, or existing plants that you have been resting through the summer. They need large pots of about 25 cm (10 in) using a soil-based compost. Keep the compost on the dry side until signs of growth appear, then increase watering.

Early flowering tuberous rooted begonias and hippeastrum (Amaryllis) bulbs should now be gradually dried off ready for storage.

Cuttings and Pruning

Pelargonium cuttings can be taken now, so they can be well rooted by the time the cold weather comes. Follow the same method as for cuttings taken in spring. If your pelargoniums are good sized, you should be able to take plenty of cuttings without disfiguring the plants. The plants will respond to this pruning by sending out fresh side-shoots. For details see our section on Propagation by Cuttings.

Keep cutting sweet peas, to fill your house with scent and to keep the flowers coming on the plants.

Start cutting everlasting flowers for drying now. Besides the ever popular honesty (Lunaria annua) and straw flower (Helichrysum), try drying the lovely green bell-like calyces of Ireland (Molucella laevis). If you haven't grown special flowers for drying, try experimenting with what you do have. Hydrangeas dry very well, for example, and you can try drying ferns, flowers belonging to the daisy family, and ornamental grasses.

The flowers or foliage you intend to preserve must be bone dry and in peak condition to start with. Hang them upside down, either singly or in bunches, in a dark, airy place. Do not make the bunches too big, or the air won't be able to circulate freely.

Next Page >> Taking care of the Lawn in August >>

Plants for August

Herbaceous perennials in flower this month:

acanthus spikes



Achillea (Yarrow)

hollyhock red flowers

Althaea (hollyhock)

Alstroemeria flowers


Anemone japonica

Anemone japonica

aster flowers purple

Aster (Michaelmas daisy)

Astilbe flower


Campanula flower

Campanula (bell flowers)

Chrysanthemum flowers orange





Helianthus (sunflower)

Hemerocallis flower

Hemerocallis (day lily)

hosta white flowers

Hosta (plantain lily)

red hot poker

Kniphofia (red hot poker)


Lysimachia (loosestrife)

Osteospermum flowers


Penstemon flower


phlox flower



Persicaria (knotweed)


Scabiosa (scabious)

Rodgersia pink flower


rudbeckia purple cone flower

Rudbeckia (coneflower)

salvia blue flowers

Salvia (hardy)



solidago goldenrod

Solidago (golden rod)

Tradescantia flower purple

Tradescantia (spiderwort)

Next Page >> Taking care of the Lawn in August >>