Gardening Notes For August


To me, August is the month that epitomizes summer.  The days remain long, with the daytime chant of the cicadas with the evening chorus of the crickets.  Fortunately, July provided the garden with ample rainfall and even the lawns look amazingly green at months’ end.  August typically has many humid days, but the temperatures are usually in the 80’s, which is good for both the plants and the gardener!  Remember to get outside during the cool of the morning or evening, use sunscreen and continue to take good notes of your endeavors.     

Things to do:

  • Continue to cut the lawn as growth and rainfall permit.  Maintain a higher cutting height of 3”+ to reduce the stress on the turf.
  • The third and fourth weeks of August are the ideal time for reseeding or seeding new turf areas.  The evening dew becomes heavier and helps to ensure proper growth and the warm soils allow proper root development before winter.  Supplemental irrigation will be necessary if rainfall is light.
  • Make certain plantings from this spring as well as trees planted last year continue to receive weekly irrigation during periods without rainfall.  Remember, that for every inch of caliper size (the diameter of the trunk 6” above grade) for a newly installed tree, the tree will require 1 year of additional care and watering. 
  • Many annuals in containers may begin to look tired.   For some, a light pruning along with weekly fertilizing and daily watering will breathe in new life.  For others, it is simply time for replacement.  For autumn, consider Salvia leucantha (Mexican Bush Sage) and Leonotis leonurus (Lion’s Ear) as options to the garden ‘Mum’.
  • Although still 2 months away, at months end you may wish to start taking cuttings of some annuals for rooting, potting and over-wintering for next year’s garden.  If rooting fails, there is still plenty of time to get new cuttings.
  • Gather and save seeds of various non-hybrid annuals for seeding next spring.
  • Bush beans, peas or other crops that have finished producing should be removed, the soil amended with compost, and the area replanted with a crop that will mature within 70 days or by October 15, the first average date for frost in NJ.  A friend of the Gardens, Bob Mellert mentioned that the days to maturity on seed packets should be multiplied by 1.5 to account for the slower growth time with the shortening days as compared to spring.   Suggestions for 2nd crops include:
    Root Crops
    Leaf Crops
    Broccoli Raab
    Mache (Like Lettuce)
    Fennel (bulbing)
    Mesclun Mixes
    Bok Choy
    Salad Greens


  • The length of harvest time for the crops listed above can be extended by erecting low tunnels in October to mitigate any of the earlier frosts.  You may wish to look into making or buying the hoops and the agribon fabric that is used to cover the tunnels.
  • Squash plants may be wilting from squash borer.  If so, discard the plant (best placed in garbage to remove the borer and any eggs) and plant one of the crops mentioned above.
  • Near the end of August, leafy crops such as Arugula, Spinach, and Lettuce can be planted as the evening temperatures consistently drop into the 60’s and upper 50’s. 
  • August is the time to get your orders in for planting Garlic this fall!
  • Resist the urge to vigorously prune shrubs and trees.  Heavy pruning during August and September will result in a vigorous production of new shoots that will not become ‘hardened off’ by the first frost, resulting in not only their death, but potentially the death of the plant!  Removal of broken branches or light pruning/shaping is still healthy for the plant. 
  • Many tree limbs will gradually hang down lower following the flush of new growth.  Removing the lowest tier of branches on a shade or small tree during August often tends to make the Garden look more open and able to ‘breath’ again.  It also allows more light to reach the plants or turf grass beneath the tree. 
  • Late August is an ideal time to plant new perennials, shrubs and evergreens in the garden, as the soil is warm and root growth is rapid!
  • Try to keep up with the weeding, especially as the summer bloomers are starting to set seed.  Remember, if the plant goes to seed, the average life span of a seed is 7 years!
  • Continue to deadhead most perennials, roses and annuals to promote new flowers.  For some, such as Echinacea and Rudbeckia, you may wish to leave the seed heads, since they are a food source for Goldfinches.
  • Cut back the predominantly brown Bearded Iris foliage and inspect for borer damage in the rhizome.  If the clump is large and root bound, lift, divide and replant during August.  The same is true of Peonies, but be careful to leave the growth buds of the Peonies at or near the surface to ensure blossom production in the years to come.  If the buds are planted too deep, the plants will fail to bloom.  The peony foliage will wilt following division, but the plant will be perfectly fine come spring.
  • Bulb orders should be placed for September or October delivery.  If you are interested in any of the autumn blooming Cyclamen, Crocus or Colchicum, this is the time to place your order for a September delivery!