July Zone 4

What to do in the garden in July in zone 4

  • Mulch trees  With summer heat setting in, mulch around trees should be refreshed to help the soil retain moisture.  Apply a 2-4” deep layer in a wide circle around the tree, the wider the better.  Do not allow the mulch to contact the trunk.
  • Fertilize the lawn  Your grass can be fertilized about every 6 weeks.  If you are due, apply now before the heat really sets in.  A healthy lawn will survive heat and drought much better than a weak lawn.
  • Plant gladiolas  Early July is your last chance to get gladiolas, mums and dahlias in the ground for fall blooming.
  • Remove spring bulb foliage  If you have not already cut down the foliage from your spring bulbs, they are ready now.  Leaves should be yellow white and withered.
  • Feed annuals  Annuals need regular fertilizing for good bloom production, about every 4 weeks.
  • Cut back iris stalks  When iris blooms have withered, cut the flower stalk to the base.  If you have reblooming iris, this will encourage a second bloom late in the season if fall is warm and long, however the zone 4 growing season is generally not long enough for a second bloom.
  • Trim flowering shrubs  Flowering shrubs that have completed their summer bloom can be trimmed back to improve shape and appearance.  Additional blooming may be encouraged.
  • Raise the blade  Raise the blade on the lawn mower, you should be at about 3” for summer heat.  The growth will be slowing down a bit anyway in the summer heat, and a little longer grass shades the soil better to retain moisture.  Your lawn will look much greener and healthier, and require less sprinkling.
  • Check for slugs  June is sometimes a rainy month and will encourage slugs.  If slugs have eaten holes in the foliage of your shade plants such as hosta, pick out the slugs and dispose of them or apply non-toxic Sluggo.
  • Spray roses for insects  Tea roses, foribunda and grandiflora roses should be treated for insects.  Try organic products such as insecticidal soaps,  Neem Oil and Remedy fungicide.
  • Check for insects  Keep an eye on your plants for insects that may be causing damage.  Do not indiscriminately spray insects, as many are beneficial.  Even those that cause visual damage may not necessarily be harming the plant.  Check with your local garden center or extension service to properly identify and treat for insects.  Routinely spraying them off with a garden hose or applying insecticidal soap is often the best course of action.  Aphids is a common problem.  Although they generally do not do permanent damage, they can inhibit growth and weaken the plant.
  • Check for disease  Keep an eye on your plants for signs of disease such as wilting, leaf drop, and discolored foliage. Check with your local garden center or extension service to properly identify plant disease and treatment.  It is tempting to water and fertilize if a plant appears weak or diseased, but until the problem is identified it is best to withhold both water and fertilizer.  Many diseases are caused by or accelerated by over watering and poor drainage.  Keep watering to a bare minimum until the problem is identified.
  • Weed the gardens  The never ending summer chore.  If you haven’t kept up with weeding, by now they are pretty well established.  Be sure to get all the root when you did, sometimes the tiniest root pieces can grow a whole new weed.  Prevent a big fall weed crop the competes with your garden plants for water and nutrients.
  • Fill the birdbath  Fill shallow birdbaths frequently.  Deep birdbaths can harbor mosquito larvae.
  • Water  July can be hot and dry.  Make sure everything is getting enough water, about an inch per week for most plants and lawn.  Tomatoes must have consistent watering to prevent mis-shapen fruit and blossom end rot.
  • Fertilize vegetables  Fertilize the vegetable gardens every few weeks with a liquid fertilizer, less often with slow release and organic fertilizer.  Most herbs need little or no fertilizer if the soil is well enriched.


  • Check containers and baskets  Container gardens, hanging baskets and window boxes dry out quickly and need frequent watering.  They will also need to be fertilized regularly.
  • Fertilize roses  Hybrid tea roses, grandiflora and floribunda roses, all need to be fertilized about once a month into July.  Timing of applications should correspond to the completion of bloom cycles.  Make sure they are also getting a deep watering each week, about 1 - 1 1/2 inches.
  • Start seeds  Start perennials from seed now and they will be ready for fall transplant to a permanent home.  Planting them in a “nursery” bed or in pots will prevent trampling them accidently.
  • Pinch and deadhead  Annuals and perennials are growing fast now, so pinch them back before them become leggy.  Deadhead spent blooms on perennials finished blooming.  Certain perennials develop interesting seed pods that you may want to leaf for interest or to produce seeds.
  • Evaluate  Make notes in your garden journal frequently.  Record how each plant is doing and the time of year and weather conditions.  Note whether soil seems to dry out too quickly or hold water too long so you can amend the soil next season.  Note areas that are being shaded more by growing trees so you can move perennials as necessary next season.
calendarSharon Dwyer