Summer Gardening Tips

The 4 main components to retaining a beautiful summer garden are:

  • Watering
  • Fertilizing
  • Deadheading
  • Weeding

Water, Water, Water!

Watering is the key to having a lush garden all summer. Hanging baskets and planters need to be watered almost daily.  Once a basket dries out, there is a chance it may not recover as the roots may be irreparably damaged. Flower beds require less frequent watering for they are buffered by a large soil volume that holds a larger store of moisture. Additionally, if the bed is fully planted, the full cover of plant foliage shades the soil and reduces moisture evaporation from the soil surface. Mature, fully planted beds may only need water once a week or less. Raised beds often dry out faster than flat beds and will therefore need to be watered more frequently.

Slow, deep watering is best as it encourages roots to grow deeper into the soil. Try to water just around the roots and under the foliage. Avoid directly wetting the foliage as water droplets can act like a magnifying glass and leave burn spots on the leaves. Using soaker hoses rather than sprinklers saves water since less is lost to evaporation.

It’s best to water in the morning so plants have a chance to dry off during the day. Wet foliage and flowers are prone to contracting diseases. Watering in the heat of the day is inefficient for much of the water evaporates before it can reach the plants.

If you are going on holidays and the forecast is for dry weather, make sure someone comes to water your garden. Also consider moving all of your containers to a shadier spot and putting your hanging baskets in a shallow dish of water to keep them moist.


The 3 ratios that come on any fertilizer package stands for the percentage of N:P:K.

N = nitrogen – fosters lush foliar growth

P = phosphorus – promotes root growth and boosts flower and fruit production

K = potassium – helps overall plant health

Knowing what your plant needs or is lacking will determine what fertilizer to use. If your flowers aren’t flowering well, use a fertilizer with a high P ratio. If they are blooming but look stunted or have pale leaves, use a balanced or high N fertilizer. In mid-summer, fertilize Lilacs, Rhododendrons, and other spring flowering shrubs with a high P fertilizer to help with bud set. These plants set their buds for next year in the summer.

If despite regular fertilization some of your plants look sickly, check your soil acidity. If the soil is too acidic the plants may not be able to absorb the fertilizer, and some lime may need to be added to balance out the pH.

Be aware that fertilizers labeled “organic” simply mean they contain carbon atoms. They can be naturally sourced or chemically made.

Water- Soluble vs. Slow Release Fertilizer

A water-soluble fertilizer is dissolved in water and can give an immediate boost of nutrition to your plants since foliage and roots readily absorb its liquid form. Water-soluble fertilizers are best utilized for blooming annuals and perennials, hanging baskets and containers that require a high feed: use every one or two weeks at half concentration. The downside with water-soluble fertilizers is that they can easily wash out of the soil in a heavy rainfall, necessitating another dressing. This can also be a problem in sandy or well-drained areas where the fertilizer may trickle past the root area. It is also important not to use a water-soluble fertilizer on dry soil for this may burn plant roots.

Slow release fertilizer comes in little pellets that slowly release nutrients over time. Most are heat or moisture activated and can be placed on top of the soil surface or mixed into the soil at time of planting. Slow release fertilizers are suitable for hanging baskets, trees, shrubs and established perennials. It is also a handy way to fertilize hard to reach areas and to feed your plants during a vacation absence. Applying some every three months should be sufficient.

Using a combination of both water-soluble and slow release has proven to be the most effective method of fertilizing.

Deadheading and Pruning

Trim back Pansies and Violas, move them to a cooler spot in the garden and wait for them to re-flower in fall. Or remove them altogether and plant some fresh flowers in their place.

Cut back spring flowering bulbs.

Cut back herbs that are going to seed to continue foliar growth; herbs tend to lose their vigor after setting seed.

Prune fast-growing trees like Maple and Birch in mid-summer as their sap flow decreases in the summer heat. This is favorable since excessive sap exuding from pruning wounds makes the tree vulnerable to disease or pest infestation.

Prune spring flowering shrubs after they finish blooming, but no later than mid-July because they set next year’s flower buds in August. Deadhead Rhododendrons to maintain their shape and size. Cut back some of the long, vigorous shoots on your Wisteria for they can be burdensome for the plant to support. Furthermore, this helps set blooms for the following year.


Mulching helps retain soil moisture. There are various types of mulch to choose from including moss, bark mulch and compost.

Place moss on top of soil in containers. This reduces evaporation of water from the soil surface so that the planters don’t dry out as quickly. The moss cover also prevents water and soil from splashing onto leaves during overhead watering.

Bark mulch keeps weeds down for the first year or two and helps the soil retain its moisture; however, it may be hard to water beds that are bark-mulched. The bark nuggets absorb some of the water being applied instead of allowing it to all flow down to the soil. Water also tends to run off dry bark rather than penetrate into the soil below. Therefore, it is not the most water efficient way to mulch.  Composted bark mulch is a better option because it adds nutrient value to the soil, lets water permeate through and helps smother most weeds. Some may find its darker look more attractive as well.

Compost adds nutrients and helps retain soil moisture, but it can exacerbate weed problems. Manure can be used to mulch though it doesn’t have much nutrient value and looks unattractive spread on top of the soil surface. It is better suited for mixing into the soil to add water-retaining organic matter.

Regardless of the mulch you choose, it must be laid to a depth of at least 4” to smother weed seeds. Anything less and the weeds can just grow through.


It is easier to pull weeds when the soil is moist. Hoe or rake weeds under when they are small and before they bloom. If you can keep on top of perennial weeds by continuously cutting off their foliage, you can eventually kill them by starving their roots.

Pests and Problems  

Never spray for pests in the heat of the day for this can burn the plant foliage and is also ineffectual because many pests hide during the midday heat.

If you find aphids on your plants, try planting fragrant, nectar-rich, bright flowers to attract beneficial insects.  Beneficial insects are natural predators that will feed on aphids and keep their population down. Do not use pesticides unless absolutely necessary otherwise you will kill off the beneficial insects as well as the pests.

Powdery mildew can be a prevalent problem during summer; it shows up as grayish, white-colored mold on leaves and shoots. To keep powdery mildew at bay, prune off any infected parts and spray the plant with Defender.

Brown tips and edges on leaves are symptomatic of leaf scorch. This can be caused by various factors including drought stress, excessive fertilization, and strong winds that dry out foliage.

Wilting arises from either insufficient or excessive watering. Over-watering plants can lead to root rot and then the remaining living roots cannot absorb enough water to keep the plant alive.

Always water the area you plan to mulch well before mulching, and keep mulch away from the base of herbaceous perennials so as not to smother any new growth.

Bedding Annuals, Hanging Baskets and Containers

Water, water, water! Watering is the most important thing to maintaining your annuals through the hot summer months.

Dead head annuals and pinch off faded blooms to encourage continuous flowering. Many annuals will stop blooming if they go to seed. Likewise, shear the dead blooms off small flowering plants like Lobelia, Impatiens and Alyssum when they start to lose their blooming vigor.

If annuals start to fade in the summer heat, try pinching the plant back to encourage new growth.

Fertilize annuals weekly with a water-soluble fertilizer at a half rate.

If any plant doesn’t perform well where it is planted, try moving it to a different location.

Leave adequate space between low-growing bedding plants like Begonias and Impatiens to avoid rotting problems.

Some annuals are high maintenance and require a lot of deadheading, fertilizing, etc. If you don’t have the time to properly maintain them, try planting something else.

Make sure your containers have adequate drainage. If your planted plastic containers are not draining sufficiently, try drilling extra holes on the side of the container an inch or so above the bottom. For new containers just being planted up, first fill the bottom with rocks or styrofoam peanuts and put in a layer of fabric to keep the soil layer separate from the drainage layer.


Pinch back perennial Asters and Chrysanthemums 2 or 3 times between June to mid-July. This will give you a bushy plant that blooms in September instead of one that stretches to 4’ tall and blooms in August.

Cut back early flowering, fast growing perennials such as Geranium, Spiderwort, Lady’s Mantle, Iris and Daylily that start looking shabby by mid summer to generate fresh foliar growth and perhaps even prompt a second blooming.

In late summer, dig up and divide your Irises and throw out dried up or rotten corms.

Tall perennials should be staked before they reach their full size. Use numerous stakes around the plant to provide equal support on all sides.

Summer Planting

You can plant in the summer but you must be diligent in watering. Water the plant before transplanting, water the hole it’s being placed into and water after planting.

If a plant has dried out that means some of its roots have too; try cutting the plant back a bit so that the remaining root system has less work to try and revive the plant.

During summer, many flowering houseplants can be planted outside. Candidates include Gerberas, Reiger Begonias, forced Hydrangeas, Calla Lilies and Elephant Ears.

Drought Resistant Plants

To reduce water usage in your garden, try planting drought resistant plants. Many different types of beautiful, flowering plants are drought resistant and can survive the summer heat with minimal watering once they are well established. Also, plants with small or gray, hairy leaves generally require less water.

Place drought tolerant plants in places farthest from you water source and consider replacing parts of your lawn that are hard to mow with a patch of drought tolerant plants.

Many native plants are drought tolerant because they are used to our dry summers. Generally, shrubs and perennials take less water then bedding plants.