Evergreen Trees and Shrubs

By Lorraine Spooner

The term ‘evergreen’ can be misleading. All leaves will eventually be discarded when they are shaded out by emerging new growth, but this is a gradual process of renewal and is nature’s efficient way of keeping the tree in good health.

The purpose of a leaf is to capture sunlight, which is converted into food through photosynthesis.  When access to sunlight is restricted, the ability to carry out this important function is reduced, so the leaf then yellows and falls. Young leaves can then begin to mature, taking advantage of increased light levels, and so the whole cycle begins again.

Evergreen Trees and Shrubs

The amount of leaf loss can vary between species and is dependent on a number of prevailing factors. This affects the amount of shedding, and sometimes plants will lose more leaves than nature intended.  A lack of water, nutrients or compacted soil with poor drainage can be responsible for unnatural levels of foliage falling, which leads on to my next topic for this week:


With another summer of high temperatures on the forecast, now is the time to take action to protect your plants from extreme environmental changes.  Plants in good health are far better equipped to withstand the rigours of drought, pests and diseases.

  • Watering – carry out our squeeze soil test (see information below) to assess the water requirements of the soil around your plants. Take the recommended remedial action immediately to ensure adequate water is reaching the roots, especially at the outer perimeter of the plant’s canopy. This is where the fibrous roots will be growing, which are responsible for the take up of moisture
Evergreen Trees and Shrubs
  • After watering, cover the soil with a thick mulch (10cm minimum) of fine bark or compost to trap the moisture and suppress weed growth. Horticultural grit is very effective in containers if there is insufficient depth available for a thick layer of mulch
  • Consider installing a trickle irrigation system if practical – this ‘leaky hose’ can be buried beneath the mulch and connected via solid pipe to your nearest tap outlet. Alternatively, new trees can be accommodated at planting time by wrapping a metre length of watering tube around the root ball before backfilling. Leaving the top just proud of the soil surface, your hosepipe is then inserted into the top of the watering tube, providing water to penetrate at root level where it is most needed. These irrigation solutions are available at the Plant Centre, so please ask for advice on which components may be required to accommodate your different garden areas
  • Assess your plants for any damage caused by wind – broken or damaged branches need to be pruned back to prevent diseases taking hold through wounds, which would weaken the plant and attract pests
  • Check stakes, ties and plant supports regularly, adjusting where necessary as the girth of trees increases
  • Also check guards – if these were used at the time of planting to protect against rabbits, deer etc., ensure that they are not too tight as they can strangle plants if left unchecked. Spiral guards should be removed after 4-6 years and other stakes should be removed after three seasons
  • Wind movement can loosen the soil around roots making them more susceptible to drying out. This is especially important on newly planted trees and shrubs as they would not have had sufficient time to establish their root system into the surrounding soil.  Roses and other shallow rooted plants (such as fruit trees) are particularly susceptible.  Firm the roots back in (taking care not to compact the soil), water and top dress with fresh compost
  • Use organic methods of protection from pests such as slugs, which are particularly prevalent in warm humid weather. Be vigilant: certain pests like aphids can attack and cause severe damage to a plant very quickly.  If you garden organically, these can be removed by hand or hosed off to decrease severe infestations, but bear in mind that birds will be feeding their fledglings at this time of year and they love aphids!
Evergreen Trees and Shrubs
  • Keep on top of weeding – weeds compete with plants for water and nutrients. A newly planted tree should have a planting circle a metre wide and kept free of any other plants, especially turf
  • To maintain top condition through the growing season, or to provide a boost to an ailing plant, apply an organic seaweed solution, either as a root drench or as a foliar feed. The Maxicrop range is sold in our Plant Centre shop and can be used all around the garden, even on the lawn

Preventative action taken now will repay you with a garden full of strong, healthy plants in subsequent seasons.

Do come and speak to one of our experts, or email me (Lorraine@nicholsonsgb.com.sites.public-internet.co.uk) if you would like further clarification on any of the above points.

Evergreen Trees and Shrubs