Science in Glenveagh Gardens

The Weather at Glenveagh

There are 2 weather stations at Glenveagh, one in the walled garden and the other 2 miles from the castle near the park entrance. We take various weather readings daily in the Castle Garden. These records help the gardeners keep track of weather conditions, soil temperatures, and frost occurrences and compare weather conditions from year to year. It helps us decide for example when the soil temperature is right for planting.

The readings are posted to Met Eireann’s Head Office in Glasnevin, Dublin every month from all weather stations across Ireland so that they can keep up to date weather records for the entire country.

At this stage we have discovered that May is on average our driest month and December is the wettest. We can also check for example, the coldest day in the past 10 years.

One of the things we have noticed is that the rainfall readings are different at both Glenveagh weather stations even though they are only 2 miles apart! The Castle Garden station records slightly higher rainfall.

How we carry out our Weather Readings:

There are 6 different temperature readings and a rainfall reading taken every day. These are:

1 & 2. Dry bulb and wet bulb temperature, to determine humidity.
3 & 4. The maximum and minimum air temperature (over the past 24hours).

These first 4 readings are taken from thermometers housed within a Stevenson Screen – a white box with louvered sides 1m above ground level.

5. Grass temperature – at ground level.
6. Soil temperature, at a depth of 50mm.

7. Rainfall measured in mm, from the rain gauge.

More Information

We entered all these readings ranging from January 1997 to December 2007 onto a spreadsheet and found that the highest temperature was 29.3o C on 19th July 2006 and the lowest temperature of -5.2oC on 3rd January 2003.

For the rainfall reading, a rain gauge is used. This consists of a container, sunk into the ground, with a bottle inside it, and a funnel to collect the rain, hail or snow and channel it into the bottle. At 9am every day the rainwater is poured into a special measuring cylinder and a reading taken.

We calculated the total rainfall for each month as well as the total rainfall for each year. From this, we found that the total average yearly rainfall for 1997 to 2007 was 2034.5mm.

We also found that the wettest month was December 1999 with 465.1mm rainfall, and the driest month was July 2005 with 40.1mm.

A comment may also be entered for each day regarding the weather conditions for example, on the 18th December 2001 the diary reads:

Dry bulb 3.1o Grass -3.5o
Wet bulb 3.0o Soil 0.7o
Screen max 7.3o Rainfall 3.4mm
Screen min 0.3o Remarks Cloud, cold, frost

July 2006 had our hottest day in the past 10 years with a maximum air temperature of 29.3oC on the 19th.

December of that year was the wettest month we have had in the past 10 years with a total of 465.1mm rainfall.


What is Phenology?

Phenology is the study of the seasonal timing of life cycle events. At Glenveagh, we observe and take note of the emergence of leaves and flowers on trees and shrubs in spring. In the autumn we note when leaves change colour and when they drop. By making note of these events we are able to follow the changes in the seasons and how they affect the growth of plants. In the light of “global warming” keeping these records will help us understand any changes that are happening in our climate.

International Phenological Gardens

Glenveagh is one of a network of 70 Phenological Gardens around Europe. The idea was first put forward by Schnelle & Volkert at Offenbach, Germany in 1953, that all these gardens should have exactly the same trees and shrubs planted, and observations should be made of the timing of their various life cycle stages. The observations from the different gardens are then compared. In this way it has been discovered that the advance of spring makes its way north and west across Europe at walking speed.

The plants that we grow at Glenveagh are:

  • Larix decidua
  • Picea abies (early)
  • Picea abies (late)
  • Betula pubescens
  • Fagas sylvatica (HAR)
  • Fagas sylvatica (DUD)
  • Populus tremula
  • Prunus avium BOV
  • Quercus robur
  • Robina pseudacacia
  • Sorbus aucuparia
  • Tilia cordata
  • Salix aurita
  • Salix acutifolia
  • Salix smithiana
  • Corylus avellana
  • Syringa vulgaris

At the end of each year, the readings from all the I.P.G.’s are sent to Humboldt University in Berlin where the comparisons are then made.

More Information

This network can be added to at any time by transplanting ‘clones’ (young plants from one of the original phenological gardens) to a new area. By using plants that are ‘related’ to each other and following certain guidelines we can get the readings as accurate as possible for them to be compared.

  1. The land needs to be normal for the area (for example, Glenveagh National Park has the type of land that is all around us in the mountains in Donegal).
  2. It also needs to have typical weather compared to the area around it (for example, it shouldn’t be in a place that gets flooded or doesn’t get enough rain).
  3. There should be a weather station nearby, like we have at the Glenveagh Castle Gardens.
  4. It should have vegetation (plant life) around it as in many protected parks and gardens.

The Phenological Phases

Each I.P.G. has to fill in a form with dates of when each ‘phenological phase’ takes place on each of the different plants. There are 8 of these phases:

  • Beginning of leaf unfolding
  • May shoot
  • Beginning of flowering
  • General flowering
  • St. John’s Sprouts
  • First ripe fruits
  • Autumn colouring
  • Leaf fall


At Glenveagh we have a SEISMOGRAM which measures seismic waves from earthquakes near and far. We have this in conjunction with the Dublin Institute for Advanced Studies, who are researching and studying the earth’s structure and its movement. They have distributed a number of these very sensitive instruments throughout Ireland. Readings can then be taken of any ‘seismic activity’ detected, which can be from earthquakes as far away as South America. A seismogram can detect activity to a depth of several hundred km. The aim of this study is to find out exactly what is going on in the earth’s crust below Ireland and to improve our knowledge of the changes that have taken place and are still taking place.

How to Read a Seismogram

There are 4 readings on the Seismogram:

  1. Origin Time To the nearest 0.1 second that the earthquake happened
  2. Magnitude The strength of the earthquake (Richter Scale). This is based on two different types of seismic waves.
  3. Depth How far down inside the earth the earthquake happened (in Km)
  4. Location Exact geographical co-ordinates measured in Latitude & (Epicentre) Longitude.

The Donegal Earthquake

On the 21st February 2008, one of the largest tremors ever recorded in Ireland took place in Co. Donegal. People in the Ramelton area felt this tremor.
This is how the seismogram read:

Origin Time
Magnitude 2.4M
Depth 5.0km
Location 55.137N 7.470W