Garden Blog | April
Here we are in April. As days are now longer than nights, and the sun reaches ever higher into the sky each and every day, our gardens are responding to this stimulus by growing like billy-o. Seasonal flowering plants, from towering magnolias to tiny primroses, and everything in between, really are filled with the joys of spring.
Another consequence of the lengthening days and higher sun is the potential for overheating in glasshouses. Here’s the science bit…Glasshouses are warmer than the great outdoors because all that sunlight coming in through the clear glass turns into heat when it hits solid surfaces, including plants, within the glasshouse. This heat is then radiated back into the air from the solid surfaces. The heat emitted has a different wavelength to light, so while light energy can easily pass through the glass, heat energy takes longer to escape. The trapped heat energy warms the air inside the glasshouse. With the glasshouse being relatively air tight, trapped warm air raises the entire building’s temperature. Glasshouses are, therefore, vulnerable to overheating from spring until autumn. Without protection from excessive heat and light, and as a result having a dry atmosphere, many ornamental plants will suffer. However, with sufficient air circulation, humidity, and shading, plants can tolerate summer glasshouse temperatures in the same way that they survive in the tropics and subtropics where many conservatory plants originate.
By ventilating your glasshouse, shading it, and providing adequate water and feed for your plants within, you will keep happy plants all summer long. Ventilating your glasshouse is the first step to a good microclimate, and it’s as simple as opening doors and roof vents when temperatures have reached the desired high, allowing a through-flow of air. On its own though, this isn’t likely to be enough, this is where shading comes in. Shading reduces the light that passes through the glasshouse glazing, therefore reducing the heat that is radiated back into the air. Shading can be provided in a number of ways; either by blinds, netting, or shading paints. All are effective, but vary in cost, convenience, and aesthetic appeal. Here at Deene Park, we use shading paint as it is cost and time efficient, requires no storage over winter like netting, and no maintenance like blinds. Whatever route you chose to go down, glasshouse shading is well worth using.
It’s was only a week ago that we sowed seed under cover, and already they are bursting into life. Each year we grow annuals for use in pots and urns, and as fillers for the borders, together with a number of hardy perennials, to form part of our permanent display. This is a very inexpensive way to fill the garden with colour, and as long as you follow the instructions on the seed packet, you’ll be rewarded with masses of new plants.
You may remember that in September’s blog we were taking masses of cuttings of half-hardy perennials to use in both the house and garden this year…well they are coming on in leaps and bounds. Many are now housed in our polytunnel, which is simply kept frost free, ensuring that the plants within are tough enough to be unharmed by cooler temperatures when they are planted out towards the end of May. Our exotic Nigerian black banana, and angel trumpet brugmansias are housed in our warmer glasshouse, and are also raring to go for their summer stint in our pots and urns.
All-in-all, things really are racing away in the garden right now. Happy gardening…