If you would like to sow seeds in the greenhouse, perhaps for the first time, start with something easy to germinate. A good choice is carnations which can be grown on as annuals in a sunny border. I suggest these because they only need 7C (45F) and they don’t damp off like many other seedlings in cold weather.
If you are new to gardening, damping off disease kills seedlings quickly.They fall over and when you examine the stems it looks as if someone has squeezed them. Prevent this by using clean seed trays, fresh sterilised compost and clean water. Add copper mixture to the water to avoid copper deficiency.
Copper mixture comes in green containers at garden centres. Use it at the initial watering time. Allow the compost to soak up the solution by putting the tray in a container half-filled with it. Wait until the compost's surface glistens before allowing the tray to drain.
At this time of year, heating a greenhouse is expensive so why not invest in an electric plant propagator? It will last years if kept clean. If you have electricity in the greenhouse, just plug it in. If you don’t have electricity buy a cheap plant propagator. If this is seated on a piece of metal with a paraffin heater set up below, this will do the job well.
Returning to the carnations... annual ones do not do well in flower beds.They are not showy enough, but they do have a place in a border. They are always admired in cottage gardens and flower from June to late October here. There are lovely varieties such as Giant Chabaud, one of the best of the mixed colours. It can be relied on to flower well and is brilliant if the soil is chalky. Sprite mixed has smaller flowers in pastel shades with red or pink frilly edges, not often seen in annual carnations.
If you want to grow perpetual carnations which are kept in the greenhouse all the time, they are expensive to buy as plants. There is a perpetual mixture too, but it will take more than a year to get them to bloom in a cold greenhouse. If you can’t find them and you like growing unusual plants from seed, send for a seed catalogue.
Carnation seeds are best sown in John Innes seed compost as it contains a small amount of chalk. Carnations love chalk. Sow seeds evenly. This isn’t hard as the seeds are not tiny and there aren’t many in a packet. Soak the tray in the copper solution until the compost glistens.Put the tray in the propagator and the seed will germinate in three weeks. Watch each day and water with clean water from a watering can with a fine rose so the compost is always moist. Err on the dry side. If in doubt, keep the compost just moistened.
Once the seedlings are big enough to handle, prick out each one into insert cells so each plant makes a strong root. Plant in the garden at the end of April after hardening them off. To do this, leave the plants outdoors for four days bringing them back into the greenhouse at night. Then leave outdoors for four days before planting out in a sunny border. To ensure the plants are sturdy, nip out the tips once side shoots appear.
THIS WEEK'S TOP TIP
Yellow botanical crocus are blooming in sheltered places. To stop them being damaged by sparrows, cut out the shape of a cat lying down. Paint it black with a white patch on the front to make it look realistic and put two marbles where the eyes should be. Place it nearby and sparrows will keep off the blooms.