Liquid feed once plants show signs of growth.

If the weather is warm and sunny, you may need to start damping down the floor of the greenhouse, splashing water over it to increase humidity levels in the whole glasshouse.

On warm days, open vents and doors of greenhouses to reduce humidity and help prevent disease.

Keep alpine houses well ventilated.

Apply a light covering of shade paint on greenhouse panes, to prevent plants becoming scorched by bright sunshine. Alternatively, a sheet of newspaper or some shade netting from the garden centre work fine as temporary shading for seedlings and young plants.

Pot up houseplants showing signs of being root-bound or top dress large containers with fresh compost.

Clean shiny-leaved plants with a damp cloth and spiky plants with a soft brush.

Brush up fallen compost and debris, and pick off dead leaves from plants. This will help prevent pests and disease spreading.

Maintain a minimum of 5°C to prevent Fuchsia, Pelargonium and other tender plants being killed by the cold. Higher temperatures (at least 12°C/54°F) will be needed for tropical plants.

Begin feeding citrus plants with a proprietary citrus feed, or using a high-nitrogen feed with added trace elements.

Greenhouse bulbs that have finished flowering (e.g. freesias and Lachenalia) can now be fed weekly with high potassium feed (such as tomato fertiliser), to build up the bulbs before resting them over the summer. Reduce feeding and watering as the foliage starts to die back, and then lay the pots on their sides under the greenhouse bench until next autumn.

Pot up any Begonia, Gloxinia and Achimenes plants that you started off earlier in the spring and are now large enough to re-pot.

Cool conditions and regular watering will help keep potted indoor azaleas looking good for longer. Remember to water azaleas with rainwater collected in a rain butt, not with tap water.

Deadhead Hippeastrum (amaryllis), leaving the flower stalk(s) to die down naturally. Keep feeding and watering, and you may be treated to further flowers in August, as well as the normal blooms next winter. Alternatively, feed only for a few weeks (to build up the bulb) and then reduce the watering, let the leaves die back, and allow the plants to dry out completely. The bulbs can be ‘rested’ like this under the greenhouse bench or in a cupboard if they are houseplants), to be brought out in late summer or autumn, for flowering the following winter.

Rest pot cyclamen that flowered over the winter, reducing watering until the foliage starts to die down. The pots can be placed under the greenhouse bench (or in cupboard if they are houseplants), to be started back into growth in late summer.

Don’t forget to prick out seedlings before they get too crowded, and then to pot them on as individual transplants as soon as they are large enough.

Take leaf cuttings of Streptocarpus plants.

Hydrangeas and fuchsias can be propagated from softwood stem tip cuttings.

Try growing on plug plants in your glasshouse. They are a relatively cheap source of large numbers of plants, and avoid the need for propagation facilities and time-consuming pricking out.

Don’t forget to give glasshouse plants more space as they put on new growth. This will help to prevent disease, and to contain early pest infestations.

In warmer areas, you can probably put away the glasshouse heater. But remember that temperatures can still drop at night. Last year we had frosts until late May in southern England. Seedlings in particular object to wide temperature fluctuations. A heated propagator could be a cost effective answer if your glasshouse is otherwise full of hardy mature plants.

In reliably mild areas you can start to harden off half-hardy bedding plants that were started off early under cover. By placing them outside for a short period only, at the warmest time of day, and then gradually increasing the length of time until they are outside permanently, you can avoid the shock that they otherwise experience when moved outside suddenly.

Clear leaves and twigs from guttering on greenhouses and sheds.

You could use spare space in the glasshouse to warm up grow-bags ready for planting.

Pest & disease watch

Brush up fallen compost and debris, and pick off dead leaves from plants. This will help prevent pests and disease spreading.

Damping off of seedlings can be a problem with sowings under glass. Clean equipment and, where necessary, use of fungicides such as Bio Cheshunt Compound can help to control this problem.

Insects start to emerge as temperatures increase. A mild spring can see pest problems developing earlier than usual.