By Debby Looney, gardening expert

I was sitting in the dining room looking out at the garden through sheets of rain, when something caught my eye; a dead plant.

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I shifted my focus, looked around me, and observed quite a few plants close to the point of no return! Indoor plants are easy to forget about, especially when the weather is fine. It is hard to believe but several spider plants, an orchid and a Saintpaulia ended up on a certain compost heap this week.

Houseplants do not need a huge amount of care during the summer months, but there are a few things we must not forget! For example, the most obvious is watering. This is the main growing season for houseplants, so watering is essential as is adding some fertiliser. I use specific feeds for my plants, as the balance of nutrients needed can vary hugely depending on the type. As you can imagine, a large, leafy plant will have different requirements to, say, a cactus, or a gerbera. Most plants prefer to dry out slightly between watering, though not as much as I had let them dry out.

Most indoor plants prefer to be out of full sun as they scorch easily. In particular, leafy plants are susceptible to this. Cacti and succulents are ideal for south facing windows during the summer months. Move any leafy plants to a spot away from south facing windows where they can enjoy a more stable temperature and a slightly shaded light.

Often when plants are under stress, both indoors or outdoors, they become prone to disease, a bit like ourselves. For example, plants which dry out frequently are a prime target for whitefly. They often go unnoticed until there is an infestation, at which point you will see woolly cocoon like clusters, as well as clouds of tiny white flies. Blackfly and greenfly are also common pests indoors. The best course of action, after prevention, is to spray the plant at regular intervals with a pesticide. As it is indoors, I would strongly recommend the use of organic spray, or even soapy water. Alternatively, use a pesticide which can be watered onto the soil, such as ‘bugclear ultra’, as this will have a systemic effect.

This time of year is also suitable for repotting your houseplants, if not done in spring, as they will still get a few months of benefit and strong growth. I mix my own compost as I generally have quite a few to repot. I mix four parts good quality compost, one part sharp sand, one part perlite and one part vermiculite by volume. When repotting cacti and succulents I reduce the compost to two parts, and when repotting orchids, I substitute the vermiculite and perlite with two parts fine bark mulch. I never use homemade compost, as I find there are a lot of insects and ‘other creatures' in it which is fine used outdoors, but I don’t want to invite too much wildlife inside! It is possible to sterilise homemade compost by steaming it, but this is quite an operation, one which I have never undertaken. Alternatively, there are specialist composts available for every type of houseplant. When repotting, use a pot which is about two sizes bigger, unless the plant is a very vigorous one.