Your summer house plant jobs

Summer house plant needs

Light

It’s easy to assume that because many house plants come from more exotic climates than the UK they can cope with direct summer sun. In fact, many house plants are plants that in the wild are found growing under the canopy of taller trees where they receive dappled light and are shaded from the midday sun.

Many house plants are also native to countries that are closer to the equator where day length stays the same so there’s a steady amount of light throughout the year. Growing these plants indoors in the UK means adjusting the amount of light they receive at different points in the year. My dragon tree (Dracaena marginata), for instance, spends the winter and spring by south-facing French doors so that it gets a good amount of light, but now that the sun is much stronger I need to move it away from the window otherwise the leaves will develop dry leaf tips and edges.

Frosted windows or a sheer curtain can help diffuse light and are good options for plants that are particularly sensitive, and east- or west-facing windowsills provide the most plant-friendly amount of sunlight at this time of year, with less intense morning or afternoon sun.

While cacti and succulents will love this time of year, they too can suffer leaf scorch on a baking hot windowsill, so move them a little bit away from the glass.

Water

House plants will need watering more frequently in summer but there will be variation across your plants, as those in warmer rooms will dry out more quickly than those in cooler, shadier spots. It’s tempting to water all your plants once a week, as this is easier to manage, but this approach makes it really easy to overwater at this time of year. It’s much better to treat each plant individually by checking whether they need watering first by pushing your finger into the compost a couple of inches to check if the compost has dried out.

What you do about watering when you go away on holiday is probably the biggest summer house plant care dilemma. Most house plants will be fine for a week if they’re given a thorough soaking before you go away, but it’s a good idea to move them to a cool, shady room, which will mean they won’t dry out as quickly. For two-week holidays you’ll need to come up with a plan to provide sufficient moisture while you’re away. Options include self-watering planters that have a water reservoir at the base; placing pots in a bath or sink on top of water-soaked towels; sitting the pots on a tray with a layer of capillary matting (these are available for greenhouse suppliers); or using a drip irrigation system – this could be a simple nozzle attached to the top of a water bottle.

If you’re going away for longer than two weeks it’s best to ask a trusted friend or neighbour, preferably one that has a few of their own house plants as they’ll know what they’re doing, to pop round once a week to give them a water. I’m lucky to have a utility room, so I move all the house plants into there to make it easier for my in-laws to do the watering and I’ll attach a note to any plants that might also need misting or that need watering from below.

• Holiday care for house plants

Humidity

Standing plants on pebble trays boosts the humidity levels around them, but the water in the trays will evaporate more quickly at this time of year so they will need topping up more frequently.

Grouping plants together to create a microclimate is a good way to maintain humid air around house plants, and misting can help plants that are flagging in the heat. However, don’t mist plants with furry, hairy leaves as moisture sitting on the leaves can cause permanent damage. Succulents and cacti, native to desert areas, are happy with dry air so there’s no need to provide them with extra humidity.

Food

Now that they’re in full growth, most house plants will benefit from a monthly feed during the summer months. Put the liquid fertiliser in a watering can and dilute as per the instructions on the bottle. Some plants, such as orchids, cacti and succulents, require a specific fertiliser, rather than just a general house plant feed, as they have different nutrient requirements. If it’s very hot, postpone feeding until it cools down as plants will be stressed by the heat and will either not be able to absorb the nutrients or the fertiliser could make the stress symptoms worse.

Heating

There shouldn’t be any need to have the central heating on over the coming months, and most rooms in the house should be a steady temperature between 18–24C, however, heat waves can make our homes intolerable for both us and our plants, and with climate change, periods of extreme heat are becoming more common. High temperatures mean plants transpire more quickly, losing water through the leaves to keep themselves cool, and if a plant can’t match the loss of water with the uptake of more water then it will wilt and ultimately die.

South-facing rooms will be the warmest in a house, so it’s a good idea to relocate plants during periods of intense heat to a cooler spot in the house. It’s also worth considering that heat rises, so upstairs rooms, even those that face north, tend to become hot from late afternoon until the early hours of the morning.

If you have an air conditioning unit or a fan move house plants out of the way as the cool air may damage the foliage or cause a cold shock for the plant.

Pest and disease problems

With windows and doors open more frequently during the summer months, the chances of pesky pests flying in and taking up residence on your beloved house plants is much higher. Last summer I found my Streptocarpus, which was near some French doors, was covered in aphids. Aphids in particular can be tricky to see as they are often camouflaged against the plant, so it’s a good idea to get into the habit of checking plants so that you can spot a problem as quickly as possible. A good trick to see if there are any pests and how big the problem is, is to pop the plant pot on a sheet of white paper and tap and brush the leaves so that any pests fall onto the paper.

Fungus gnats, are tiny flies that don’t harm established plants, but because they multiply rapidly they can become a nuisance for us when swarms of them develop indoors. They thrive in damp compost so they’re often a sign you’re overwatering. To stop them becoming a problem let the compost dry out between waterings, use a special house plant compost when repotting and mulch the surface of the compost (try Shell on Earth, a by-product of the shellfish industry). To control infestations, use sticky fly tape placed near the plants or grow a carnivorous, insect-eating plant nearby.

Plant holiday

Moving house plants outdoors during the summer months can give them a reviving change of scenery with plenty of natural light, fresh air and humidity. Not all house plants are suited to this change though, and it needs to be reliably warm with no sudden drops in the night-time temperature before you attempt to move any plants outside. The timing will depend on where you live but from mid- to late June it should be sufficiently mild. Make sure you acclimatise the plants gradually, introducing them to the outdoors for a few hours each day at first. It’s also crucial to bring them back indoors before the night-time temperature drops below 10C in late August to early September.

For lush-leaved plants, choose a sheltered spot that’s shaded – these are generally plants that grow in the dappled shade of rainforest trees. Tender succulents such as echeveria and aeoniums will be happy in a sunny spot, but they will need to be gradually introduced to the stronger light otherwise the leaves can scorch.

House plants that can be moved outdoors include: alocasia, Aspidistra, Monstera, Chlorophytum (spider plants).

Thrifty tip

There’s no need to buy a plant mister, simply recycle an empty cleaning spray bottle, but make sure you rinse the bottle, the spray tube and nozzle really well before you use it to make sure all traces of the cleaner have been washed away. 

Seasonal stars

Begonia rex

Begonia rex and its varied range of cultivars aren’t everyone’s cup of tea, but I love them for their fabulously bold, textural leaves, some with colourful veining or dramatic spirals, others with marbling or spots in silver, pink, red or different shades of green.

Generally it prefers humid conditions, but the hairy leaves mean misting isn’t a good idea, so instead position it in a humid room such as a kitchen or bathroom, or place the pot on a pebble tray. In the wild, the species is a ground cover plant growing in the shade of trees. I keep mine in a corner near a window so that there’s plenty of light but the light isn’t directly hitting the plant.

It prefers reliably moist but not soggy soil, so water then allow the pot to drain and don’t water again until the surface of the compost has dried out. It’s best to use rainwater if you live in a hard water area as the minerals in the tap water can damage the leaves. It likes a steady temperature with not much difference between day and night so try to avoid temperature fluctuations which will stress the plant. Feed every two to four weeks.

Ponytail palm

Beaucarnea recurvata AGM, or the ponytail palm, is a really striking plant that has a distinctive swollen, pale grey stem with a wrinkled texture that resembles an elephant’s foot, and on top of this sits a topknot of long, slender, curving leaves. It isn’t actually a palm, and is more closely related to a yucca. The swollen stem is an adaptation that allows it to survive in the arid climate of its native Mexico.

Allow the compost to dry out before watering again, and feed once a month with a cacti/succulent fertiliser. Because it’s adapted to an arid climate it’s happy in low humidity situations, in bright but indirect light, so it’s ideal for a table or shelf set back from a south- or west-facing window. It’s a slow-growing plant, which is great because you won’t need to repot it every year, but this does mean if you want a statement plant it’s worth buying a good-sized specimen.

Kentia palm

Howea forsteriana, also known as the kentia palm, is an elegant plant which gives a room a real tropical vibe with its upright stands of gently arching, dark green leaves. It can reach around 2-3 metres but it’s very slow-growing, so bear this in mind when choosing your plant.

Harsh sun will scorch the leaves so it’s best suited to a room with east- or west-facing windows, and extra humidity will keep the leaves looking lovely and lush. I think it makes a wonderful bathroom plant if you have the space. Allow the surface of the compost to dry out before you water again and apply a dilute plant feed every 6 weeks between April and August.

Haworthia 'Zebrina'

Haworthia ‘Zebrina’ is a cute little succulent plant from South Africa, which was one of the first house plants I ever bought. It’s similar to an aloe with a compact clump of pointed, fleshy leaves, but these have raised white nodules forming horizontal, stripe-like patterns which give it a unique appearance. I love it because it’s striking but also really low maintenance, and it’s really slow-growing, making it perfect for small windowsills.

Succulents have adapted to grow in harsh environments, but some such as haworthias can suffer leaf scorch if exposed to intense midday sunlight in summer – I grow mine on an east-facing windowsill. It will rot if over-watered or left in soggy compost so wait until the compost has almost dried out before watering, and when repotting use a specialist succulent compost or add perlite to a house plant compost to improve the drainage. Feed with a cactus fertiliser once a month during the summer.

Growing Greener

A cache pot is the attractive container that is used to cover the less pleasing to the eye plastic pot your house plant will have come in when you bought it. While the plastic pots have drainage holes so that the plant doesn’t sit in wet compost and rot, the cache pot should be watertight to prevent any water leaking onto your carpet or furniture.

There are so many beautiful cache pots to choose from, but some have better sustainability credentials than others. Rather than buying new giving an old pot from your local charity shop or flea market a new lease of life is a good option, or seek out containers that are made from recycled plastic or sustainable materials such as bamboo that can be put on the compost heap at the end of their life.