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A Hartley Botanic Victorian Chelsea Glasshouse in the summer



Summer Greenhouse Gardening Advice from Hartley Botanic





The summer is a time when the garden comes alive. Many of our most beautiful plants are in full bloom at this time, and our gardens are bursting with life, color, and vigor. However, as well as its abundance, high summer also presents a unique set of challenges for the gardener – especially at a time when extreme heatwaves often take the place of summer temperatures thanks to global warming. Heritage Glasshouse manufacturer Hartley Botanic has provided some useful advice for Greenhouse gardeners this summer, to help keep their Greenhouse growing at its best. Insight has been taken from Hartley Botanic’s online magazine, which provides a wealth of knowledge and inspiration. Visit:

Watering 101


During the peak of summer, it is important to keep an eye on watering and the condition of your plants. Maintain a regular regime of feeding and watering with tepid water. Find out if your containerized plants need watering by sticking your finger into the surface of the potting mix, if your finger is free of particles when you pull it out then the plant needs watering. It’s also helpful to learn how to judge this by the weight of the pot with wet and dry potting mix. When watering, give plants a thorough soak; a light sprinkle will only encourage roots to the surface where they are more susceptible to drought.


Water plants in the evening, poured around the roots, not over the leaves, and check your containers at least once a day and water even if it has rained. Water according to the type of plant – lavenders, from a Mediterranean climate have a low demand for water but bananas are watered copiously as they lose water through their massive leaves. Putting the ‘right plant in the right place’ helps, too, lavender, cistus, cotton lavender, and plants from Mediterranean climates thrive on sandy soils and will only need watering until established.

Don’t water established plants unless they are showing signs of stress and if possible, recycle grey water from the bath but not on edible crops, and don’t use too much bubble bath, either! Mulching pots with mini bark or gravel will keep weeds down and conserve moisture, too. There are lots of practical ways you can save water. You can also help maintain humidity in your Greenhouse by damping down the floor.


All about Greenhouse shade


When it comes to summer, it is not only lack of water that will cause plants to fail. When it is extremely hot, there is a potent combination of plants not being able to suck water up fast enough and the fierce intensity of the sun magnified by glass. It is often too much for plants, and too much for the gardener themselves! There are different ways to shade your Greenhouse, whether you choose convenient roller blinds or a completely natural DIY solution.

When purchasing a Greenhouse it is sensible to consider including internal blinds as an extra accessory to have installed if you do have the budget. Although expensive, they provide convenient shade in the summer months. Hartley Botanic offers roller shades, in a choice of green or white colours, to fit on its Glasshouses and Greenhouses. These are specifically designed to follow the shape of your Greenhouse and will protect your precious plants from damage caused by the sun and help regulate internal temperatures. Motorised systems with sensors enabled by remote control can also make your life even easier, allowing you to operate your roller shades at the touch of a button! The only consideration with roller shades is their location as they could interrupt taller plants such as climbers or vines.

For a completely eco-conscious DIY solution, which can also be fed back into your garden as mulch or compost, is to create shading yourself using cuttings of plants such as bracken, rosebay willowherb (Chamaenerion angustifolium), or other tall-stemmed flattish branches of willow or hazel. Simply lay them over your Greenhouse glass and you have instant, natural shade. If it is not too windy, you can even use plants with huge leaves, such as Giant rhubarb (Gunnera manicata,) which has leaves up to 2m across, or if you have a Greenhouse with a low pitch, grass mowings. Once you have finished with ‘nature’s shading,’ you can then set it to work as mulch, compost material or food for your soil.

Essential jobs for the summer months.

Check plants regularly for signs of whitefly, leafhopper, Glasshouse red spider mite, mealybugs, and scale insects, and treat them with biological controls or environmentally friendly sprays. Keep the Glasshouse free of fallen leaves, flowers, and other plant debris to prevent the spread of diseases.

Remove the side shoots from tomatoes as early as possible. Tie in and pinch out the main stems of indeterminate tomato plants once they reach the top of the support, so all of the energies are channelled into ripening of existing tomatoes.


Harvest crops regularly and train cucumbers and melons onto nets and frames; repot chillies, bell peppers and aubergines until they are in 9inch pots of peat substitute potting mix. Tie sweet peppers and aubergines to supporting canes if needed.


The following can be sown in July: basil, calabrese, Chinese cabbage, winter purslane, (Claytonia), chervil, coriander and dill, French beans (climbing and dwarf,) lettuce, Florence fennel, oriental greens like pak choi, parsley, chard, endive, chicory, beetroot.


Feed citrus with specialist food and continue training climbing plants like Gloriosa superba ‘Rothschildiana’ in a spiral around a tripod of canes, tying in as needed. Keep the pot at the back of the Greenhouse away from the doorway where humidity is higher.


If temperatures are unseasonally low, ventilate using the windows rather than opening the door which causes a draught.

From mid-July you can take semi-ripe cuttings from shrubs like ‘Star Jasmine’, Camellia, Ceanothus, Choisya, Cistus, Convolvulus cneorum, Fatsia, Mahonia and Viburnum. Cuttings taken in summer, rarely need a heated propagator. Keep the potting mix moist until they are well rooted and shade them from sunshine in hot weather.  Remove any dead or diseased cuttings and leaves that fall. Once the cuttings have rooted, they will need ‘hardening off’ for two to three weeks before potting on or planting out.



Hartley Botanic was founded in 1938 by brothers Vincent (RHS fellow) and Norman Hartley following their ground-breaking aluminium Greenhouse design, the first time (to our knowledge) aluminium had been used in Greenhouse construction and marking a huge improvement on its wood and wrought iron Victorian forerunners. The English manufacturer is an authority on Greenhouse design and use over the decades, having been making its beautiful and elegant handmade, made-to-order horticultural buildings for over 84 years from its original factory at the base of the dramatic Pennines’ Chew Valley in Greenfield, Lancashire. It has become synonymous for crafting the finest Greenhouses money can buy through the very highest standards of hard-won experience, craftsmanship and service. A hugely respected brand within the horticultural world, it is the manufacturer of choice for leading organisations, institutions and designers with Hartley Botanic structures commissioned by the RHS, the National Trust, Kew Gardens, Glasgow Botanic Gardens, Massachusetts Horticultural Society, Oxford Botanical Gardens, Le Manoir aux Quat'Saisons, Blenheim Palace, The Lingholm Estate and Hampton Court name a few. Its entire product range is endorsed by the Royal Horticultural Society.


All Hartley Botanic’s Glasshouses and Greenhouses are handmade, bespoke and made to order. Customers interested in purchasing a Hartley Botanic Greenhouse should visit: or call 781-933-1993 for more information.


Watering seedlings in the Hartley Highgrow Greenhouse


A Hartley Botanic Victorian Planthouse Glasshouse with roller shades


A Hartley Botanic Victorian Villa Glasshouse with roller shades


Harvest crops regularly in the summer months


Citrus crops growing in a Hartley Botanic bespoke lean to in Wiltshire

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