How to Grow Eggplant in Cooler Climates

, written by Benedict Vanheems gb flag

Eggplant

Delicious as eggplants are, any of us growing in temperate climates will undoubtedly find them just a bit of a struggle. Eggplants hail from India, where temperatures can occasionally top 50°C or 122°F (yes, really!). So with cool, northern summers it should come as no surprise that these plants need as long a growing season as we can possibly muster; it’s very much a case of early to rise and late to bed for these tropical beauties!

Gardeners in temperate climates who try growing aubergines are all-too-often faced with disappointment. Plants put on lackluster growth, possibly flower and may – just – produce one or two puny, chicken egg-sized fruits. (Perhaps that’s why they’re called eggplants?) I lay part of the blame at the feet of the seed companies, who make outrageous claims that many of the varieties they sell will give a good crop outdoors if grown ‘in a sunny and sheltered position’. That may be the case in a heat wave year, but for a typical summer in the UK I’m afraid this advice simply doesn’t cut it. The only solution for those contending with leaden skies and drizzle comes in the form of a greenhouse where temperatures will sit a few degrees above those outside – enough to make all the difference.

Of course, I cannot speak for those blessed with a warmer climate. There the consistently higher temperatures will more than make up for the longer hours of summer daylight experienced by those of us at higher latitudes. Most American gardeners should be fine growing their eggplants outside following an early start under cover, while those in the Southern states will be able to sow directly outdoors. What follows is advice for those gardening in weaker sunshine levels and unpredictable summers.

Eggplant seedlings

Sow Eggplant Early

Don’t wait until spring to make your sowings, start your eggplant off in late winter. You will need to coddle the seedlings but I promise it will be worth it. To minimize root disturbance and make life easier I sow the seeds into modules of seed compost, though you could of course sow into pots of compost and prick out the seedlings into their own pots once they are big enough. Being in the tomato family the seeds look much the same, so they are easy to handle and sow individually. Cover them with a layer of vermiculite or compost and pop them into a heated propagator. Ideally you will want a temperature of 24°C (75°F) for speedy germination, although 21°C (70°F) would be adequate. Keep the compost moist but certainly not wet.

Seedlings should make an appearance within 10 days to two weeks, at which point they can be left to grow on before potting on into 7cm (3in) pots of multipurpose compost/potting soil. Keep them on the warm side with plenty of natural light and pot on again into 12cm (5in) containers as soon as the roots can be seen at the drainage holes. The plants can go into their final positions once they fill these pots, though you will need to make sure you can sustain a cozy environment.

Eggplant

Hot Topic

The question now is how to boost the ambient temperature to coax your plants into flower and, ultimately, fruit. You have two options here: the warmth of a greenhouse or, for the more adventurous or those that don’t have a greenhouse, an enclosed hotbed. Most gardeners may not have heard of a hotbed, let alone used one. A hotbed has nothing to do with heated blankets or sun/tanning beds, but rather the joy of muck or, to be more precise, decomposing muck! As manure breaks down it gives off impressive heat, raising the surrounding temperature on a cold day by as much as 10°C (about 18°F). Hotbeds take advantage of this natural decomposition process by using the heat given off to cajole tender plants into productivity.

Constructing a hotbed is straightforward enough, even if it does require an initial input of muscle. First, dig out a bed to a spade’s depth, fill it with manure (horse is best), then turn it after four days to ensure an even mix of the bacteria and fungi responsible for decomposing. Once it’s kicking off heat decomposition has begun and the muck should be topped off with a 10-15cm (4-6in) layer of soil. Leave for a further few days for the mounded bed to settle then plant your eggplants into the soil layer.

To prevent all that hard-won heat from escaping, enclose your hotbed within a cold frame or similar structure, such as a tomato house. You can either dig out the hotbed in an existing frame or lift the structure into place afterwards. Needless to say it makes sense to dig the hotbed to the same dimensions as your covering structure. Eggplants will grow upwards of 90cm (3ft) in good conditions, so make sure the frame or tomato house you use is tall enough for the job. Frames that aren’t tall enough will still give plants a really strong start, even if you have to lift the lids off once the foliage is touching. Fleece can be draped over these plants at night to keep off the chill then removed during the day to allow pollinating insects access.

Greenhouse eggplants should be grown one plant to a pot of at least 30cm (1ft) diameter. Open vents so that bees and other pollinators can find their way in.

Eggplant flower

Final Steps to Success

To keep eggplants stocky and sturdy remove the main growing point of your plants once they’ve reached 30cm (1ft) tall. This will encourage further branches to develop lower down, thereby ensuring a bushier and shorter plant. Branches may need supporting with canes, particularly when they begin to set their (hopefully) weighty fruits.

Even when growing with lots of compost or manure, both hotbed and greenhouse eggplants will benefit from a weekly liquid feed high in potash to encourage flowers and fruits; tomato feed is fine for this. In cloudy or cool weather gently tap the flowers to encourage pollen to dislodge and fertilise the flowers. Mature fruits can be cut away with a sharp knife; cut them while they are still shiny as dull fruits will be past their best.

Finally, if you are looking for a strong performing variety to give you a head start then I recommend the fulsome ‘Black Enorma’, whose heavy fruits should reward you with plenty of classic black fruits.

By Benedict Vanheems.

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Comments

 
"Thanks for some really helpful information. My eggplants have been an irritation every year. I live in souther Oregon where summers are hot and dry, but not long and it always is a challenge to produce any fruit, let alone full sized ones. With plenty of goat manure composting over the winter, I'm going to try a hotbed-thanks for the info!"
Gerrie on Friday 27 January 2012
"I have found that varieties with smaller fruits set more a ripen in time here in Portland, OR. I think it was fairy tale that was so successful but I did it in a pot in the sun too."
Jill on Wednesday 1 February 2012
"I will certainly give this a go - My aubergine plants grow well but have never set fruit. I usually don't sow the seed until April and always keep them in the greenhouse. I will be sowing them in the next few days and see what happens."
Margy on Friday 3 February 2012
"I successfully grew a bumper crop of fingerling eggplants last summer. I had more than I could eat! I'm just north of Toronto, Canada in zone 5b. It can be done, but as Jill mentioned above, the smaller fruits definitely grow better in this climate."
Kimberly on Friday 3 February 2012
"I live in the west of England and last summer, no sun, was dismal even with a green house. I had planted in beds rather than the usual 10L pot and had strong plants but little fruit. I use Moneymaker and Long purple but even they need sun!"
ed on Sunday 12 February 2012
"Thank you for the info on hotbeds. Will try to incorporate a row in my raised beds....thinking this might work for peppers, too? "
Sharon on Monday 13 February 2012
"Hi there I live in Auckland NZ and have grown aubergine plants success fully for years. I have been buying grafted plants lately and they have produced great fruit This year, right now here in NZ, these plants are fruit filled but now my plants are turning their toes up and dying. Like they are dry and wilting from heat and dehydration but they are not dry The leaves look normal though wilty - no outward sign of disease - this is a disaster. Any ideas? "
David on Wednesday 23 January 2013
"I live in Christchurch NZ and have never had much luck growing eggplants. I have them growing in a glasshouse this year but with 6 plants I only have one eggplant growing,they always seem to flower but that is about it,I have no idea what I am doing wrong.If anyone could give me some advise I would really appreciate it."
Amy on Thursday 21 March 2013
"Amy, the lack of aubergines on your plants could be due to their growing in the glasshouse where there are likely to be far fewer pollinating insects. Ensure windows and doors are open when weather allows to enable bees and other pollinators access. To be completely sure I'd artificially pollinate the flowers. Do this by gently swishing the flowers with an artists paintbrush to distribute the pollen. Move from open flower to open flower, to mimic the actions of bees. This should improve fruit set for next year."
Ben Vanheems on Monday 8 April 2013
"Hi Ben Thank you so much for your advice I will try that for next year. Regards Amy"
Amy on Monday 8 April 2013
"I live in Hamilton NZ and have grown aubergines successfully for a few years now. I soak the seeds before planting in August each year and keep the seedlings growing by a window (double glazed so not drafty) until it's warmer outside. Once the days are warmer I put them outside during the day and then return them indoors. I pot them on when about 6 cms and give them a worm "wee" feed. When the soil is warm enough (usually early November) I plant them out facing the sun and where they would received them most sun all day. I also usually grow beans/peas along side them as a windbreak. I stake them early to avoid disturbing the roots and mulch them heavily and feed them with comfrey tea. I usually plant about 20 plants and get a crop of about five large and several smaller fruits per plant. I feed them with worm "wee" and comfrey tea alternate weeks. I love growing them and love to eat them! They do get alot of care taken off them and I've had great crops each year. "
Lu Cope on Friday 12 April 2013
"Hi Lu. It sounds like you've got a fantastic recipe for success there. Liquid feeds from a worm composter are full of the good stuff!"
Ben Vanheems on Friday 12 April 2013
"Hi Lu. I have never heard of the 'worm wee' before but will try that for next year and hopefully have some success because like you I absolutely love eggplants and hate not being able to grow them.Thanks for the advice.:)"
Amy on Friday 12 April 2013
"I grew Aubergines when I lived in Spain but since returning to the UK have been really unsuccessful...not even a flower so this year I have bought plants and am nurturing them with everything crossed."
Kay on Saturday 8 June 2013
"I grow eggplants outside in Dunedin, NZ. Only grow the Japanese varieties .ie small ones. The best of these was Long Tom F1 hybrid but I cant get this now. Current best is Tokyo black. Would love to hear about other likely varieties. Because of lack of space I grow in pots and they are near the north facing wooden house wall. We are plagued by earwigs because of street lights and they do take a toll of the plants. Flowering and fruiting are no trouble. I just treat them like tomatoes."
Jennifer on Wednesday 25 September 2013
"I live in the East Midlands UK. Last year we had a late summer, I grew the seeds in doors in late March and then put them outside by end of may in larger pots. Come August I had some fruit growing but then the plants started to wither slightly. I put them in the Green house and they were fine till Novemeber. I managed to get at least 12 fruits from the 6 plants I had which was not bad since i sowed them late and it was the first time I planted them. I planted mixed variety seeds."
Mubeen on Tuesday 11 February 2014
"Hi Mubeen. That is a really good result. Growing a mix of varieties might have helped spread the risk and increase the chances of harvesting more fruits over a longer period of time."
Benedict Vanheems on Tuesday 11 February 2014
"Hi Benedict! Thank you for writing this article! Being a Dutch egg plant grower, I am finding it very helpfull. I started growing my first egg plants (from seed) last February. I'm hoping to plant them out in a month or so. I have been reading a few articles by other experts(?)on growing egg plants lately and I noticed that unlike you they advise people to leave the main growing point (and 2 or 3 extra stems)on the plants and pick of so called 'suckers' off the side of the main stem a soon as the first flowers appear. I am all in favour of a smaller, bushier plant, but will nipping out the top as you suggest not encourage these energy draining suckers? Or should they still be picked out? Hoping you can help!"
Dammes on Thursday 1 May 2014
"Hi Dammes. Nipping out the growing point at 30cm tall will help to create a sturdier, stockier plant. This is preferable to leaving the plant to grow on and get tall and leggy and possibly less able to support the fruits. Once the branches have developed any sideshoots that develop from these branches should indeed be pinched out (like tomatoes) so the plants concentrate on producing fruits. Allow about three fruits per plant."
Ben Vanheems on Friday 9 May 2014
"Hi Ben, Thank you for your reply. All is clear to me now. Your advise sounded good so I already nipped out the growing points. The plants look really healthy and I enjoy watching them grow, especially their leaves; they sort of look like my bicycle saddle, only bigger.. :)"
Dammes on Monday 12 May 2014
"I am in Warwickshire, UK and have 1 plant in a polytunnel - with 9 fruit growing well so far and about a dozen more flowers that are setting; the plant is about 18" tall and very healthy but I am not sure whether to remove any of the flowers or smaller fruit - any advice welcome; Thanks"
Andrew on Sunday 6 July 2014
"Hi Andrew. Sounds like your aubergine's doing really well, especially given it's so early on in the summer still. I'd let the flowers continue for now as there's still at least three months of good weather left in a polytunnel environment. I'd maybe consider removing flowers from mid August to allow the fruits that remain to fully mature."
Ben Vanheems on Sunday 6 July 2014
"Hi Benedict. I really enjoyed reading you. I live in North BC, Canada. I have one plant, in a greenhouse, on my balcony. Me growing that eggplant was a last minute decision. It was one of the last few plants left at the store. Since I like eating it, I decided to go for it. My plant is now 12" tall. It has 10 unopened flowers. It has 3 sideshoots. I was wondering if I should take them off since it is late in the season."
Sylvie on Friday 1 August 2014
"I'd leave the sideshoots, left all mine have a wonderfully bushy healthy plant :-) "
Andrew on Friday 1 August 2014
"I am in the northeast of England and have been growing eggplants for years very successfully. I have two large greenhouses and start off my plants in one which has a hotbed along both sides which adaquatly heats the greenhouse through all of the winter ( with constant topping up throughout) allowing me to grow eggplants as a perenial. As the weather improves I gradually move them to the other greenhouse which has a smaller hotbed to frost guard them. it is the middle of may and my plants are maybe a week off flowering which I pollinate by hand"
david on Saturday 16 May 2015
"Hi David - it sounds like you've got a really thorough system set up there. Having plants in flower by the end of May is very impressive!"
Ben Vanheems on Monday 18 May 2015
"Hi Ben Thank you but you have to remember these are established plants succesfully over wintered and not grown from seed each year. plus both greenhouses are south facing, insulated and fairly well sheltered from cooling winds. I do grow a few from seed each year just to replace ones I have lost during the winter those are a long way off flowering"
david on Monday 18 May 2015
"Just a little tip for those in areas that could have cold snaps early in the growing season. (It has always worked for me) Keep your seedlings and such almost dry (just on the moist side) dry or almost dry compost will warm up a lot faster than wet compost. spray the compost as apposed to direct watering from a watering can"
david on Wednesday 20 May 2015
"Hi. I live in Northern Ireland and have been successfully growing a few aubergine plants in a polytunnel. Do I need to start again afresh next year or do I hold on to these plants, maybe reduce their stems, and then continue with the same plants next year? "
marie on Wednesday 18 November 2015
"Hi Marie. In theory you could keep aubergines going over winter, as they are perennial. However, they are very tender plants and need quite a warm temperature, so I imagine you would struggle in Northern Ireland. Poor winter light levels might also stall your efforts. I'd suggest it's better to start again in the spring with fresh seeds. However, don't let me be the negative one on this - it's certainly worth a go if you have the resources to keep temperatures warmer - perhaps by moving the plants into a conservatory? If you do this and success, please post again in the spring to let us know how you got on."
Ben Vanheems on Wednesday 18 November 2015
"Seems like aubergines would be perfect candidates for straw bale gardening. You wouldn't have to worry about burning your plants with N either."
Lindsay on Sunday 1 May 2016
"Hello Ben, Thank you for a very helpful article. If you are growing Aubergines this year, I wonder if you would write a little about how your plants are doing. I'm new to Aubergines, but I am committed to growing them this year. I'm seeing grey mould on the stalks of the flowers which drop off. One developing fruit started to go brown at the stalk end and it dropped off too. I've cut back on misting the GH to try to reduce the temperature in the GH, it seems to have helped a little. I'd value any comments or advice, thanks.. Jo"
Jo on Monday 26 June 2017
"Hi Jo. Apologies for the late reply to your query. I'm not growing any aubergines this year - concentrating on tomatoes. It sounds like your plants may have blossom end rot or similar. Make sure you keep the foliage completely dry by watering at the base of the plants. Very high temperatures (above 32C/90F) and uneven soil moisture are the big enemies of aubergines, so water regularly and apply a mulch if this is appropriate. You could also try damping down the paths and any other hard surfaces. Wetting them so that the moisture then evaporates, which will help to reduce the temperature in the greenhouse. "
Ben Vanheems on Monday 3 July 2017
"Hello Ben, thank you for your reply. The high temperatures we were having was the cause of my problems. I was damping down and misting the plants which left the leaves wet. I've since stopped misting and the plants have recovered. I cut the first Aubergine Viserba yesterday. Thanks again, Jo"
Jo on Monday 3 July 2017
"That's brilliant news, so pleased they're now cropping well for you Jo."
Ben Vanheems on Monday 3 July 2017
"Hi Ben, super article. Planted some 5 variety of tomatoes this year but all subjected to blight due to alternating hot then very damp weather. But the finger sized aubergines (Orlando variety) turned out beautiful, with four or so fruit much larger than finger sized. Hoping for a nice Mediterranean roasted veg next weekend with barbecue if weather holds out in south uk. Going to try the larger variety black beauty next year so getting propagator ready to give maximum length of season."
Sean on Sunday 27 August 2017
"Hi Sean. Sounds like you've had really good success with your aubergines - well done, as they can be touch and go in the cooler UK climate. My tomatoes have escaped (in Oxfordshire) the blight this year, so I've been very lucky clearly. Good luck for next year. As you say, the longer the season you can give aubergines the better. Enjoy your Mediterranean roasted veg!"
Ben Vanheems on Tuesday 29 August 2017

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