Why Your Vegetables Stop Thriving in June – and The Small Changes That Will Restart Growth in No Time
June can be a surprisingly stressful month for your veg plot, here's how to make it thrive
If you're a keen veg grower or new to the joys of home-grown produce, June can be a surprising month in the kitchen garden. The temperate months of spring – and with them all that lush, green growth full of hope – can suddenly disappear and you can be left with a plot that looks lacklustre and distinctly lacking in vigor.
This abrupt change in pace is so common it has a name: the 'early summer stall'. There are a number of reasons this happens, and the good news is there are solutions to them all. The five principal reasons vegetables stop thriving in June are changing temperatures, lack of water, nutrient imbalances, heat stress and the natural decline in cool-season crops. Any one of these (although it's often a combination) can cause growth to stall and veg plants to struggle.
To breathe new life back into your vegetable patch, I've dug deep into the five issues affecting your crops in midsummer to find the simplest, most reliable remedies. Your kitchen garden will soon be back to its burgeoning best, healthy and productive until fall or even beyond. And then you can turn your thoughts to what to plant in June.
Changing Temperatures
With June temperatures ranging from lows of around 60°F (16°C) in the Northeast of the US to 100°F (38°C) in the Southwest, and 54°F (12°C) to 86°F (30°C) in the UK, with even the occasional frost not unheard of, the extremes are a whole lot greater than 'gentle June' may suggest. It's no surprise then that your carefully tended vegetable plants could struggle to adjust.
When plants experience dramatic changes in temperature, it causes severe stress. Sudden periods of cold can damage plant tissues, cause yellowing of the leaves and result in stunted growth. Meanwhile, heat spikes lead to rapid water loss, which risks your plants going to seed, or 'bolting'. These sudden changes in temperature are more common in US zones where two different climates meet, and in hilly areas or deep valleys.
To avoid damage from cold temperatures, always keep some horticultural fleece handy (try these fleece jackets from Lowes). Check nighttime temperatures daily and throw fleece over vulnerable crops before nightfall. Cloches (whether DIY cloche ideas or store bought), veg row covers and coldframes are also super handy moveable options to minimise stress caused by extreme, sudden cold snaps.
Shop plant protection domes at Amazon.
Buy a portable mini greenhouse coldframe at Home Depot.
Lack of Water
June rainfall across the USA can vary drastically, but generally averages 3-6in (80-144mm) overall, with parts of the Midwest and Central Plains often dealing with dry spells and flash droughts. In the UK, summers are increasingly unpredictable, with a volatile mixture of showers, often very hot sunshine and an average monthly rainfall of just 2-3in (50-80mm). It's one of the driest months of the summer.
How best to water plants in June? An irrigation system, like this soaker hose from Amazon, set on a timer is a huge help if rainfall is unpredictable, failing that make watering part of your early morning routine. The best time to water the garden in summer is before 9am, when the sun is often hot enough to significantly affect water lost through evaporation.
Remember always to direct water to the base of your plants, using the spout rather than the sprinkler attachment of your watering can. Any crops growing in pots will need careful attention if they're not to dry out.
A generous 2-3 in mulch of organic matter (ideally applied after a good soak) will help to lock in moisture and prevent water loss through evaporation. It will also help to lock in nutrients, in fact adding goodness to the soil as it breaks down and decomposes.
Straw, compost, manure and grass clippings are some of the most effective and nutritious organic mulches to use in a veg garden. Avoid bark chippings as they can remove nitrogen from the soil as they decay: annuals such as veg plants need plenty of nitrogen to grow strongly.
Shop garden straw at Lowes.
Nutrient Imbalance
When you first plant veg in spring, with decent rainfall and seasonal sunshine, chances are they'll start to grow quickly. After a couple of months, if your soil is poor or presenting challenges, that will start to show in the health of your plants.
They're bigger, putting on more vegetative and root growth, and likely starting to develop fruit, so their needs are more complex. Overfeeding your plants is also a possible pitfall. Here's how to choose the best fertilizers for your veg garden.
Lack of nitrogen
If older plant leaves are yellowing or turning pale, chances are they're in need of a nitrogen boost. Use a nitrogen-rich feed such as nettle tea or other high-nitrogen fertilizer, or work in some well-rotted manure to boost levels and restore nitrogen to your soil.
Lack of phosphorus
Spotted a purple or reddish tint to young growth? Is it perhaps in addition to poor flowering and slow root growth? Then you may need to add phosphous to your soil. This is simply done with a sprinkling of bone meal or rock phosphate.
Lack of potassium
If the edges of leaves are browning or yellowing, or your harvest is poor quality, potassium could be the issue. You can fix this with a dose of wood ash, seaweed feed, or comfrey tea.
Lack of calcium
Blossom-end rot on your tomatoes and zucchini or tip burn on your lettuce? Then your soil's probably in need of a calcium boost. Fork in some crushed eggshells, garden lime or gypsum to rectify this deficiency.
Too many nutrients!
If you've gone a little OTT with synthetic fertilizers, it can have a detrimental effect on your young veg plants, burning their roots and creating an overly salty soil environment that actually draws moisture out of your plants. It's one of the most common fertilizing mistakes and signs include crisp, brown leaf margins, lush growth without any sign of fruit and yellowing leaves that can wither and drop.
Fix this by removing the top inch of soil and replacing with fresh compost (if it's slow-release granules or top-dressing that's the cause), or soaking your veg beds thoroughly and deeply to wash away excess fertilizer from the roots.
Shop plant food and fertilizer at Target.
Heat Stress
Across the US and in the UK too June isn't too early for vegetables to start showing heat stress, which tends to happen when the mercury hits around 85°F (30°C). When vegetable plants are stressed from too much heat, it can affect not only their growth but also pollination.
Signs your plants are suffering from heat stress include curling tomato and pepper leaves (usually upwards) in a bid to reduce water loss, tall 'bolting' stems emerging from lettuces, blossom drop and poor fruit set.
Deep, targeted watering will help (in the early morning), as will setting up shade sources. These can include shade cloths, which will lower temperatures around plants, reduce leaf scorch and stop plants like peppers and tomatoes stalling). 30-50% shade cloth is best for sun-lovers like tomatoes, cucumbers and peppers, as well as young seedlings; 70%, like this one from Ace Hardware is best for other veg. But an old sheet is better than nothing at all!
Less costly is moving tougher, more heat-resistant containers in place to provide portable shade. Think large pots of geraniums, rosemary, lavender and salvias. Or try pots of sunflowers to shield seedlings from sunlight. Shift these to the south/southwest side of your veg beds (raise them up on bricks if you can) and you'll add an element of shade when the sun's at its hottest – to help with this try wheel plant caddies like these from Lowes.
For taller crops, it can be useful to place a large upturned pot on a stake to act as a parasol over individual plant. Remember too that moving container-grown veg into more shaded spots in the backyard. will help to reduce the effects of heat stress.
You can improve airflow around plants with some strategic June pruning. Removing the lower leaves from tomato plants will let in air and thinning out overcrowded foliage and crossing branches provides natural ventilation to help plants breeze through a heatwave.
Meanwhile, to help pollination, add in a few pollinator-friendly flowers to your veg plot. French marigolds (Tagetes), cosmos, zinnias and lavender are some of the best plants for pollinators.
One last tip: avoid fertilizing when the weather is very hot, as it will trigger a sudden onset of tender growth, which is difficult for the plant to sustain when temperatures are especially high.
Shop pollinator favorites at Burpee.
Decline in Cool-Season Crops
There are certain crops that just won't thrive in warm weather, whatever you do to combat it. And that's because they're simply not built to grow and fruit in high temperatures. So if your radishes have turned woody and won't germinate, fret not: their time has passed, but there's always next spring.
This is also partly true of other root veg including carrots, turnips and beetroot, which are often best sown early and harvested in early summer. They're what's known as cool-season crops, which need to be sown/planted early in the year for early harvests, before the weather turns scorching.
These crops, as well as salad leaves and alliums will naturally begin to decline from now until late summer, but to keep roots from turning woody continue with your deep watering, keep those salads shaded and mulch away to lock in moisture.
June is often a time when gardeners easily relax and think the garden will take care of itself. But it pays to be vigilant and aware of the challenges of vegetable growing in June, and bear watering and heat spikes in mind.
As you can see, there are plenty of low-effort ways to protect your veg crops and keep them thriving through early summer. Better still, your efforts now will pay dividends for the rest of the summer and into autumn as crops mature and harvests begin in earnest.
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