Growing tomatoes can be such a rewarding experience, especially when you harvest a healthy crop that goes straight from the garden to your kitchen table. We’re sharing advice on how to care for your tomato plants year-round, including essential seasonal steps and common pests and diseases to watch out for.
Potential problems for tomato plants
Tomatoes are susceptible to various pests and diseases. Spotting issues early and practicing good garden hygiene is the way to keep your tomatoes healthy and happy.
Aphids, fruit flies and mites
Some of the most common tomato pests include aphids, whiteflies, and spider mites, which feed on plant sap. When left untreated, your tomato plants can have stunted growth and won’t be able to produce as much yield. It’s always best to get on top of pest problems as soon as possible, so be sure to keep an eye out for them once you’ve planted your tomatoes.
To combat aphids and whiteflies, spray your plants with insecticidal soap or neem oil. For spider mites, spray the undersides of leaves with water and then apply some neem oil or insecticidal soap to get rid of them and deter them from returning.
Fungal diseases
The most common diseases for tomato plants are powdery mildew, Septoria leaf spot and early blight. Powdery mildew shows up as little white patches on your plant leaves and is typically caused by low soil moisture and high humidity levels at the plant’s surface. To treat it, trim your plants to remove the infected leaves and increase airflow, and dial down the humidity by watering your plants early in the morning before the sun hits. You can also try spraying fungicides or use a natural mixture of potassium bicarbonate and water to spray on your plants.
Septoria leaf spot looks like dark-bordered spots on lower plant leaves. When left untreated, it can make your plant lose its leaves over time. Prevention is key, so keep up good garden hygiene by rotating your crops, planting disease-resistant tomatoes and properly discarding any dead plant debris at the end of each season. Remove the affected leaves with a pair of pruning shears and use the same fungicides or potassium bicarbonate water solution mentioned above to treat Septoria leaf spot.
Poor garden hygiene can also lead to the spread of early blight, which shows up as small dark spots on leaves and stems and continues to grow larger if left untreated. Severely affected leaves, fruit or stems can turn brown and die, so this needs to be treated as soon as you identify it. Make sure you periodically remove plant debris from your garden beds, space out your plants, rotate crops and apply treatment with fungicides to break the disease cycle and maintain healthier soil.
Damaged fruit
If you’re starting to spot cracked or split fruit during harvest time, this is typically a telltale sign of inconsistent watering. A general guide is to give your tomatoes a good drink each morning, around the same time. Feel free to give them a top-off in the evenings on particularly hot days.
Sunscald on tomatoes is a condition where prolonged exposure to intense sunlight causes pale, whitish patches on the sun-exposed areas. To combat this, provide some shade with sheets and stakes when the sun gets too hot.
Blossom end rot shows up as dark, greenish-brown to black circular patches at the end of the fruit. It’s caused by calcium deficiency and is often made worse by overwatering or soil issues. You won’t be able to save the affected fruit, unfortunately, so go ahead and discard them. To prevent blossom end rot from affecting future fruits, make sure you keep your soil consistently moist with watering and mulching. You can also apply a good quality tomato fertiliser that contains calcium to balance out the nutrient deficiency. Keep monitoring for healthy progress and your plants should recover.
Seasonal care for tomato plants
Spring
If you've nurtured seedlings indoors over the winter, now is the time to move them into their designated spots in your outdoor garden. Start by incorporating a phosphorous-rich fertiliser into the soil before planting, two weeks before blooming begins and again when you notice fruits starting to grow. Be sure to avoid direct contact between your plant and the fertiliser to avoid potential burning. Continue regular care by ensuring adequate sunlight, watering consistently to keep the soil evenly moist, and providing support structures like stakes or cages as they grow.
Summer
Summer is the time to harvest! Continue to water your tomato plants consistently, focusing on watering at the roots. A general guide is to water once in the morning and additionally at night if the weather has been extra hot. Make sure to include a liquid fertiliser every four to six weeks to keep your tomatoes healthy and happy. Keep an eye out for any potential pests or diseases, removing any dying stems or leaves early to prevent any spreading. Now for the best part: pick as many juicy, sun-ripened tomatoes as you can. This helps to promote healthy growth, contributing to a bountiful and sustained harvest throughout the rest of the growing season.
Autumn and winter
As the weather begins to cool down, damage may start to settle into your tomato plants. Tomatoes are generally annual plants and need to be replanted each season. This usually means autumn and winter are the times to dig them up and prepare the soil for a fresh crop in spring. However, if you’ve planted your tomatoes in a pot, you may be able to keep them going by moving them inside to a spot that has sufficient light and a consistently warm temperature.
For more tomato growing advice…
Check out how to grow tomatoes.