Tomato

Quick growing conditions

How to Grow Hydroponic Tomatoes Indoors

Growing hydroponic tomatoes at home lets you harvest ripe fruit just before eating it. You control plant nutrition and care, without the transport and lengthy storage associated with shop-bought produce.

Grow your home tomatoes without chemical pesticide treatments. Choose disease-resistant varieties, keep the system clean and inspect plants regularly. Good airflow and early pest detection help protect your harvest.

Hydroponic Tomato Growing Conditions

These are starting guidelines, not strict limits. Temperature, lighting, humidity and variety work together. Tomatoes can grow outside these ranges, but continued growth does not guarantee good fruit set. Heat during flowering is particularly important.

Kilolux readings are an approximate guide for white LEDs. They are not directly applicable to red-and-blue grow lights. Check light across the canopy rather than at one bright spot.

Choosing Tomato Varieties and a Hydroponic System

For limited indoor space, choose compact dwarf or micro-dwarf tomatoes. Cherry tomatoes are convenient for frequent picking, but “cherry” describes fruit size, not plant height.

Choose varieties with stated resistance to relevant diseases, such as Fusarium wilt, Verticillium wilt or leaf mould. Check the variety’s expected height and growth habit.

Indeterminate tomatoes keep producing new stems and flower clusters and need ongoing training. Determinate tomatoes form a more limited crop on a bushier plant.

Drip-fed substrate systems, including Dutch buckets, suit hydroponic tomatoes. DWC also works with continuous aeration and sufficient root space. Support the plant independently of the small growing basket.

Hydroponic Tomato Nutrient Solution and Care

Recommended Nutrient Profile

All values are in mg/L of the finished nutrient solution.

Source: Nutrient Solutions for Greenhouse Crops, Geerten van der Lugt and co-authors, version 4, 2020, page 53. The profile is for tomato feed solution in inert substrates. Each adjustment is calculated from the base profile.

Total N includes both nitrogen forms. P and K are expressed as elements, not oxides. High water supply means irrigation above 5 L/m² per day. End-of-crop adjustments apply after removing the growing point while the final fruits ripen.

Use this profile as a starting point, then adjust it to your variety, source water, system and plant response. Account for nutrients already present in your water.

Use our NPK calculator to calculate fertiliser quantities for your selected profile and water volume.

Check solution level, pH and EC daily. Mix thoroughly and recheck after topping up. EC measures overall salt concentration, not the balance of individual nutrients. Periodic solution replacement helps prevent imbalances.

Train indeterminate tomatoes to one or two stems and remove unwanted side shoots while small. Do not routinely remove all side shoots from determinate or micro-dwarf plants, as this can remove future fruiting growth. Keep healthy leaves and gradually remove damaged or ageing lower leaves.

How to Pollinate Indoor Tomatoes

Most tomatoes are self-fertile: a single plant can produce fruit. However, pollen still needs to move within the flower. Indoors, gentle vibration helps release it.

1. Find a flower cluster with fully open flowers.
2. Switch on a dedicated electric toothbrush or handheld pollinator.
3. Touch its vibrating back gently against the flower stalk or cluster stem for a few seconds. Avoid touching the petals or flower centre.
4. Repeat every other day while new flowers open, preferably around midday when flowers are dry and before the room becomes too hot.

Gentle tapping of the cluster can also help. You do not normally need to transfer pollen between flowers with a paintbrush. Excessive heat or humidity can prevent fruit set even when vibration is provided.

Harvesting Hydroponic Tomatoes

Pick fruit when it develops the variety’s mature colour and feels slightly yielding. Ripe tomatoes may be red, yellow, orange or another colour, depending on the variety. Support the cluster while picking, or cut the stalk with clean scissors.

Indeterminate plants can provide repeated harvests; determinate plants generally produce a more concentrated crop.

Common Hydroponic Tomato Problems

• Flowers drop without forming fruit: Check temperature, humidity, light and pollination.
• A dark patch develops at the bottom of fruit: Blossom-end rot involves inadequate calcium reaching developing fruit. Check water delivery, roots and EC before simply adding more calcium.
• Fruit cracks: Check for abrupt changes in water supply and avoid letting the system run dry.
• Whiteflies or fine webbing appear: Inspect leaf undersides for whiteflies or spider mites. Isolate affected plants and act early with suitable physical or biological controls.

Have questions about growing hydroponic tomatoes? Join our Telegram channel. We are happy to answer your questions and help with plant care and nutrient solutions.

Sources

• Nutrient Solutions for Greenhouse Crops, Geerten van der Lugt and co-authors, version 4, 2020, page 53