There are tomatoes for indoor and outdoor cultivation.

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Tomato flower, photo: Rasbak CC BY-SA 3.0

Tomatoes – belong to the nightshade family (Solanaceae). Sow tomatoes in March for the greenhouse or on the warm windowsill. Once the plantlets are large enough to repot, put each in its own pot for the greenhouse or conservatory. There are also tomatoes for outdoor cultivation.
Pre-sow in greenhouse or warm window sill in March and in mid-May, in late spring or early summer, tomato plants can go outside. Place tomatoes in a sunny and sheltered spot in the garden. A shelter helps against the rain, because tomatoes, like potatoes, are very sensitive to Phytophthora
Once the tomatoes begin to color, they should be tied up and side shoots in the leaf axils should be removed (Pinching).
Tomatoes can be forced to flower faster by being sparse with watering for some time after transplanting. This causes them to flower earlier, and the earlier the flowering, the earlier the harvest. However, this method of forcing somewhat increases the chances of Blossom end rot, because precisely regularity (same time and same amount) of watering helps prevent Blossom end rot and cracking of the almost ripe tomatoes.
Tomatoes, like the potato and aubergine, belong to the nightshade family. Tomato plants also contain tomatine (sister of solanine), except for ripe tomatoes.


Green peach aphid on leaves, control, plant pest
Green Peach Aphid, Photo Scott Bauer – CC Public Domain

Curled leaves; in some places there is an aphid of about 2 mm in size: Green peach aphid (Myzus persicae).

recognize Greenhouse whiteflies
Greenhouse whitefly, photo: Gaucho – CC BY-SA 3.0

Leaf turns yellow and bumpy; eggs on the underside of the leaf: Greenhouse whitefly (Trialeurodes vaporariorum).

recognize eggs and nymps hairy shieldbug
Beetles just hatched from eggs, photo: Marlou Hesseling – Jansen

Beetles just hatched: Hairy shieldbug (Dolycoris baccarum).

Fungi & diseases

Late blight, photo: Rasbak CC BY-SA 3.0

Brown spots on leaves and stems: Late blight (Phytophthora).

Recognizing alternaria on tomato
Brown spots on leaf of tomato, photo: Jerzy Opioła – CC BY-SA 4.0

Small brown spots on the leaf, growing into large spots, after which the leaf yellows, curls and dies: Alternaria (Altenaria alternata).

Gray mold, photo: Tim De Mesmaeker

Incipient gray mold (Botrytis ssp.) on tomatoes.

recognize gray mold on tomato plant
Gray mold on tomato, photo: Rasbak – CC BY-SA 3.0

Tomato plant covered by gray fungal fluff: gray mold (Botrytis ssp.).

Bacterial cancer on tomato, photo: Alan Collmer – CC0 Public Domain

Brown spots develop on the leaves, after which leaves fall off prematurely: bacterial canker (Pseudomonas syringae).

Leaves at the end of a stem wilt, with the leaf not curling or coiling. Then more top leaves follow. A cut affected stem shows bacterial slime: Ralstonia solanacearum.

Recognizing Tomato Brown Rugose Fruit Virus
Mosaic pattern: Tomato Brown Rugose Fruit Virus, photo: EPPO global database

Dots and yellow spots on tomatoes, mosaic pattern on new leaves in plant head and young shoots, followed by mosaic pattern on tomatoes: Tomato Brown Rugose Fruit Virus (ToBRFV).


Blossom end rot, photo: Astrid

Brown, dry spots on the underside of the tomato: Blossom end rot due to unbalanced nutrition.

tomato, lime deficiency
Blossom end rot due to calcium deficiency, photo: Amun Chouhan

Dilated, rotten spots on the top or bottom of tomatoes: Blossom end rot, caused by calcium deficiency combined with too little water.

recognize boron deficiency in tomato
Growth points die off photo Goldlocki CC BY SA 30

If the pH is too high or too low, the growth points die: a deficiency of the trace element boron.

Tomatoes show water spots – water the plants at the roots.

Too much water, photo: Justine Be.

Tomatoes tear in final stage of ripening: irregular excess water (rain).

Leaf stalks grow from leaf axils: offshoots inadequately removed – pinching.

Leaves turn from dark green to reddish-brown and the leaf edges yellow. The tomatoes no longer turn red and the margins of new leaves turn yellow: potassium deficiency.

recognizing root formation on the stem of a tomato plant
Root formation on the stem of a tomato, photo: Monica Teunissen

Root growth occurs on the stems: this is quite normal in some types of tomato plants. If you put such a stem with root formation under the soil or in a cup of water, the roots just grow and a new plant is created.

Eaten tomatoes
By mice half-eaten tomato, photo: MergenMetz

Mice sometimes eat tomatoes. They can easily climb up along the stem. Lagging mouse droppings betray their presence.

recognize cause yellow spots on tomato plant
Yellow spots on young leaves, photo: CC0 Public Domain

Yellow spots on young leaves: over-fertilization due to too rich (potting) soil. Water frequently to prevent burning; plant recovers during season. Fertilizing the mature plant is unnecessary.

recognize peloric flower
Unusually shaped flower, photo Barry Taylor

Curiously shaped flower at the top of the tomato plant: peloric top flower. Normal potato flowers have five intertwined petals. Peloric flowers have eight to 13 fused petals. Sometimes these unusual flowers arise; in foxglove it is a regular occurrence. Can’t hurt.

recognize sunburn to tomatoes
Sunburn to ripening tomatoes, photo: Luc Van Simaeys

Tomatoes not covered easily develop sunburn during a heat wave. Prevent this by shielding the tomatoes in time with vitrage or with an umbrella. Do not cut away the leaves, as they will give shade. Water liberally. Remove the burnt fruit.

recognize damage caused by rats
Considerable damage from rat infestation, photo: Ria van Gael

Rats can do substantial damage to ripening tomatoes.

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