Fertilizer use


How do I side dress tomato , cucumber and eggplants?
When we use fertilizer to tomatoes growing in containers, should we reduce the amount of fertilizers used by half ( compared to tomatoes growing in the ground)
Is 20,20 , 20 fertilizer stronger than 10, 10, 10


Thank you for contacting the Toronto Master Gardeners. Side-dressing is the efficient application of fertilizer along the sides of a row of plants in the garden. Side-dressing is usually a boost of fertilizer that supplements the starter fertilizer that was applied at planting time. It is done to ensure that there is a steady and adequate supply of nutrients available so that the plants can produce a good crop. It is done by raking back the mulch if it is being used and then placing granular fertilizer in bands along both sides of the row, about six inches from the plant stems on each side. The fertilizer is then worked into the top inch or two of the soil, the mulch is replaced and then the plants are watered. Side-dressing is usually a high-nitrogen fertilizer because nitrogen is quickly leached from the soil but is also critical for good plant growth.

The timing for side-dressing is really important. If vegetables are given too much nitrogen at the wrong time they will produce lots of leaves and stems which can slow down or reduce the creation of fruits resulting in a smaller crop. This is the recommended timing for side-dressing your plants :

Tomatoes : 1-2 weeks before the first tomato ripens (this will be when the fruits are visible but really small), again 2 weeks after the first tomato ripens, then again one month later.

Cucumbers : 1 week after blossoming begins, again 3 weeks later.

Eggplants : after the first fruit sets (when really small fruits are visible).

Vegetables grown in containers are usually fertilized with a liquid or water soluble fertilizer. The directions on the label or box of any fertilizer apply to vegetables grown either in the garden or in containers, so the same dose for each. The approach to fertilizing vegetables in containers is different from vegetables grown in the ground. Vegetables in containers lose nutrients quickly because they are watered more frequently than vegetables in the ground and the water drains away. Vegetables in containers are often fertilized every other week throughout the growing season.

10-10-10 and 20-20-20 fertilizers are both complete fertilizers (they contain all three of the most important plant nutrients : nitrogen, phosphorus and potassium), and they are balanced fertilizers with a ratio of 1-1-1 (they have equivalent amounts of N, P and K). 20-20-20 is stronger than 10-10-10 : it has 20% of each of N, P and K vs 10% of each in 10-10-10.

Here are a couple of links with information about growing vegetables in the garden and in containers that might be helpful :

Vegetable gardening

Outdoor container gardening

Happy vegetable gardening !

June 4, 2021