What kind of fertilizer can I use for greenhouse tomatoes? (2024)

FAQs

What kind of fertilizer can I use for greenhouse tomatoes? ›

For greenhouse tomatoes, buy a premixed soluble fertilizer formulated specifically for greenhouse tomatoes. An all purpose greenhouse fertilizer, i.e. 20-20-20, is a poor choice for tomatoes. Tomatoes need a grade with much lower nitrogen and much higher potassium, as well as several other essential elements.

A common fertilizer program is to use a 7-1 1-27 plus calcium nitrate. The 7-1 1-27 is mixed at a rate of 15 ounces per gallon to make a concentrate stock solution. The calcium nitrate is mixed at 10 ounces per gallon of stock solution. These two stock solutions should be in separate containers.

Most greenhouse crops do best with a combination of ammonium and nitrate nitrogen. Unfortunately organic fertilizers generally don't contain nitrate-nitrogen.

If only one type of formulated fertilizer is used, it's best to choose a balanced product such as NPK 10-10-10. When should I fertilize my tomato plants? You should fertilize your tomato plants just before or during planting, around two weeks before bloom begins, and again when the first tomatoes are small.

An all purpose greenhouse fertilizer, i.e. 20-20-20, is a poor choice for tomatoes. Tomatoes need a grade with much lower nitrogen and much higher potassium, as well as several other essential elements.

Tomatoes do well in large containers and growing bags in a greenhouse or outdoors in full sun, and are very productive in a small space. Use peat-free loam-based or multi-purpose compost. Plant one tomato plant in a 30–45cm (12–18in) pot and two in a standard growing bag.

However, it is generally accepted that a constant feed (soluble fertilizer at each irrigation) is the best system to optimize plant growth. A constant feed program may also be modified so that nutrients are applied at every other irrigation. This approach may be necessary under conditions of high soluble salts.

A significant source of greenhouse gas (GHG) emissions comes from the manufacture of synthetic nitrogen (N) fertilizers consumed in crop production processes. And the application of synthetic N fertilizers is recognized as the most important factor contributing to direct N₂O emissions from agricultural soils.

From this point on I stick with the Blossom Booster 10-30-20. The high potassium will let the fruit finish nicely. Apply the fertilizers every 10 days or so right through the end of the crop.

15-30-15 can be used to remedy phosphorus deficient soils. Plant-Prod 15-30-15 High P fertilizer is recommended at the beginning of growth, as required by many greenhouse crops, in particular by tomatoes and cucumber grown in open ground.

Can you use 12-12-12 fertilizer on tomatoes? ›

There are precious few plants in containers for which it could be said that 1:1:1 ratio fertilizers like 20-20-20 , 12-12-12, etc, would be appropriate, but for tomato seedlings it would be.

Here's a simple recipe for side-dressing tomatoes: When fruit begins to develop, spread ½ cup of a 5-10-5 fertilizer around the base of a tomato plant. Gently work the fertilizer into the top inch of soil. Fertilize tomatoes again with a ½ cup of 5-10-5 when the first fruit is harvested.

Use a Sea Salt Fertilizer

It's true that a lot of salt can be bad for plants, but several studies and taste tests have shown that tomatoes grown with salty, brackish water end up tasting better.

The best way is to attach a wire across the greenhouse, making sure it is taut, then attach a cane to the wire. Another way is to tie a piece of soft string to the wire then tie the other end loosely to the base of the tomato plant.

Mechanical pollination

Shaking or vibrating of each flower cluster needs to be done every other day. It's best done in the middle of a sunny day with low relative humidity (about 70%). You vibrate the flowers by touching the stem of the tomato flower for a few seconds.