Tomato Fertilizer

Hi Jason -- I've been looking for your recommended 10-55-70 fertilizer -- do you have a source for it? My indoor tomatoes are not blooming!!! Thanks, Debbie

Answer Debbie- on my tomato growing page I mention 10-55-70 fertilizer only as an example. The important thing to keep in mind when picking out a fertilizer is the ratio of Nitrogen to Phosphorus to Potassium, which make up the N-P-K numbers on a fertilizer. When tomatoes are ready to bloom, they require less Nitrogen and more Phosphorus and Potassium (especially more Phosphorus). Any of the following fertilizers would do fine (as would many others with similar ratios)...

10-20-20
5-15-15
15-30-20
1-3-2
12-24-15

Again, these are just random examples. When using fertilizers with higher numbers, it will require less fertilizer to reach a particular fertilizer strength. When using fertilizers with low numbers, it will require a little more to reach a particular fertilizer strength. The important thing is the ratio of nutrients.....when you go to the store to purchase fertilizer, you will find that most "bloom" or "flower" formulas fall nicely within these rough guidelines.

In your question you mention your tomatoes are not blooming. It is very possible your problem has nothing to do with fertilizer. Outdoors, the main factor responsible for flowering/fruiting is darkness (lack of light). As the days get shorter and nights get longer, light-sensitive hormones (in most plants) detect these changes and trigger the plants to stop growing vegetatively and to begin flowering/fruiting.

So, the key to producing veggies on many plants is to first grow them to a reasonable (or mature) size vegetatively, than begin giving them 12 hours of uninterrupted darkness every night, at the same time night after night (a digital timer is very useful for this). This is known as flower forcing, and you can learn more about the process on my page how to force flowering.

My gut instinct tells me this is most likely your problem....even when given a vegetative stage fertilizer, tomato plants will still bloom if they are receiving a 12 hour dark period every day. So, make sure your tomato plants are receiving a period of complete darkness every night, and within about two weeks you should see tomato flowers begin to develop. I hope this helps!