Question
Can I use the regular lawn fertilizer for Vegetables, Flowers, Trees? What do you recoomend?  

Answer
Nonononononono Muhanad!

'Lawn Fertilizer' is usually WAY too high in Nitrogen for Vegetables, Flowers and even Trees!

Fertilizer by law carries a guaranteed 'N-P-K Analysis' -- a promise that inside the bag you'll get a certain percentage of Nitrogen (N), Phosphorous (P), and Potash (K).  All green plants need 13 minerals to grow.  But three -- Nitrogen (for green leaves), Phosphorus (for strong roots) and Potash (also called Potassium, used for life processes and cell growth) -- are used a LOT.  Since plants need so much of them, the theory goes, the plants will use all of them up.  Your bag of fertilizer is supposed to replace used up N P K.

But a plant with a lot of leaves is going to need a lot more Nitrogen than a plant with a few leaves.  A plant that flowers will need more Phosphorous than a plant that is not producing flowers.  So you can see that a bright green blade of grass is not going to need Phosphorous to make flowers or fruit.

That said, let's figure out what you DO need.

If you are growing Vegetables -- Carrots, Tomatoes, Broccoli, maybe Basil or herbs -- you must separate these into the kind of plant you have.  Chives and Basil are LEAVES, so a little Nitrogen is going to be great for them!  BUT if you are thinking of using a bag of Scotts Lawn Fertilizer, make ABSOLUTELY SURE it does not have any weed killer mixed in.  Because the weed killer will nix any chances of growing vegetables once you put it down.  In case you haven't noticed, I am not a big fan of the Scotts Companies, and if they have the guts to read this, I would ike to ask them how they sleep at night doing the things they do to the planet and the people who work for them.  But I digress.  Let's get back to your beautiful summer garden plans.

If you have Trees, say if you have Orange Trees, you want to make sure the Trees have not just enough N for leaves, but especially Phosphorous for the Oranges!  Right?

See how this works?

If you are growing Petunias, and Geraniums, and Roses, you want to make sure you are not giving them a lot of leaf-growing fertilizers.  Because if you do, the flowers will not be so great, but their leaves will be thick and lush.

What do I recommend?

I recommend a soil test, Muhanad!  Tell me your zipcode and i'll tell you who to reach for a soil test.

Then tell me what you want to grow.  I'll tell you how to do that.

Hint: My favorite fertilizer is Compost Tea.

But that's for another day.  rsvp and thanks for writing!