Fertilizer is not a 'one size fits all' kind of thing. First of all, before you go spraying anything, you need to know what kind of fertilizer do you have. I don't mean "Miracle Gro" brand, I mean, what are the NPK ratios. N is nitrogen, P is phosphorus, and K is potassium. There's way more to it than this, but the stripped down simple version is that nitrogen encourages foliage or leaf production, phosphorus encourages bloom and fruit production and potassium encourages root development.

These NPK ratios are on every package of fertilizer, usually on the front. You'll see 10-10-10, or 15-30-15, or some other combination.

You don't want to overdose on the nitrogen in flowering or fruiting plants because that will stunt, or delay blooming. Your mom is partly right about not fertilizing Morning Glories - all plants need food, but Morning Glories are adapted to poor soil conditions and need little additional fertilizer. If you fed them something like 20-10-10, then youlll not get very many blooms, but if you fed them a bit of 10-30-10, then you would be encouraging more flowers. Using that knowledge, you can guess that Hostas would like a higher nitrogen (N)fertilizer, and tulips would like one with a nice amount of potassium (K)and phosphorus (P). Tomatoes are fruiting plants so need lots of everything, but prefer more P and K than N.

So, know what you've got and use it for the plants that need that sort of fertilizer, and get a different sort for your other plants.

If you want the best possible fertilizer to use on just about everything, start a compost bin. You get free fertilizer that way and your plants will prefer it over Miracle Gro any day. Use the money you save from not having to buy fertilizer to buy more plants!

BP

I agree with BP, For me the best fertilizers are the compost, composted manure, bone meals, blood meals, etc.. To create a really lush looking garden, these are all you need and you'd only have to apply it 1 -2 x every year.

Ianna

It's true about Morning Glories. Unless you LIKE humongous foliage and hidden and/or nonexistent flowers, refrain from fertilizing. They PREFER poor soils.
Can't agree more about the REAL fertilizers mentioned above. I mix composted sheep manure and domestic compost in with the fragmented rameal wood mulch and voilà .

Two more that do not like chemical fertilizing are the hydrangea and the peony. A handfull of compost is better tolerated.

Those Miracle Gro sprayers are good for container plantings with petunias, marigolds, pansies, etc. and the same plants if you don't have great soil or compost, which not everyone does. Plus it's pretty safe and foolproof Not everyone is going to get down and get all "earthy", they just want a nice pretty looking flower bed so I don't feel it's up to me to dismiss a product like Miracle Gro. I'd rather see someone using some Miracle Gro and having a nice flower bed, loving it and the results and moving on from there to bigger and better over the years.

Again, for me, compost and organic fertilizers work best for plants- so if you have poor soil, amend with the above. Organic fertilizers and composte provide nitrogen slowly, as the plant needs it. You'd have to apply it once or twice in a year. Whereas chemical fertilizers are do provide nitrogen immediately but is also disappears quickly which requires more frequent applications.

Ianna

I found my lavender did better with poorer soil (or maybe it's just me :)

raptorfan - some things have evolved to take advantage of poor soil and when you fertilize them they can put out too much foliage at the expense of roots. I killed three lavenders with kindness before I got it through my head to leave them alone :-) Of course part of my problem is that I don't really have 'poor soil'.

pkguy - It's true that not everyone has access to compost. Balcony gardeners in particular, don't always have room for a bin. But where there's a will there's usually a way. I live in a ground floor flat in downtown Montreal. It's a concrete jungle - my backyard is paved and I can't dig it up because I rent. All my plants are grown in containers - everything from Impatiens and Geraniums to Ostrich Ferns and Daylilies, from Cannas and Callas to tomatoes and asparagus. Those big black composters that everyone has aren't going to work for me (too big)- so I improvised. I use 2 80 litre Rubbermaid storage bins from Canadian Tire as compost bins (they have holes drilled in them for ventilation) - I manage to produce a whole 80l bin of finished compost every year and an additional 2 bins full of partially finished compost (from the winter months - that gets put in the bottom half of my tomato containers). I do have some 'Miracle Gro' around for emergencies, but I haven't used it in four or five years (I do buy some worm casting fertilizer to use on my houseplants).

I'm more than a bit of a tree hugging hippy at heart, so I believe that I should do whatever I can to reduce the load being sent to landfills, and reduce the amount of chemical pesticides and fertilizers I use. I know that not everyone feels this way, and I don't expect them to. But I also know that many people do feel this way, but don't know all the options they have available, so it's good to give as much information as possible. I'm not dismissing Miracle Gro as a waste of time or money, used properly it will give you a nice garden. But so will other less expensive and more environmentally friendly options. Having more options available is always better :-)

BP

Most of the gentians and alpine flowers do not like any type of fertilizer

Wisteria I believe is another plant that's better left unfertilized if you want it to bloom.

Most herbs prefer poor conditions, like dirt. I used to fertilize. Now I just use a half-inch of compost on everything once a year, and my garden (and grass) never looked so good.

In order to understand fertilizing needs (or no needs) of plants - try to understand the plants origins and that should give you a clue on how to treat them.

Ianna