Let me try this again.

{{gwi:11551}}

Yes they need fertilizer. Givimg a plant fertilizer does not make them " floppy and falling over" Lack of adequite sunlight and getting leggy does that or having too many flowers for the stem to support. You are better off with lots of flowers and staking them to give the flowers support than to starve them and have plants like you have. Check the stores for rings or cages or bamboo poles and velcro tape.

Fertilizer has 3 numbers on the package--

The first number is Nitrogen--It puts the green in the plants. Too much of this is great for lawns but flowers will grow more leaves that flowers.
The second number is Phospherous--This promotes strong stems. It is the key ingredient to make plants grow and mature.
The third number is Potassium--This Helps plants weather extreme weather conditions. It promotes stromg roots and an overall healthy plant.

The easy way to remember this is--green, stems, roots. The best fertilizer for flowers is a balanced one like 15-30-15 or 20-20-20. It comes in granular or water soluable. The water soluable is best for growing flowers. If you use the granular put it around the flowers not on them.

You can also use manure or compost tea, made be soaking either in a large pail with water and using the water to fertilize