The long-term fertilizer that you use in spring has usually run out by the end of June. Then it’s time to use a short-term fertilizer to help the plants along. This ensures that the growth and the flowering propensity of the plants can be maintained right into fall. At the start of August, however, you should stop fertilizing so that the plants can prepare for the end of the growth period and upcoming winter.
There are many different kinds of short-term fertilizers. Special fertilizers (e.g. geranium fertilizer) have a nutrient combination that is specific to the needs of a particular plant group and are therefore ideal.
If you don’t have room for all the special kinds of fertilizer, or if you just like to keep things simple, then you can use an all-purpose fertilizer. Most balcony, garden, potted or house plants respond well and you will have good results.
Careful with chloride
The main components of an all-purpose fertilizer are nitrate, phosphate, potassium, magnesium oxide and sulphur. If an all-purpose fertilizer contains chloride, then take special care because chloride can damage many house and garden plants. If you use it at all, then be sure it is present only in trace amounts.
By the way: Passionate gardners can tell from the specific signs of deficiency which nutrient is missing.
Rules for fertilizing plants
Liquid fertilizer works the fastest and is the easiest to use. These (and also other kinds of fertilizers) should never be applied to dry soil. It is also better to fertilize more often in smaller amounts, than seldom and in high doses. The best method is to follow the instructions for the amounts on the package. And, something else: During winter (usually August through March), you should not use fertilizer at all.