What is the best food to add for watering?



What is the best food to put in your watering can
to feed your house plants , such as Geraniums

yes what is the number that i should buy and brand ?

could you let me know



A simple question, unfortunately not a simple answer as the fertilizer requirements for your houseplants will vary, depending on a number of factors, including

  • the particular plant
  • its growth habit (whether it is dormant or actively growing)
  • its growing conditions (including the soil that it is growing in, the size of the pot, and the light conditions)
  • what you are trying to achieve by giving the plant “food”.

In general terms fertilizer is applied to a container grown plant to supplement the nutrients in the soil that the plant is growing in, as unlike plants growing in natural conditions in the wild, a houseplant cannot extend it roots to seek out the nutrients that its requires for healthy growth from its environment.

The three main chemical elements required by plants for healthy growth are:

  • nitrogen – N (which promotes growth in the leaves and shoots of the plant)
  • phosphorus – P (which promotes growth in the roots)
  • potassium – K (which promotes the growth of fruit and flowers).

The mix of NPK will be indicated on the label on the fertilizer, i.e 20-20-15, or 19-31-17 or 2-7-7- (from the houseplant fertilizers in my cupboard).  While a balanced fertilizer is often appropriate for houseplants, the mix of these three ingredients in the fertilizer you should give a particular houseplant may depend on what you are trying to achieve.  In the case of a flowering plant a higher percentage of potassium is advised; if it is a plant that is only leaves, then a higher percentage of nitrogen may be advisable.

Note that in determining whether to fertilize a houseplant you should also consider its growing conditions.  For example if a plant is in a low light situation, especially during the winter months, it may only grow very slowly and will be able to get all of the nutrients that it needs from the medium that it is growing in without any additional fertilizer.  However, a plant in bright light and actively growing, may be using up the nutrients in the soil in which case it should be fertilized to promote continued growth.  Similarly, a cactus which is watered only very infrequently will need less fertilizer than a plant which is watered much more often as in the latter case watering is likely to cause nutrients to leach out of the soil which will need to be replaced.  Note that as there is a risk of over-fertilizing, which can be deadly to a plant -it is better to err on the side of too little, rather than too much fertilizer.

In this link  is a detailed article on fertilizing houseplants which you may find helpful.  Among other things, it discusses the different types of fertilizers and why you might choose one type over another.

Geraniums (Pelargonium), which you specifically asked about in your question, generally require a fertilizer which is high in phosphorus and potassium.  I suggest you look at Pelargonium (Geranium): A Toronto Master Gardener Guide for  detailed discussion of how to grown geraniums.

As Master Gardeners we do not recommend particular products.  However, once you have determined what you are looking for, staff at your local nursery should able to suggest the appropriate products to you.