Question
Dear Ken:
(Nice name, by the way).  I used to use a fertilizer from Spring Hill Nursery. It was a 5-10-5 plant formula.  I ualso used a 20-10-5 for hedge plants, which I acidentally planted in the shade at the time.  Ooops.  I am now using Miracle Grow, which I think is a 15-10-15.  Sort of your standard Miracle Grow product.  I use it on all my flowers (lillies, astibles, monardas, phlox, hydrangeas, ferns, penstemons, zagrebs).  Which fertilizer would you recommend for zone 6.  My soil, shooting from memory, is slightly acidic, but I am able to change the soil with lime and peat..Ive never had a soil problem.


Thanks,

Ken

Answer
Fertilizers come with 3 numbers: N-P-K such as 10-15-10, or 15-30-15. The latter, is a very common flowering fertilizer formular (including miracle grow, etc).

The N-P-K numbers indicate the amount of nutrients in the fertilizer. A 5-10-14 fertilizer thus contain 5% nitrogen, 10% phosphorus, and 14% potassium. The fertilizer ratios are always listed in the same order: N (nitrogen) - P (phosphorus) - K (potassium).

The size of the numbers are not as important as the RATIO (internal relationship). E.g. you can use a 5-10-10 fertilizer or a 10-20-20 fertilizer. It does not matter. You would just have to use twice as much of the first (or only half as much if using the second). These two fertilizers would be considered the "same type" .. in this case a 'flowering type' or 'fruiting type' fertilizer.

Compare this to another "type" such as 29-3-4, 33-3-3, 20-2-2 etc. These fertilizers are "high nitrogen" (or lawn) fertilizers. They have low phosphorus/potassium and high nitrogon. You can also use a 10-0-0 fertilizer for lawns but would then just have to use more product because the percentage (strength) of the nitrogen is only about 1/3 of the previously mentioned types.


I recommend using balanced fertilizers such as 10-10-10, 14-14-14, 20-20-20 for most garden plant purposes.

Another option is to look for tomato type fertilizers such as 5-10-10, 10-20-20, or 9-12-12, etc. These contain less nitrogen and more phosphorus/potassium. They are generally best for flowering plants and fruiting plants. Other good choices are the high phosphorus types: 10-15-10, 15-30-15, etc. These ratios ("types") are all good for flowering plants.

Plants with foliage (green plants) can be fertilized with 20-10-10, or just 10-10-10 etc.

All would do good with above choices. Miracle grow is a common and usefull fertilizer. Miracle grow is one brand name, however, and they make different "types" of fertilizers, so look at the N-P-K numbers carefully.

For the hydrangeas, I recommed Miracid (a version of miracle grow) but formulated for acid loving plants. If the hydrangea you have is one of the mophead types (pink/blue) then using miracid will help keep it blue. For these plants, I actually prefer HOLLYTONE (by a company called Espoma). It is commonly available and is a very good organic alternative.

While the before mentioned choices are all excellent for flowering type plants (5-10-10, 10-10-10, 15-30-15, etc),
in early spring, a 20-10-10 formular or similar can also be used on flowering perennials and shrubs. This is because perennials and shrubs must put out a lot of green leafy material (foliage) at this time. Higher nitrogen levels at this time help them grow properly. Later in the season, it is better to use 5-10-10 etc since phosphorus/potassium is then more important and too much nitrogen at this time can lead to lush green leaves but little flowers.