Connecting the Dots – Soil, Water, Fertilizer & Nutrition by Mike H.

Thursday, June 4, 2020
Throughout my career, I’ve always said that “no two springs are the same”.  While indeed correct, this is truly an understatement concerning the spring of 2020.  This Covid pandemic has changed us and the way we do things.  It will also affect what we do in the future while taking us to a new normal, the extent of which remains to be seen.  I just hope that, in the end, people emerge from this appreciating the simple things again such as plants, flowers, and nature in general.  It’s amazing what plants can do to make one feel good.  As vacations are cancelled and families are forced to stay home, the appreciation for plants and nature, in general, will take on renewed importance in the lives of many,  hopefully on a permanent basis.  I’m hoping that we’ll now take a break,  slow down and be kinder to the environment and to one another as we move forward.
Throughout my career, I’ve always said that “no two springs are  the same”. While indeed correct, this is truly an understatement  concerning the spring of 2020. This Covid pandemic has changed us and  the way we do things. It will also affect what we do in the future while  taking us to a new normal, the extent of which remains to be seen. I  just hope that, in the end, people emerge from this appreciating the  simple things again such as plants, flowers and nature in general. It’s  amazing what plants can do to make one feel good. As vacations are  cancelled and families are forced to stay home, the appreciation for  plants and nature in general will take on renewed importance in the  lives of many, hopefully on a permanent basis. I’m hoping that we’ll now  take a break, slow down and be kinder to the environment and to one  another as we move forward.
 I know you all were forced to respond to this in many different  ways regarding the closing of schools, initiating on-line classes,  conducting plant sales, etc. Even within states, school districts varied  drastically in their responses regarding staff access including, in  your case, greenhouse upkeep and plant sales. Some of you were forced to  dump your plants and others were allowed to follow through with your  plant sales with limitations and special precautions in place. Many  initiated a digital ordering system where plants were presold and set  aside for customer pick-up. Others had more traditional plant sales with  personal distancing set in place. Some offered to wholesale plants to  local garden centers and retailers. Some donated everything to community  efforts. It was both interesting and inspiring to see how this  situation was handled across the country.
 One thing that I did notice throughout all of your correspondence  was the determination to make any and all efforts necessary to find a  home for the plants. Of course, it didn’t work out for some. Some of you  bent rules to keep plants and hope alive as others were given more  freedom. And, of course, all while working from home, often with your  own kids underfoot needing attention and guidance at the same time. What  a year! You all amaze and inspire me. Thanks to all of you who shared.

Connecting the Dots – Soil, Water, Fertilizer & Nutrition

 As is usual in spring growing seasons, I received quite a few calls  and emails pertaining to insects and nutritional concerns. Growing is  indeed a challenging vocation. The plant breeders as well as soil,  chemical and fertilizer manufacturers all do what they can do make our  job easier by providing ready-to-use, quality products to help us be  successful. For this reason we can often get away with being a bit  complacent (aka: “busy”) especially in the chaotic, overlapping worlds  of work and home that we now live in. Plants are bred to grow better,  stronger and with more flower-power while, at the same time, being more  resistant to diseases, poor weather and less-than-favorable growing  conditions. Better quality growing mixes provide mediums that buffer  against the higher pH of most waters. Fertilizer manufacturers put  together a feed package where all we have to do is basically add water.  This is all great but can cause us to sometimes forget how the soil,  water, fertilizer and the choice of plants all work together to produce a  successful crop. We then risk not knowing what is taking place when  problems develop.

Soil Mixes:

 Most greenhouse soil mixes are primarily peat and perlite-based. A  good soil buffers pH is porous (provides air to the roots), and holds  water well. All commercial mixes are closer to one another than you  might think. Don’t agonize about which one is the best to use. Just  choose a good quality commercial mix (I strongly recommend Pro-Mix or  Berger) for your general growing purposes and become familiar with it.  Be sure you rotate your soil and use it within 8 months after receiving  as the wetting agent in all soils will wear out over time. The purpose  of potting soil is to stabilize the plant and provide a medium from  which plants can draw water and nutrients. Other than a small starter  charge of fertilizer, artificial soil mixes offer no nutritional value  for your plants. This will need to be added. Your commercial soil mix  will have a pH of about 5.8 to 6.0 which, due to its buffering  abilities, help to keep the pH near the level your plants need in order  to take advantage of the nutrients made available to them.


 All plants need water. You should know your water to the point where  you are at least aware of its pH and EC, allowing you to then formulate a  fertilizer regimen for your crops. Most municipal waters have a pH of  about 7.6 to 9 which is alkaline due to the chemicals they add to slow  corrosion of distribution pipes. The pH of your soil and water and how  they are related is very important. Again, the fertilizer and soil  companies strive to make growers successful by making their products  work towards maintaining a soil pH of 6 which is ideal for most plants.  You not need to concern yourselves with the complexities of the chemical  interactions that take place in the soil. You just need to target that  ideal pH so your plants do what they’re programed to do. How do you do  that? Easy, use a good quality, peat based growing mix and try to  fertilize with each irrigation which will help keep you pH down in that  plant friendly zone. It’s when you use clear water out of the tap that  the pH tends to drift up to where nutrients, even though present in the  soil, cannot be utilized by the plants.


 Please don’t underestimate the importance of using a proper  fertilizer. Just like people, plants need to be fed. Essential to their  well-being are the macronutrients: Nitrogen (N), Phosphorus (P) and  Potassium (K). Also necessary are secondary nutrients such as Calcium,  Magnesium and Sulphur as well as micronutrients which include Zinc,  Iron, Manganese, etc. These nutrients are also needed in the correct  concentration and ratio to one another in order for plant growth to be  optimal. As complicated as this may seem, fertilizer companies have  already done all this work and have put the results into handy 25# bags  for us to pour into our stock tanks and feed our plants. If used at each  irrigation, your pH should remain relatively stable throughout the  length of the crop and plants should be well nourished.
 If you use just tap water to irrigate your plants, this will  challenge the buffering capacity of your soil and the pH will eventually  creep up to where you’ll notice nutritional issues with spring annuals  and many other plants. That interveinal chlorosis on your petunias and  calibrachoas is the first indicator that your pH is creeping up to where  some secondary and micronutrients may not be available such as (in this  case) iron. Use commercial fertilizers that have all the nutrients  needed for your crop and that help buffer your water to keep your pH in  that safe zone. In my opinion, 20-10-20 is the best general purpose  formulation unless water tests have indicated otherwise. This is a high  nitrate based nitrogen fertilizer which is much better for growing in  peat based media than the too often used 20-20-20 which is high in  ammonium and urea nitrogen. The 20-20-20 works well for keeping things  green on a maintenance level but not for growing, especially in a peat  based soil mix.
 So, how do you know what your soil pH is? The best method is to use a  pH meter. pH pens are very inexpensive and give very accurate readings.  You can also get a ballpark figure by measuring the pH of the water  (leachate) that drains from the bottom of your pot. Collect the leachate  and then use the pH strips for aquarium or pool to find out if your pH  is in the target range. It is much better to have an actual pH meter  that, if used on a routine basis, can show changes in the soil pH which  then allows you to prevent a problem rather than treat it. This can also  make for a great class project.

Mum Primer:

 For those of you growing mums, your rooted cuttings should be  arriving this month.  Here are just a few quick pointers to get the most  out of your crop.  Remember that if things have gone well for you with  past crops, please don’t shift and do anything drastically different  because of something I mention here.
  • Plant liners immediately upon receiving.  For largest plants, schedule them to arrive the first two weeks of June.
  • Use  a bark mix or one that has a coarse peat moss and is very porous.   Porosity and air to the roots is important.  The soil needs to both hold  water and drain well.
  • Growing mums outdoors is best.  If you  see stress or slight burning of the leaves after planting they’ll  quickly cover up with new foliage
  • Fertilize immediately and with  each irrigation after planting.  Mums are heavy feeders.  Use 20-10-20  early in crop.  You can finish with this formulation or you can switch  to a 22-5-16 Mum Feed later in crop which hardens off the crop prior to  sale and keeps the necessary iron and other micronutrients available to  the crop even if the pH rises during the crop cycle. 
  • Keep feeding throughout crop with each irrigation if at all possible.
  • Avoid using sprinklers.  Drip irrigation is best to prevent foliar diseases from developing.
  • Never  let mums dry out or wilt.  This stress will weaken them, risking stem  breakage later in the crop.  This stress can also cause premature buds  and flowering.
  • Most mums today don’t require pinching.  For them  to do their best they need to be pushed with heavy fertilization to  promote lateral branching leading eventually to a well-rounded finished  plant.  Your fertilizer protocol in the early half of the crop will help  determine the final size of your crop.
  • Be vigilant and watch for caterpillars and aphids.  Marathon is a good systemic preventative for both.
If you’re doing something different  in your greenhouse than is shared above and all is going well, please  don’t change. Perhaps modify, experiment and consider but be cautious  before changing a good thing. Successful growing is the result of many,  many variables. Some we have control over and some we don’t. The above  is only meant as a guide or checklist prior to the upcoming growing  season.
If you need help or elaboration on any of the above topics, please feel free to contact us.  If you need a source for or advice on annuals, perennials, pH or EC  meters, soil or anything else, I can help you with that as well.

Happy Growing!

 Mike Hellmann
Plants and Cuttings Manager

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