Hi,
I have a bag of Grow More 6092 Sea Grow 4-26-26. I am wondering if I can use for my outdoor container fruit trees (sweet cherry, peach, pomegranate)? Low N is trying to control the vigor of plants. If 4-26-26 is not a good choice, what would you recommend?
Thanks
As a one-time application in the Spring, yes. For year-round application, no – instead I recommend Grow More Fruit Fuel 16-8-24.
That is accomplished by concentration of the fertilizer in water, not by the water-soluble formula itself.
I don’t think that is a good formula for any fruit plant, but requirements do vary from species to species. Osmocote makes as good a slow release fertilizer as anyone and I’m looking at a bag with 15-9-12 with a wide range of micros which is their all purpose 6 month formula.
While this may not be right for you plants, I am skeptical that your extremely low N formula will serve the needs of your trees. Are they suffering from excessive vigor? I’ve never had that problem with container trees- the constriction of the pot tends to encourage fruiting at the expense of vegetative growth.
You don’t need low N to control vigor in a pot. The small soil volume does that on it’s own. In fact in a pot I’d say you need a high N fertilizer because the N leaches right out. The formulas recommended above are about what I use.
What limits tree size in a pot isn’t so much fertilizer or roots it’s the low amount of water that the tree can extract. The tree can extract only so much water each day unless you run water all day. How big can a tree grow when limited to 1-2 gallons of water a day, not very big. When the tree reaches the max size it can achieve on the limited water available, vigor falls off a cliff. At that point pruning both the top and roots will be needed in order to grow new fruiting wood. Vigor on my trees in 12 gal pots declines dramatically about yr 4.
One of the rules of gardening: Just because you have a lot of something, that doesn’t mean you should use it. 
(I’m guilty of this too.)
this is sage advice…
I had a few trees in 15 gallon container this year, they were on drip with 2 gph emitter and I watered them 30 or 60 mins between June till August three times a week. Reading you comment it seems they would need more water than what I supplied this year. Except one Hollywood plum which showed water stress during the late July and August, the others looked ok with the amount of water. For next year, I am thinking about replacing the drip with spray stakes which can apply 3-10 gph.
Do you have insights on some calculated approach on how much water does a container grown tree needs per day or week as it grows from a bareroot tree which I believe are typically one year old when they come out of the nursery. In my case the tree will be in well draining potting soil comprising of peat, bark dust/mulch, coarse pumice and some compost.
I don’t know how to calculate water use for a potted tree. I’d say it’s trial and error. You want some water to drain thru the pot so as to avoid salt buildup in the media. Maybe 10-20% of what’s applied should run thru.
It’s always a moving target. Water use will vary depending on tree size and weather conditions. One day may be twice the next day. Midsummer may be twice early spring, etc.
Drip irrigation is not effective for most fruiting plants. The volume of harvest is proportional to the volume of roots, and therefore you want to develop a large canopy of roots around the plant. Drip does not do this. Install at least two 1/2 inch risers with streamer-type shrub heads per plant. The goal is to completely saturate the mulch each time the water comes on. The frequency of watering depends a lot on your local climate. Consider these degrees of wetness, from most to least: soggy, wet, moist, less-than-moist, dry. Most fruit trees like moist soil. If the soil stays soggy they will rot, and if it stays dry they will wither. After each watering, the soil should be temporarily wet and then after several hours (or a day) drain to moist. When the soil at the root depth becomes less than moist, it is time to water again.
The pot which dried out often came with potting mix from nursery it drains great (1/4" bark, perlite) and has less peat-moss. Other two trees are in root builder pots but I have used good amount of peat which probably helped.
I have these spray stakes in various flow rates and it has worked well for my blueberries where I have 2 to 6 such stakes. I think for container trees I can install one or two per pot (15 gallon).
For trees that are in ground does this make them not to root deeper and just grow roots at the surface along the mulch ring which in my case is 3 or 4ft per tree.
If it does then there is something wrong with your planting hole and/or watering frequency.
Notice that I said:
Regardless of what sellers might call them, spray stakes are not drip.
I agree they are not “drip” when they put out 10 gallons in 30 mins, I like them because they are can be more targeted vs sprinklers.