Many growers struggle to find the right formula for shrub production. What size liners are appropriate for shifting into what size containers?
This is an important question because time is money. But, at the same time, liners cost money too.
At Spring Meadow Nursery we conducted an experiment to see how different sized liners of different species performed after being planted into 3-gallon pots.
The liner sizes we tested were 2 1/4-inch, 5-inch (quart) and 1-gallon. The shrubs we chose were weigela, itea and carypteris.
Plants were shifted up at the end of February and put in a heated greenhouse here in Grand Haven, Mich. So we did get a two-month head start, but not that great of a head start due to unseasonably low temperatures and low light levels.
It’s more likely that most growers would be potting up these shrubs in late April.
All plants were potted into 3-gallons with standard potting mix and fertilized with a 17-5-12, six-month-release formula. All the plants were trimmed once to give a finished look and to increase branching.
You see the difference
The photos shown here were taken 15 weeks later, just before a second pruning. Depending on how much growing time is available for the grower, all three liner sizes can be used to finish a 3-gallon in one season.
Keep in mind a disclaimer: These timeframes are all dependent on the particular varieties grown, their growth rate and the environmental conditions.
But the 2 1/4-inch liners work great for spring potting, either directly into 3-gallons or by potting them into 1-gallon for a month or two before shifting into 3-gallons.
The quart/5-inch liners (we call them Quick Turn liners) can be directly potted into 3-gallon containers in late spring or early summer to reach the desired 3-gallon size.
Quick Turn liners can also be used to pot into smaller container to achieve a shorter finish time.
The 1-gallon liners can be potted into 3-gallon containers during the summer to reach the desired 3-gallon size, but may require an extra prune to maintain the proper habit of the plant.
So, depending on the amount of growing time available, you can adjust the size of your liner to fit your needs.
Things to keep in mind
In this instance, and with these varieties, it’s important to note:
* Looking at these photos, the 1-gallons that were shifted up were almost too big.
* The 2 1/4-inch liners look fine, especially if they were pruned and given another month.
* The 5-inch liners are practically perfect. They might be a good alternative for growers who feel they’re behind schedule. They’re well-suited for April potting and summer sales or January/February potting for spring sales.
It all comes down to timing and space allocation. For the majority of growers, 2 1/4-inch liners are the size of choice and the most economical. But larger liners might suit your needs if you need a crop finished more quickly.
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- Jeremy Deppe
Jeremy Deppe is general manager, Spring Meadow Nursery Inc., (616) 846-4729, www.springmeadownursery.com.