Susan Handjian is a garden educator in the San Francisco Bay Area. She was a contributing editor of Plants and Landscapes for Summer-Dry Climates.
By: Susan Handjian , 9:40 PM GMT on April 07, 2013
As all gardeners know, a trip to the nursery is full of enticements. Everything looks so lush and beautiful, and if a four inch pot of lavender looks nearly perfect, then a one gallon pot of the same plant must be even more desirable, right? Not necessarily. It’s perfectly understandable to think that bigger is better, but that may not always be the case with plants. There are some things to think through.
I have looked everywhere for an article from a long ago issue of Sunset that had a profound influence on my thinking about plants. It’s now tucked away in a special place (in other words, it’s most likely lost), but I remember its lesson vividly. It compared the growth of a perennial sea lavender from a six pack, a four inch pot and a one gallon pot. At the end of a full growing season, the plants from the six pack were about half the size of the four inch, and the plant from the four inch was as large as the plant from the one gallon container. The article explained that while the plant from the one gallon was larger than the four inch specimen, it was also older and therefore experienced some shock that the younger, smaller plant did not. It was ready to take off the moment it went into the ground.
This same outcome is even more pronounced when a one gallon plant is compared to a five gallon plant. The plant in the larger container could be several years old, quite content to be growing in a rich medium, while the one gallon plant will be much younger and with far less room for its roots to be comfortable. The proof is when these plants are actually put into the ground. All other things being equal, the larger and older plant may endure a prolonged period of shock and adjustment after planting, while the younger, smaller plant is ready to take off and get growing.
There are several lessons to be learned from these experiments. When there are good looking specimens of the plant you want in four inch and one gallon containers, the four inch is your best bet for quick results. It is also your best buy. At some nurseries you can buy two 4 inch pots for the price of a single one gallon pot. That’s a bargain that even instant gratification can’t compete with. As a bonus, I also find the four inch pot the easiest size to put into the ground.
Here are some sizes and types of plant containers you can most readily expect to find at the nursery, although I’ve noticed in the past few years the emergence of 1 quart and 2 gallon pots as well as some two and four inchers made of recycled materials and of coir, or coconut fiber, and peat.
Here's a general idea of what plants you'll most likely find in what containers:
Six pack: herbs, vegetables, annual bedding plants such as impatiens, and some ground covers
Two and four inch: vegetables, annuals, perennials
1 gallon: some annuals, perennials, smaller shrubs
5 gallon: some perennials, shrubs, smaller, younger trees
15 gallon: large shrubs and young trees
24”, 36” and 48” boxes: trees
Roots: The Heart of the Matter
Before you make your purchase, take a moment to discreetly peek at the rootball of the plant. Gently turn plant out of container enough for you to get a good look at the root system. You’ll see one of three things: 1) beautiful, healthy rootball with white roots reaching to the outside, just holding together the mass; 2) mostly soil, few roots, or 3) mostly reddish or brown roots and little to no soil, meaning the plant is rootbound.
If you’re fortunate enough to find the fresh, healthy rootball, off to the cashier with you. There’s nothing more to be done except take your treasure home and dig a hole.
If you discover an underdeveloped root system, the plant has probably recently been moved up to a larger pot and needs more time to develop. That plant has to go back on the shelf for a few more weeks.
The rootbound plant poses several challenges. In six packs and 4 inchers, you can be pretty rough. It’s not uncommon at all to see gardeners take a tiny plant from a six pack and pull the root system apart about halfway up, then plant. Some rootbound four inch pots will have even taken on the shape of the pot. Pull those compacted roots away and toss them in the compost pile, and then score the sides gently with a sharp, clean knife. That will stimulate new root growth and get the plants off to a faster start. See below how some rootbound six packs were liberated prior to planting. Although the treatement looks harsh, these plants now have a new lease on life.
Unless you are willing to take action to help it, a severely rootbound plant is doomed. Confined roots don’t have the capacity to absorb moisture and nutrients from the soil once planted, and even a warm day will cause such a plant to wilt and even die before it becomes established.
The rootball itself is a solid mass of roots growing around and around until it becomes girdled. Once extricated from the pot, this mass must be cut and scored with hand shears and a knife, even pulled off the bottom. Sometimes roots can even be seen growing out the top of the container.
A nurseryman whose opinion I value highly advises removing all the soil from such a plant by hosing off the root system, trimming and teasing the roots, then planting as if it were a bare root specimen. It seems quite radical at first, but I do believe his claim that a girdled root system may never allow moisture to reach the center of the underground root mass, leading to the heartbreaking death of plants during hot spells.
Full Bloom: To Buy or Not to Buy
One final thought. As enticing as blooms can be, don’t buy a plant in full bloom if there’s another specimen nearby that has only buds, or even better, lots of healthy green top growth and just a few buds beginning to develop. Allow the plant to have its first bloom in the ground, not in the pot. A plant that is blooming in a nursery container has invested tremendous energy into blooming and will have little left to develop roots. It is already stunted. Growers fertilize plants heavily and even put plants under intense lighting before sending them to market in order to bewitch the unsophisticated, but more educated and savvy customers now realize that blooming in the pot is not desirable.
Have fun at the nursery!
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