Starting Bare Root Roses in Containers
By Robert B. Martin Jr., ARS President
January is the time to start bare root roses in the Southwest and information abounds on how to plant them in the ground. But there is a better way to start a bare root rose – in a container. Most people are not even aware this is an option but it is and it is the way I start all of my bare root roses. So let me explain why in case you’d like to do the same.
The advantages to starting bare root roses in containers are many and include the following:
Roses are particularly susceptible to differences in microclimates, which means simply that a rose may do better in one place in your yard than in another. Also it is difficult to tell in advance exactly how tall the rose will grow in your yard and whether the color of its blooms will be harmonious with its neighbors. Planting roses in containers provides the opportunity for you to evaluate it in a particularly exposure and then to easily move it to another if that seems useful. In the process you can learn where it will perform best before committing it to the ground. You might also learn it is simply a crummy rose. By starting the rose in a container it becomes a much easier matter to send it to a place that it deserves.
Roses do not like competition from other plants. This is because they are heavy feeders and other plants, including neighboring roses, often deprive them of nutrients and room for their roots to grow. Roses also do not like shade and planting a new rose between established roses often results in the rose being deprived of sunlight as its taller and more established neighbors leaf out. Planting a new bare root rose in the ground in an established rose bed is like trying to start a new tree in a forest – it is tough for it to ever catch up to its neighbors. However by planting a rose in a container the nutrients can be delivered to the rose alone, its roots can freely develop and it can be placed so that it does not have to compete with its big brothers for sunlight.
Less Soil Problems
The rose literature has for years spoken of a problem called “soil sickness”. New roses may do poorly when they are planted in a spot where roses have grown before. But there is little agreement with respect to the reason for the problem; some blame nutrient loss, others nematodes, and others fungal growth in the ground. Others theorize that the planting spot has been invaded by tree roots or has otherwise become less favorable for a rose. (I personally believe the problem has more to do with the failure to remove all of the old rose roots that have displaced the soil and harbor fungal infections). Be that as it may it is clear that planting in containers provides the opportunity to use a fresh clean planting medium that will assure the new rose will not have to deal with soil problems while becoming established.
It is also clear that light well-aerated soil is the best environment in which to encourage root development. The prime and initial directive for a bare root rose is to develop a good root system. By planting a bare root rose in a container you can use a light planting medium that the roots can easily invade. This is much better than forcing the rose to set its roots in the heavy clay soil that is common to the Southwest.
Also when roses are planted in a hole dug in heavy soil the result will often be the “bathtub” effect. Water applied to such roses does not drain well into the surrounding soil thus leaving the rose in a bathtub full of water. The roots of a rose need oxygen to breathe or they will literally drown. This is why good drainage is so important to root development and it is easy to get good drainage in a container.
Another advantage to starting roses in containers is that it is easier to care for them. Nutrients and water can be applied more exactly and there is easier access to the entire bush for spraying. The container lifts the rose off the ground, which permits a higher access and the ability to easily turn the rose around. In particularly access to the undersides of the leaves, which on young plants would otherwise be too close to the ground, is improved.
How to Do It
The technique of container planting is relatively simple and can be best understood by keeping in mind the advantages described above. Here’s how –
The key to container selection is to provide the rose with adequate but not excessive room for root development. A rose sets its root system well before putting on much top growth; it is in fact the root system that supports the top growth. Yet top growth should be encouraged as well so that you will have some idea at an early date of what the rose will look like. For large roses the preferred starting container is a 5-gallon plastic container. You can also use a 7-gallon container for a very large rose. Such containers are available for a modest price at most local nurseries; if you are a good customer some nurseries will give you their used containers.
The preferred planting medium for starting roses in containers is light, loose and full of organic matter. I make my own which is simply a mixture of two parts potting mix and one part #2 perlite. The best potting mix is usually something available locally since much of the cost of a potting mix is in its transportation. I currently prefer Happy Frog® Potting Soil from Fox Farm Soil & Fertilizer Company, which has earthworm castings, bat guano, and aged forest products, all said to be alive with beneficial microbes and fungi that help break down organic matter and feed the plant roots. There are many other potting mixes, including various soilless mixes that are commercially available, so look around and find something you like. I do not use soil or compost in the planting medium because it can harbor harmful fungal disease or bacteria.
The bare root rose should be prepared for planting in much the same manner as if it were to be planted in the ground. Soak the rose up to its neck for 48-72 hours in a trashcan or large bucket full of water. I generally add Grow More 7437 Jump Start Plant Tonic, which contains a combination of amino acids, micronutrients, vitamins and “growth factors” in the formula. This is also the place where you can try other magical root stimulants that you may have read about. Whether such products actually work is not certain but I think they may and can do no harm.
Prior to potting up the rose the roots should be examined and obvious broken ones removed. Clip off the end of a few of the fatter ones to promote lateral growth and shorten any that are much too long to fit conveniently in the container. (In this regard you should err on the side of leaving the roots as they are; if you are uncertain about the size leave them alone).
I used to put down a layer of redwood chips or pottery at the bottom of the container in order to prevent the planting mix from running out the holes. I no longer do this because pottery can plug up the holes and the chips tend to rot at the bottom. So, instead I put a layer of pure potting mix, or perhaps a heavier planting mix, at the bottom and tamp it down. You should then add a layer of the planting medium and poke several depressions in it with your fingers. Fill the depressions with superphosphate or bone meal. Use about 1/4 cup of the superphosphate with a large rose. The objective here is to keep the superphosphate in a lump or pile. (There is a possibly good reason for this – phosphates are important to root development but tend to bind to adjoining soil and become unavailable to the roots). Then you should put down another layer of planting mix. Place the rose in the container and arrange the roots in a circle and then fill the container with the planting mix holding the rose firmly at the desired level. Shake the container and poke the mix with your gloved fingers to settle the mix; then add water to settle it further. After the water has drained refill any obvious holes with planting mix and then pour on a gallon or so of the solution used to soak the rose.
Having committed to planting the rose in the container you must plan to keep it in the container until the roots have totally involved the medium. When this occurs the rose can be easily removed from the container with the root ball intact. However if you remove the rose prematurely you will be unable to maintain the root ball and the soil will fall off damaging the fibrous root system that initially develops. As a general rule a rose planted in a container in January should not be removed from the container until early June. At this time it can be easily planted in the ground. More often, I leave the rose in the pot for fall planting or for transplanting to a larger pot. This gives you all the time you could need to evaluate the rose and it is this flexibility that makes starting roses in containers a very useful idea.