Newfoundland Horticultural Society

 A ROSE GROWER'S PRIMER – IV

by  Harry McGee ©National-Roses-Canada 2009 

In the last three issues, we discussed (l) how to match the time you have available with the kinds of roses you choose to adopt, (2) where to position them and how to give them a deluxe planting, and (3) how to winterize the tender ones.

Now we will talk about caring for roses in the time between spring planting (or spring uncovering) and winterizing them when the growing season ends.

If you made an honest decision that you have a very limited amount of time to mess with roses, yet you love the blossoms, the colour and the fragrances, you have planted hardy roses that are resistant to diseases and pests. You will not have to slave over them fighting disease and pruning them. They will get along pretty well on their own.

However, all roses need food and water. That pail of water you put on your rosebush when you planted it won't last long. Your roses need plenty of moisture but not wet feet. Any area of the country may have a period of drought - some more regularly than others. So buy a rain gauge and monitor how much rain falls. Why a gauge? Can't you tell how often it rains and act accordingly? Maybe, but rains can be deceptive. It might be a light rain, little more than a drizzle, and on again off again. On the other hand, it might be a soaker; a steady all-day rain with big loaded drops - the kind a farmer calls a million dollar rain. Unless you are out in it, you cannot tell. But a rain gauge can.

Roses need a minimum of l inch (25 mm) of water every week. If nature doesn't provide it, then you must. Do it early in the morning so the roses can dry off before the heat of the sun or the arrival of night. Wet leaves, especially at nightfall, invite fungus. Watering at the ground surface or below ground is acceptable at any hour. Don't let one week go without water. If you are going to be away for a week or more, ask a friend or hire a garden maintenance company to do the watering for you. And remember mulching conserves water. So does weed elimination.

Some people have little tricks they employ to optimize the water applied to the roses. They make the soil around the rose plant contoured like a shallow dish. This causes water to remain collected around the plant rather than run off toward something else where there are no rose roots.

When it comes to food, don't add any chemical fertilizers to the rosebushes you planted this year. Remember the good things you planted with them had a supply of composted cow manure, a handful of bone meal and plenty of compost. That is enough for the first year.

For subsequent years, or on established plants, you can't beat cow or steer manure (some folks prefer sheep). Great stuff. If you buy it as wholesale farm manure, it must be guaranteed to be three years old or more so it won't bum and won't smell. Unfortunately it comes with weed seeds. Manures are also put up in bags by commercial firms and available under trade names like Moo-Poo. For small gardens, that is practical. Some people have access to fish food, which is reputed to be very good if used according to instructions. Unless you are very savvy on the dangers of mushroom compost, stay away from it. In wet climates it may have been rain-leached of harmful salts, but it is a gamble not worth taking. No two mushroom producers use the same mixture of soil and fertilizers, and I can speak from experience that some will bum rose roots with lasting effects. Poultry manure, even composted, is generally too hot to put on roses.

If you want to go to chemical fertilizers, it is important to get counsel from your local rose or horticultural society. People there will understand your soil composition and what ingredients to avoid and which are needed. For example, in many places on the prairies, it is important not to include any potash in fertilizers applied to soils that are already loaded with K.

Whether you use natural fertilizers such as composted manure or chemical fertilizers, it is important to get your soil tested before you apply any of them. This will give you a clue as to what type of mix to use. Then have it tested again from time to time so you can see if it is changing. I once discovered that I had been feeding my roses too well and had built up a surfeit of potassium and potash. I had to plant root vegetables among my roses to sop up the excess K and P. Some agricultural suppliers will counsel you on what products are best to deal with your soil analysis. There are products such as K-mag, which add magnesium to soils lacking Mg. If you do not avail yourself of such products, you will have to add Epsom salts each year early in the growing season to provide the element.

The late Jerry Twomey told me that roses never get enough iron. It is well known that Rugosas need more iron than other roses to keep them from becoming deficient and exhibiting chlorotic leaves. Mr. Twomey was certain that roses typically lack adequate iron chelate to perform optimally. As a matter of policy, this journal leaves it to local rose societies to advise on local feeding needs, so it always insists that you contact your home society to get counsel. For older gardens inquire about micronutrients.

Wherever you are, it is important to know that the last feeding of any fertilizer comes at the end of July. Then nothing! The rose must be allowed to prepare itself for winter, harden off and stop sending up tender new canes. Discouraging new growth also means starting to ease back on watering - more and more as the growing season draws to a close.

Now comes the part that deals with the tender roses that need all that extra care; the kind that you were advised to avoid if you had limited time to spend in the garden. These are the roses that rose show addicts prize for their multi-petal forms and vie to beat all rivals at winning prizes. It would suit them well to have only tender exhibition roses in the competition. It is true they come in mouth-watering confections, but the price has to be paid in labour.

Let us start with deadheading and pruning. Deadheading means pruning off faded rose blooms or clusters before they become unsightly and take energy making hips (rose seeds). It is important if you wish every bit of energy to go into other blooms. The sophisticated insist you must prune spent HT flower heads back to the first five-leaflet leaf having an outward facing bud in its axil. This is to encourage outward growth allowing sun and air into the middle of the bush. For floribundas, the counting isn't nearly as important. Strong growers produce growth buds at a higher level than HTs, and cutting the top leaves off just reduces the food supply unnecessarily. Minimal pruning is required for climbers, minis and shrub roses - just enough to remove unsightly dead flowers or to shape the plant.

In the 1990s the British debunked all the precision pruning by running some experiments in which hedge trimmers were used to prune roses. They found no reduction in amount of bloom. Of course this would not do if the show bench were the destination for the roses. It was done no doubt to show there has been excessive preaching on how everything must be done. Use common sense.

It is good hygiene to prune out all twiggy growth at the base of all plants. Such twigs have no motive in life - they get little sap, their leaves weaken and are first to succumb to black spot spores, and then act as a springboard for infesting the whole bush.

In the next issue, we will deal with the most controversial aspect of caring for roses: protection against disease and pests.

By permission of the author  .   .   .  HM