History of MRS
MRS Public Garden
Bronze Medal Awards
WHEN AND HOW TO DO IT
by Nanette Londeree, Master Rosarian
How About Seaweed?
Harvested from the ocean, the marine kelp ‘Ascophyllus nodosum’ (not the kelp that washes up onto the beach) is the most common form of seaweed available as fertilizer – it comes in liquid, powder, meal or pellet form. In addition to a little nitrogen and potassium (1.5-0.5-2.5), it adds valuable trace elements, growth hormones, and vitamins that can help improve overall plant growth and reduce plant stress from drought.
How you apply fertilizer depends on what you are adding and when. For granular, powder or pelleted-type fertilizers, scatter them around the base of the plants and scratch lightly into the soil. Water-soluble products can be simply mixed in a watering can and applied directly to the plant, or if you’re fertilizing a larger number of plants, you may want to try a delivery device – ones that add concentrated liquid fertilizer to water at a specific rate. Called proportioners, they can be a hose-end sprayer with an adjustable dial that indicates the concentration of fertilizer you’re adding per gallon of water, a siphon device or an automated metering device. The siphon is a simple device with a connector that attaches to your water faucet and hose. It has a plastic or rubber tube connected to it; the unattached end is immersed in a container with a concentrated solution of water-soluble fertilizer. When you turn the hose on, the water pressure draws up the concentrated solution and mixes it with water to dilute the fertilizer as you apply it to your plants. The metering device functions in a similar way and can be added to your automated irrigation system to deliver a desired concentration of fertilizer every time you water.
The fastest route for providing nutrients is through the leaves - spraying a dilute solution of fertilizer directly on the foliage. Plants can absorb nutrients 8 - 20 times more efficiently through their leaf surfaces than through their roots. When using the foliar feeding approach, use a surfactant such as a mild soap (1/4 teaspoon/gallon of spray) to ensure coverage of the leaves, otherwise the spray may bead up on the foliage. Any application system that can provide a dilute liquid to the leaves will work (watering can, hose-end or backpack sprayer, etc.). Use a fine spray and spray until the liquid drips off the leaves. Also spray on the underside of the leaves where pores are more likely to be open.
If you’re growing roses in pots, use your solid or liquid fertilizer at one-half strength twice as often as roses in the ground, as watering flushes the fertilizer from the potted soil more quickly. Remember to water the rose well the day before fertilizing so there is less chance of burning the tender roots.
Finally, be gentle with your miniature roses, they can be sensitive to chemical fertilizers, so it’s wise to fertilize them at half-strength.