Garden Talk

with Rebecca Jordi


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Q: My gardenia is not doing well and I am thinking the soil pH might be the problem. How can I get it tested?

Gardenia Flower

Gardenia Flower

A:  Go about 6-8 inches deep and take several samples from around the root area placing the samples in a bucket.  Mix the soil and bring us one sample – about a cup is fine.  Master Gardeners man the Yulee satellite office on Fridays 10am – 2pm and can run a pH for you at no cost.  Call us at 904 530-6351 for directions to the Yulee satellite office.  You can also drop the sample through the letter box on the door and we can run it anytime during the week.

Now, just a few things other things to consider regarding your gardenia shrub:
1.  Gardenias should not be planted by the foundation of a home or near the sidewalk, driveway, or walkways as these concrete structures leach and have a tendency to raise the pH to uncomfortable levels for these acid loving plants.
2.  Planting them under the eaves of the house encourages leaching too and often the plant will get too much water off the roof if there are not gutters.  Too much water can create the prefect environment for disease such as fungal leaf spots and root decays.
3.  Some cultivars of gardenia do better with morning sun exposure and afternoon shade.
4.  Keep lawn grass as far away from any tree or shrub as the things we do to lawn grass we should not do to trees or shrubs.  Be careful about applying lawn grass weed killers around the roots of trees or shrubs.
5.  Keep mulch off the trunk or any tree or shrub.  Allow for an area around the base of the trunk which contains only soil and air.  Mulch should be only 2-3 inches deep.  Never use rock as it can compact the soil and retains heat – neither is good for trees or shrubs.  Pine products are preferred.
6.  It is critical to ensure the shrub is not planted too deeply.  You should be able to find the large roots coming off the trunk in just an inch or so of soil.  More than a few inches of soil on the roots is too deep.
7.  Watering the shrub twice a week like the lawns can be excessive and they hate it.

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Q: Should I prune my gardenias or azaleas now?

Gardenia

Gardenia

A:  This is one of the most common questions I get every February.  So I am repeating my answer from a previous Garden Talk.  Gardenias, like azaleas, would need to be pruned after they have finished flowering, which will be sometime late spring or early summer. The best management practice for most any flowering plant is to prune directly after flowering. If they are pruned now in late winter, then we will reduce the number of flowers produce as the buds for flowering have already been formed. Gardenias and azaleas really require very little pruning except to improve their shape and/or remove broken or diseased stems. It is possible to prune azaleas or gardenias to increase flower production but keep the removal of stems to a minimum. Selectively prune a stem by hand rather than use a motorized pruning utensil. Hand prune the stems selectively by cutting back to a bud and be sure the stems are cut at a proper angle. Cuts should be made about ¼ inch above the bud. It is also best to prune the shrubs so they are smaller on the top and larger on the bottom to allow for the best exposure to sunlight. Remember, gardenias like well-drained, acid, organic soils. It is important not to water them as often as we do lawns. Avoid using heavy rock mulch around the root area as this will cause compacted soil. Consider using pine straw or pine bark as a mulch. Leave an area about 12-18 inches around the trunk with nothing but soil and air, which is an excellent practice for any tree or shrub.  I know everyone is eager to get out and prune their perennials but it is best to wait a little longer until we are certain the fear of freezing temperatures is truly over.