We do not see signs of Boxwood Blight in the photos, but you can use the information on the linked page (plus our other Boxwood-related pages) to monitor the plants going forward. English and American boxwoods (Buxus sempervirens 'Suffuticosa' and Buxus sempervirens, respectively) are more vulnerable to this and other issues compared to some of the other Asian boxwood cultivars (Buxus microphylla, etc.). If you have a landscape or lawn maintenance company that does not follow best practices to reduce the risk of contaminating their client's yards with pathogens or pests as they move from property to property (you can ask what precautions they take), you may want to educate them on this risk or find a company that is more proactive. Over-pruned (sheared) boxwoods can be more susceptible to infections -- one reason to prune minimally and only as necessary -- and the pruning tools themselves could be harboring infectious spores from another yard.

Boxwood roots grow relatively shallowly compared to most other shrubs and can be more prone to drought stress, damage from planting annuals or bulbs near them each year, or nutrient deficiencies if overwatered. Weekly watering can be good if the plants need it, but make sure you're checking first rather than assuming irrigation is beneficial. Feel the soil around five inches deep (not including mulch, if used) in the root zone of the shrubs and water well only when it's becoming somewhat dry to the touch at that depth.

A standard laboratory soil test will reveal if there are any key nutrient deficiencies but cannot test for pathogens. Roots that are ailing from environmental stressors (too dry, too wet) won't function well enough to pick up all the nutrients the plant needs, hence why over-watered plants can be nutrient-deficient even if the soil itself is not. This is one reason why fertilizing ailing plants is not generally recommended; it might even worsen the situation if soil nutrients are not truly lacking, and it may stimulate growth the plant cannot support if it's already struggling. Soil test results can tell you which nutrients, if any, need supplementing so you don't over-apply others, which can complicate matters with regards to absorption and root health. It can also reveal soil acidity level (pH) in case it needs adjusting, since acidity level also impacts how easily roots can access soil nutrients. Sometimes adjusting soil pH is all that's needed to remedy a foliage nutrient deficiency.

Orange tones in boxwood foliage generally indicate stress, often from environmental conditions, but it isn't always serious or permanent such that it needs addressing. We often see an orange-bronze coloration develop on certain boxwood varieties during winter, perhaps due to exposure to drying winds or freezing soil surface layers depriving the roots of liquid moisture. Sometimes it is associated with boxwood leafminer damage, though we don't see evidence of that insect in the photos.

Mulch is a good insulator for both temperature and slowing soil moisture evaporation, plus reducing weed growth that competes with roots, so we do suggest you leave mulch atop the boxwood root zones. A couple of inches should suffice without being too smothering, though make sure it doesn't contact the stem bases as this can encourage fungal growth or vole gnawing. Manually aerating the soil might not hurt if done carefully (remember, boxwood roots are fairly shallow) but shouldn't be needed if the soil isn't being over-watered and isn't compacted from regular foot traffic. The breakdown of mulch over time, plus any light topdressings of compost now and then (atop the soil, under the mulch) will all improve the organic matter content of the soil, which helps alleviate compaction, which in turn improves soil aeration.

Liquid iron, whether applied as a soil drench or foliar spray, should not be needed unless the soil test results show iron levels are low. Even then, soil acidity may need adjusting instead, since what is present naturally may be enough for the plants if its roots can access it. Iron is a component of chlorophyll which is why applications can temporarily improve the depth of green color in foliage.

Horticultural oil should only be applied when appropriate as the method of suppressing a particular pest. In the case of boxwood, this might only apply to boxwood spider mite (which we don't see damage from in the images) and possibly psyllid. Leafminer is usually treated in other ways, and what fungal spores the oil might smother prior to infection won't be suppressed as well using this ingredient versus labeled fungicides. (While hort. oil is sometimes labeled for fungicide use, it's not the best option. Plus, fungicides act preventatively only, and cannot cure existing infection if present and symptomatic.) Using hort. oil in weather conditions outside of the parameters listed on the product label, such as during high heat, can cause plant tissue damage. We don't see this in the images either, but it's something to keep in mind as one reason to avoid applying a pesticide without a specific indication of need.

Your maintenance company should not need to be regularly fertilizing anything except lawn (and even then, two or three times per year and only according to soil test results for those areas of the yard) and possibly vegetable gardens or fruit shrubs/trees. Decorative trees, shrubs, and perennials typically do not need supplemental nutrients, and decline, lack of vigor, or failure-to-thrive symptoms typically arise from issues not caused by a nutrient deficiency.

Miri

Dear Miri,

Thank you for the very detailed response! I'll need to study it more closely and dissect each sentence! Very good work and we thank you!

Virginia

You're welcome!