5 Ways to Keep Your Garden Healthy

1. Examine plants carefully before buying

The easiest way to limit disease in your garden is to avoid introducing it in the first place. Getting a disease with a new plant is not the kind of bonus that any of us wants. One of the hardest things to learn is what a healthy plant should look like, making it difficult to know if the one you want is sick.

It is a good idea to collect a few books, magazines, and catalogs that show what a healthy specimen looks like. Don’t take home a plant with dead spots, rotted stems, or insects. These problems can easily spread to your healthy plants and are sometimes hard to get rid of once established.

In addition to checking the tops of plants, always inspect the root quality. One does not often see customers doing this in a garden center, but it should be a common sight. Place your hand on the soil surface with the plant stem between your fingers. Gently invert the pot and shake the plant loose. You may have to tap the edge of the pot against a solid surface to loosen the roots from the pot. Roots should be firm, usually white, and spaced all over the root-ball. Dark or mushy roots are not a good sign. Even when the tops appear healthy, it’s just a matter of time before a rotted root system kills a plant.

2. Use fully composted yard waste

Not all materials in a compost pile decompose at the same rate. Some materials may have degraded sufficiently to be put in the garden, while others have not. Thorough composting generates high temperatures for extended lengths of time, which actually kill any pathogens in the material. Infected plant debris that has not undergone this process will reintroduce potential diseases into your garden. If you are not sure of the conditions of your compost pile, you should avoid using yard waste as mulch under sensitive plants and avoid including possibly infected debris in your pile.

3. Keep an eye on your bugs

Insect damage to plants is much more than cos­metic. Viruses and bacteria often can only enter a plant through some sort of opening, and bug damage provides that. Some insects actually act as a transport for viruses, spreading them from one plant to the next. Aphids are one of the most common carriers, and thrips spread impatiens necrotic spot virus, which has become a serious problem for commercial producers over the past 10 years. Aster yellows (photo, right) is a disease carried by leaf­hoppers and has a huge range of host plants. Insect attacks are another way to put a plant under stress, rendering it less likely to fend off disease.


4. Clean up in the fall

It is always best to clean out the garden in the fall, even if you live in a moderate climate. This is not only an effective deterrent to disease but also a good way to control diseases already in your garden.Diseases can overwinter on dead leaves and debris and attack the new leaves as they emerge in spring. Iris leaf spot, daylily leaf streak, and black spot on roses are examples of diseases that can be dramatically reduced if the dead leaves are cleared away each fall. If you are leaving stems and foliage to create winter interest, be sure to remove them before new growth starts in spring.

5. Water properly

Watering your garden is a good thing, but since many diseases need water just as much as plants do, how you go about it makes a big difference. Many pathogens in the soil and air need water to move, grow, and reproduce. To avoid giving these diseases an environment they love, choose watering methods that limit moisture on a plant’s foliage. Soaker hoses and drip irrigation accomplish this. If you are watering by hand, hold the leaves out of the way as you water the roots.

The most common leaf problems are exacerbated when leaves are wet, so overhead sprinkling is the least desirable option. If you choose this method, however, water at a time when the leaves will dry quickly but the roots still have time to absorb the moisture before it evaporates.

Also remember that more isn’t necessarily better when giving your plants a drink. Waterlogged soil or pots promotes some root-rotting fungi and can also suffocate roots, making them easy targets for the rotting fungi.