The grass has turned green again in our landscaping but everything else is turning brown right? It’s just that time a year. As the temperatures fall there are some things we should be doing to put the garden to bed for the winter.
Cutting Back Perennials– Most perennials should get cut back in the fall. Not only for aesthetic reasons, but also to remove any debris which could be harboring insect and disease pests. Plants such as Echinacea (coneflower) or Rudbeckia (Black-Eyed-Susan’s) can be left up to feed the birds but they won’t be pretty to look at. Some perennials should be left until spring due to poor cold tolerance. There are too many to list here but a few of the more popular ones are:
- Astilbe – Cutting back in the fall may weaken the plant’s tolerance for cold
- Butterfly Bush – To lessen winter kill, wait for signs of green at the base and then cut back to 6-10 inches
- Caryopteris– Newer varieties are especially cold sensitive. Wait until buds begin to green in the spring
- Coral Bells (Heuchera) – Prone to heaving in soils that freeze and thaw. Leaving the foliage intact helps to mulch the plant through the winter
- Gayfeather (Liatris) – Liatris isn’t sensitive to the cold, but it doesn’t like cool wet soil, so if you leave it up it has a better chance to re-seed to make up for any plants that don’t survive. Birds will also eat the seeds
- Lady’s Mantle (Alchemilla) – Lady’s Mantle doesn’t really like to be sheared back frequently. Occasional shearing or removal of dead leaves may be necessary but it will overwinter better if left intact and cleaned up in the spring
- Lavender – Don’t prune late in the seasons. New growth is extremely cold sensitive. Wait until new growth appears in the spring before removing winter die back
- Lavender Cotton (Santolina) – Do not prune after August as it needs time to harden before winter. Wait until new growth appears before pruning
- Mums – Leave the foliage to protect the plants crown from the cold
- Russian Sage – Like lavender, the new growth of Russian sage is sensitive to the cold. Cut back in the spring to about 6-8 inches when you see new growth emerge
- Tickseed (Coreopsis) – Leaving the foliage seems to improve its chance for winter survival
- Guara – Guara is such a short-lived perennial that allowing the flowers to remain and self-seed may be the only way you will see another pop up in the garden
- Removing Annuals – For the same reason as cutting back your perennials, you want to remove your annuals to decrease the chance of harboring insects and diseases through the winter.
- Roses- This depends on what kind you have: i. Knockout Roses – Knockouts should be left alone until spring. People always ask to have them cut them back in the fall. However, it is best to wait until spring. Come spring, they should be cut back to a height two feet below where you would like to see them finish ii. Tea Roses – Tea roses are the most sensitive and may take a little more care than knockouts. 1. It is important to stop fertilizing and pruning in the late summer. This will prevent stimulating tender new growth which would be killed by the first frost 2. Make sure to remove old mulch and debris to prevent harboring insect eggs or disease spores 3. Mulching around the base also helps insulate the roots. Not so much to keep them warm, but to maintain an even temperature since we have freezes and thaws throughout the winter. Apply just before the first hard frost. If you have rodent problems, wait until the ground has frozen. Be sure to remove in the spring before new growth emerges.
Fertilizing– Fertilizing isn’t a fall must, but because we often remove all of our leaves from the beds –and all the wonderful natural fertilizer that they contain – it doesn’t hurt. Taking the time to fertilize in the fall will strengthen your plants’ roots, giving them a strong base on which to thrive next spring.
- What do all the numbers mean? – You need to first understand the formula. There are three numbers on a bag, bottle, or can of fertilizer. It might read 14-14-14. This is the percent of nitrogen, phosphorus and potassium (N-P-K). Nitrogen promotes foliage growth, phosphorus helps root growth, and potassium promotes cell function and absorption of trace elements. That being said, a fertilizer high in nitrogen would not be recommended because you do not want to promote new growth. Choose one with a higher middle number to promote root health.
- Organic vs. Inorganic? The answer to this question often depends on your garden’s needs. i. Organic Organic fertilizers are composed of natural ingredients from plants or animals. They rely on soil organisms such as earthworms to break down organic matter. Because of this process it is a slow release fertilizer. Organic fertilizers improve the overall health of the soil. ii. Inorganic – Inorganic fertilizers can be slow or quick-release. They are good for plants which need a large amount of nutrients for a short amount of time such as bedding annuals. The concentrated form increases the risk of burning the plant if applied incorrectly, and the quick-release of nutrients may result in soil leaching.
Mulching – Mulching in the spring and summer helps control weeds. In the fall it has a different purpose. In areas like ours, where we have freezing and thawing mulching helps protect the plants from heaving. Mulch helps maintain a more even temperature and also raises the freezing line, which encourages earthworms to work closer to the surface of the soil.