- Apply mulch over the crowns and roots of some of the less hardy perennials during the coldest part of winter. This will help prevent cold damage. Pine straw, clean hay, dry leaves, and shredded hardwood bark all work well for this purpose.
- Cool-season weeds will be active growth any time a stretch of mild weather occurs. Keep buds mulched 3 to 4 inches deep and promptly pull up any weeds as they appear.
- Cut back and remove old, dead upper portions of dormant perennials. This will keep the garden looking more attractive. Chop up the material and put it in your compost pile. Some perennials don’t go dormant until the first freeze hits.
- Work on getting beds ready and in shape for planting. Eliminate any weeds in existing beds and remove turf from new beds.Amend the soil, add 4 to 6 inches of organic matter (preferably compost), and blend with the soil 4 to 6 inches deep.
- Beds may be prepared several weeks prior to planting. Newly prepared beds may be heavily mulched until you are ready to plant them.
- If you need to dig up and move perennials, get started now. This activity needs to be finished by late March.
- Watch for new growth on dormant perennials, and be careful. They are easily damaged by hoeing or digging!
- Remove old, dead growth on perennials as soon as possible if you haven’t already done so.
- Now is the time to start visiting local nurseries to get an idea of what’s available in your area!
- Watch the weather carefully. March is an unsettled month and periods of warm temperatures can be followed by a sudden freeze. Tender new growth is more susceptible to sudden freezes. Mulch, fabric sheets, or cloth may be placed over perennials you think might be vulnerable. promptly remove coverings when freezing temperatures have ended.
- Warmer temperatures and active growth make watering increasing important if regular rainfall does not occur. Apply slowly over time with a sprinkler or soaker hose to ensure a deep, thorough watering. It is far better for the health of the perennials to water them thoroughly as needed than to water lightly and frequently.
- Newly planted perennial beds will need special attention. Until new perennials have a chance to grow a strong root system into the surrounding oil, they are vulnerable to drying out. Water new planting to maintain moist but now wet soil conditions.
- Established perennials should be fertilized this month. This is most efficiently and economically done using a granular fertilizer applied evenly throughout the bed. <<<<<HCWG recommends>>>> After the fertilizer has been applied, water the bed by hand to wash any fertilizer granules off the foliage and down to the soil. Some gardeners pull out the mulch, fertilize, water and replace the mulch to allow the fertilizer granules to reach the oil more efficiently. This is usually not necessary, however, because fertilizer will eventually reach the soil without the trouble of moving the mulch.
- Control aphids, caterpillars, and any other insect pests with approved aids if needed.
- Nurseries are full of plants! Pay careful attention to spacing when planting perennials. If you are accustomed to planting annuals, you may be tempted to plant the perennials too close. Most perennials grow considerably larger than the small plants you set out. Remember as well that these plants will grow in that location for several years, getting larger every year. The full look you see in photographs of perennials borders happens after the perennials have been growing form some time – don’t expect your bed to look like that a couple of months after planting. It will take most perennials more than one season to reach full size.
- Some plants are in full bloom. Deadhead regularly to keep plants attractive and, in some cases, encourage more flowers. Some perennials will generally send up a few more blooms if the faded flower cluster at teh shoot tip is pinched off.
- As perennials grow, make sure your layer of mulch is at least 3 inches thick. Add more mulch to beds if necessary. A proper layer of mulch will keep soil cooler as the weather heats up, converse soil moisture, and prevent weeds, as well as make perennial plantings look more attractive.
- Deep watering is especially important this time of year if sufficient rain does not fall. If will encourage your perennials to develop a deep root system that will make them stronger and more drought resistant later in the summer. Always water deeply and thoroughly when irrigating perennials, and only as needed. Do not water lightly, frequently, or on a preset schedule.
- Fertilize perennial plantings if you have not done so. Finish up this month.
- Pest problems will likely become more numerous from now on. Insects: Watch out for caterpillars, and beetles, which chew holes in the leaves, and aphids. Look for a white, powdery coating on the leaves of perennials in your garden. Powdery mildew is a common disease that may attack your plants. <<<<HCWG recommends>>>>>
- If you’re just getting around to planting a perennial garden with transplants, you’re late. If you are willing to put in extra effort to get them established in the heat, however, you should be successful. If you just want to add a few more perennials to an existing bed, choose transplants in larger containers for best results. Perennials in small pots are often rootbound and stunted this late in the planting season.
- Soaker hoses aer an effective way to water perennial beds without getting water on the flowers and foliage. Flowers are sometimes damaged by water spraying on them, and foliage that stays dry is less likely to develop disease problems. Snake the soaker hose through the bed to cover the entire area. Remember, always water deeply and thoroughly when irrigating. Do not water frequently, lightly, or on preset schedules. Water does not move a great distance from the hose, so it is important to make sure all the plants in the bed are receiving water. Mulch may be placed over the soaker hose so no one even knows it’s there. To determine how long to leave it on in order to thoroughly water the bed:
- 1. Turn on the soaker hose and check the time.
- 2. After 30 minutes, turn off the hose and go check the bed. Dig in several places with a trowel to determine how deep the water has penetrated and how far out from the hose. Note any dry areas and readjust the hose if necessary. Soaker hoses not only place water into a plants’s root zoen but also save up toe 50 percent on water usage.
- 3. If sufficient water was applied to soak most of the bed 4 to 6 inches down, you know to leave in on 30 minutes. If not, leave the hose on for another 20 to 30 minutes and check the soil Continue to water and check until the bed is properly watered. Note the time it takes. It’s a bit of a bother, but you only have to do it once.
- Most of your fertilizer applications should be finished by now. If for some reason you haven’t fertilized yet – better late than never. Apply a premium quality, long lasting, slow-release granular fertilizer appropriate for your area. <<<HCWG recommends>>>>
- Most activity in the perennial garden now centers on care and maintenance.
- Perennials transplants growing in containers can be planted now, but it’s harder for them to establish when it is hot. Container-grown perennials may be pot-bound this time of the year. Prior to planting separate roots as best you can to allow them to uptake more nutrients & water as well as to borough into the surrounding soil.
- These next three or four months are the most stressful of the year. The weather is bound to be too wet or too dry at various times. Water deeply and thoroughly as needed. Do not water frequently, lightly, or on preset schedules.
- Another application of fertilizer may be made to beds last fertilized in march or April. Evaluate the plants before you do. If they are growing vigorously and have a rich green color and plenty of flowers, fertilization is optional.
- Pest problems abound this time of year. Catepillars are common and damage plants by chewing holes in leaves.
- The whitefly can be a difficult insect to control, especially in mid to late summer if populations get way out of hand. The adults are small. The larvae appear as small disks under the leaves.
- Aphids cluster on new growth and flower buds sucking the sap from the plant. They are relatively easy to kill but may return, requiring additional application of pest-control aids/products.
- Various sucking insects such as leaf hoppers, thrips, and plant bugs cuase small white flecks to appear on the foliage of many perennials. The damage is generally little more than cosmetic, but it can weaken the plant if extensive.
- Spider mites can be devastating, especially during hot, dry weather.
- Visit your local nursery for assistance and suggestions on various methods and aids to prevent or control pest problems including insects, diseases, and weeds.
- Plan on getting most of your gardening work done during the cooler mornings & evening hours. The heat is brutal this time of year.
- It’s not an ideal time to plant into the yard, but if you would like to – plant with as little root disturbance as possible and keep well watered until they get established. Applying a root simulator at planting time using label directions should aid in root establishment.
- Cruise your garden and take note of what you see. Make plants and decide on which plants might need to be transplanted or replaced this fall. You can see the beginnings of pest and disease attacks, the onset of weed problems, the need for water, the overgrown plants that might need to be pruned back or supported, and the faded flowers which need to be removed.
- Proper watering is essential this time of year. Hand watering your beds is not sufficient. We usually apply water too fast and over too short a period of time for it to deeply penetrate the soil. Use soaker hoses, drip irrigation or sprinklers and leave them on long enough for the water to moisten the soil about 4-6″ down. Morning is the preferred time to water so plants are well supplied with water going into the hottest time of the day. Evening water is discouraged as plants go into the night wet which encourages fungal diseases.
- Only perennials that are actively growing should be fertilized. Those that are done blooming should be left alone.
- Buy and plant salvias now if you can find plants in the nurseries and have some open spots in the garden. Most salvias put on a wonderful color display in the fall and into early December.
- Salvias are heavy feeders – a light fertilizer application will encourage vigorous growth and abundant October flowers.
- Prune back overgrown perennials. Continue to cut back and remove dead flower stalks and unattractive growth. Look for vigorous new growth at the base of many perennials, and when you see it, cut back the plant hard.
- Most summer-blooming perennials are finished or are finishing up their floral display. Cut back the flower stalks and old faded flowers to keep the plants looking good.
- Mulches may have decayed or thinned out over the summer. Replenish mulch layers with fresh material to maintain at least a 3″ thickness.
- October tends to be one of our drier months. Cooler weather relieves the stress on perennials to some degree, but watering is still needed if it does not rain.
- Look for garden mums! Buy plants that have few open flowers and mostly buds. The plant will be attractive longer. Plant in a sunny or partially sunny location and water regularly.
- Cool to cold weather and regular rainfall generally allow us to ease up this chose.
- Fertilizer is not needed at this time of year.
- Look for winter annuals – such as pansies, cabbages, or cyclamen to plant in your garden for winter color.
- Cut back fall-blooming perennials that have finished blooming. Cut them back and mulch them to 3-4″ deep over the roots and base of the plant.
Material cited from: Gill, Dan and Dale Groom Month by Month Gardening in Texas. Nashville: Cool Springs Press, 2006.