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March

GARDEN TIPS FOR MARCH!

by David Hillock

Lawn and Turf

  • Remove excessive thatch from warm-season lawns. Dethatching, if necessary, should precede crabgrass control treatment. (HLA-6604)
  • Broadleaf weeds can easily be controlled in cool-season lawns at this time with post-emergent broadleaf herbicides.
  • Pre-emergent crabgrass control chemicals can still be applied to cool- and warm-season turfgrasses. Heed label cautions when using any weed killers near or in the root zone of desirable plantings.
  • March is the second best time of the year to seed cool-season turfgrass; however, fall is the best time to plant. (HLA-6419)
  • Cool-season lawns such as bluegrass, fescue, and ryegrass may be fertilized now with the first application of the season. Usually, four applications of fertilizer are required per year, in March, May, October, and November. (HLA-6420)
  • Begin mowing cool-season grasses at 1 ½ to 3 ½ inches high. (HLA-6420)

Flowers & Vegetables

  • Cultivate annual flower and vegetable planting beds to destroy winter weeds.
  • Apply mulch to control weeds in beds. Landscape fabric barrier can reduce the amount of mulch but can dry out and prevent water penetration. Thus, organic litter makes the best mulch.
  • Prune roses just before growth starts and begin a regular disease spray program as the foliage appears on susceptible varieties. (HLA-6403 & EPP-7607)
  • Avoid excessive walking and working in the garden when foliage and soils are wet.
  • Start warm-season vegetable transplants indoors.
  • Divide and replant overcrowded, summer and fall blooming perennials. Mow or cut back old liriope and other ornamental grasses before new growth begins.
  • Your cool-season vegetables like broccoli, cabbage, carrot, lettuce, onion, peas, spinach, turnips etc. should be planted by the middle of March.
  • Watch for cutworms that girdle newly planted vegetables during the first few weeks of establishment.  Cabbage looper and cabbageworm insects should be monitored and controlled in the garden (EPP-7313).

Garden Planting Guide for Cool-Season Vegetables

It’s not too late to start some of those cool-season plants for a spring harvest; that is if the weather doesn’t jump right to summer anytime soon!

Below is a chart that will assist you in determining the time and method to get your favorite cool-season vegetables off to a good start. For suggestions on varieties, see our fact sheet HLA-6032 – Vegetable Varieties for the Home Garden in Oklahoma.

Vegetable

Time to Plant*

Days to Harvest

Method of Planting

Asparagus

Fall or Spring

-

Crowns

Beet

March

50-70

Seed

Broccoli

March

80-90

Plants

Cabbage

Feb. 15 to March 10

60-90

Plants

Carrot

Feb. 15 to March 10

70-90

Seed

Cauliflower

Feb. 15 to March 10

70-90

Plants

Chard, Swiss

Feb. 15 to March 10

40-60

Seed

Kohlrabi

Feb. 15 to March 10

50-70

Seed

Lettuce, Head

Feb. 15 to March 10

60-90

Seed or Plant

Lettuce, Leaf

Feb. 15 to March 10

40-70

Seed or Plant

Onion

Feb. 15 to March 10

60-120

Sets

Onion

Feb. 15 to March 10

60-120

Plants

Peas, green

Feb. 15 to March 10

60-90

Seed

Potato, Irish

Feb. 15 to March 10

90-120

Tuber pieces 2-3 oz.

Radish

March 1 to April 15

25-40

Seed

Rhubarb

Fall or Spring

-

Crowns

Spinach

Feb. 15 to March 10

50-70

Seed

Turnip

Feb. 15 to March 10

50-60

Seed


*These dates indicate planting times from southeast to northwest Oklahoma. Specific climate and weather may influence planting dates. For cool-season vegetables, the soil temperature at the depth where the seeds are planted should be at least 40°F.

Trees & Shrubs

  • Prune spring flowering plants, if needed, immediately following their bloom period.
  • Plant evergreen shrubs, balled and burlapped, and bare root trees and shrubs.
  • Anthracnose control on sycamore, maple, and oak should begin at bud swell. (EPP-7634).
  • Diplodia Pine Tip blight control on pines begins at bud swell.
  • Chemical and physical control of galls (swellings) on stems of trees should begin now. EPP‑7168 & EPP-7306)
  • Dormant oil can still be applied to control mites, galls, overwintering aphids, etc. (EPP-7306)
  • The first generation of Nantucket Pine Tip Moth appears at this time. Begin pesticide applications in late March. (EPP-7306)
  • Control Eastern tent caterpillars as soon as the critters appear.

Fruits

  • Continue to plant strawberries, asparagus, and other small fruit crops this month.
  • Start your routine fruit tree spray schedule prior to bud break. (EPP-7319).
  • Remove winter mulch from strawberries in early March (HLA-6214).

Spring Irrigation System Inspection

Joshua Campbell and Justin Quetone Moss

An irrigation system is a tool to keep landscapes healthy and attractive. However, systems that are not kept in proper operating condition can waste water and damage the landscape. An irrigation system should be visually inspected regularly. Early spring is an ideal time to check your system and plan for repairs. Even minor damages or leaks can be big water wasters and can further damage your system if left unattended. It is best to address repair issues as soon as they arise; however, many automatic irrigation schedules are set for the early morning or overnight hours when they are not seen by homeowners. This typically results in many needed repairs going unnoticed. Visually checking your irrigation system each spring will help improve water use efficiency and keep your landscape healthy and attractive.

How to inspect your system – Go to your controller and turn on each irrigation zone one at a time, or set your controller to run through each zone, using the test cycle setting if available. If you choose to run a test cycle of each zone, set a time limit long enough to observe each zone and mark needed repairs. Three minutes is typically enough time for a home irrigation system. Grab a clip board and note pad and walk through the landscape zone by zone while your system is running. Look for the following issues and make notes of needed repairs:

  • Sprinkler heads spraying a sidewalk, driveway or road
  • Geysers from missing or broken sprinkler heads
  • Sprinkler heads leaking at the base or not popping up from the ground
  • Rotors stuck in one position, failing to turn
  • Water misting from the sprinkler due to high pressure
  • Dry areas due to low water pressure or a clogged nozzle 
  • Wet or spongey areas possibly indicating a broken or leaking pipe
  • Grass, shrubs or trees blocking sprinkler spray patterns
  • Electrical issues such as broken wire, valves not turning on, or a controller error code

Many repairs are simple fixes once identified. However, more complicated repairs may require an experienced landscape maintenance professional.

If you don’t have an in-ground irrigation system, but use hoses, or drip irrigation, be sure to check your tubing for leaks. Many leaks occur at the connection to the spigot. If your hose leaks at its connection, replace the rubber hose washer and ensure a tight connection to the spigot using pipe tape and a wrench. Using these tips can help your system to run efficiently, save water, and save money over time.

March Weed Control Tips

Dustin Harris and Justin Quetone Moss

Due to abnormally high temperatures throughout the month of February, herbicide applications to warm-season grasses should be carefully considered for March. Before applying a non-selective herbicide such as glyphosate to control winter weeds, it is necessary to verify that the treatment area has not exited dormancy. Many bermudagrass lawns in Oklahoma are already greening up this spring. If so, the application of glyphosate may cause the death of the desirable turfgrass species. Other postemergent herbicides, even selective herbicides, may largely affect the spring green-up timing by a range of a few days to a few weeks. Therefore, it is especially important to monitor the lawn for indications of spring green-up and follow the labeled recommendations before making any herbicide applications to turf stands.

Furthermore, if the weed population is manageable by physical removal, hand-weeding might still be the most practical method of control. However, if the weed population is beyond your threshold for physical removal, a delayed spring green-up would be desired over the competition presented by a mature weed population. Therefore, a product that is labeled for use in the established turf species may be necessary to maintain optimal turfgrass if the weed infestation is severe enough. A simple spot-treatment application may be more practical for small areas or areas with low weed population densities, but a broadcast application may be best suited if the infestation is widespread. However, those two methods of application often require different dilution rates according to labeled recommendations.

Additionally, if your lawn has not received a preemergent herbicide application this year, now is the time to apply before problematic summer annuals begin to germinate. Crabgrasses, foxtail, and sandburs are among the grassy weed species that should not have germinated yet. These are grassy weeds that are best controlled through the use of preemergent herbicides. So, if you’d rather avoid additional mowing throughout the summer or picking sandburs out of yourself and your clothing, be sure that your lawn has been treated appropriately.

As always, it remains important to read product labels in their entirety before making any herbicide application. Additionally, the accurate identification of the weeds you desire to eradicate will aid in selecting the most effective herbicide or combination of herbicides for control of the species present. For additional resources in weed identification and control, contact your respective county extension agent. Additional information on broadleaf weed control can be found in OSU Fact Sheet HLA-6601: Consumer Broadleaf Weed control for Lawns in Oklahoma.

Growing Transplants Indoors

David Hillock

Many gardeners choose to start their own seeds at home, rather than purchasing transplants, and you can still start summer vegetables and flowers indoors to get a jump on the season. The advantages include savings in cost, and also the availability of a much wider selection of cultivars.

After seeds have germinated, they must be promptly given the best possible growing conditions to ensure stocky vigorous plants for outdoor planting. Cultural requirements must be considered carefully.

Light – Seedlings must receive bright light promptly after germination. Place them in a bright south-facing window if possible. If a large, bright window is not available, place the flats under fluorescent lights. A fixture containing two 40-watt fluorescent tubes is adequate. Place the seedlings about 6 inches from the tubes and keep lights on for 14 to 16 hours each day. As seedlings grow, the lights may need to be raised to prevent leaf burn as seedlings touch the tubes.

Plants need some red and infrared radiation. Since this is not supplied by common fluorescent tubes, additional light from incandescent lamps or windows is necessary. If this cannot be given, use a fluorescent tube specially designed for plant growing. These are available under a variety of trade names.

Temperature – Most annual plants and vegetables prefer nighttime temperatures between 60 and 65 degrees F. Day temperatures may run about 10 degrees higher. If temperatures are warmer than this, leggy plants result. Cool-season vegetable crops and a few flowers already listed prefer night temperatures no higher than 55 degrees F and day temperatures near 65 degrees F. An unused bedroom, basement or sun porch is often a good location.

Moisture – Good humidity is an asset for producing good plants. A humidifier may be used, or shallow pans of gravel filled with water may be placed as close to the growing area as possible. Flats should be kept moist at all times but never soggy. Allow drying between waterings, but don’t allow seedlings to wilt at any time.

Fertilization – Seedlings will need some fertilization for best development. Those in totally artificial mixes need prompt and regular fertilization. Use a soluble house plant fertilizer as sold in garden centers and nurseries. Young, tender seedlings are easily damaged by too much fertilizer. Apply fertilizer at about half the recommended strength a few days after seedlings have germinated. After that, fertilize at two-week intervals with the dilution recommended by the manufacturer. Water and fertilize carefully.

“Damping off” – When seedlings fall over at the ground level, they are being attacked by a fungus disease known as “damping off”. If only a few seedlings are attacked, dig out and discard the infected plants and soil. Drench the entire soil mass with a fungicide if the disease is scattered throughout the flat or pot. This may not provide complete control. High temperature, poor light, or excess moisture stimulate spread of the disease by weakening plants to make them more susceptible to it. Best control is cleanliness and prompt action when the disease appears.

Pruning Roses

David Hillock

The pruning of roses varies according to flowering habit and plant vigor. Most Oklahoma roses should not be pruned before March 15. Pruning tends to cause new growth which is often killed by late spring freezes. However, most modern roses should be pruned annually. Prune to maintain plant shape, remove dead or diseased wood (often dark or blackened canes), and regulate desired flower size. If only a few large flowers are preferred, cut the plants more severely. Too much spring pruning can weaken plants. If a large number of average-sized flowers are preferred, only light or moderate pruning is necessary. Long-handled pruning clippers (loppers) and hand clippers are needed for pruning roses. A sharp, fine-toothed pruning saw is also useful for cutting large dead canes.

Leaves and stems grow from buds. Bud position determines the shape of the plant. Prune for an open-centered plant. Thus, make all cuts just above outward-facing buds. Make the cut slightly above and angling downward away from the bud. Remove branches that grow toward the center of the plant. When two branches cross, the smaller one should be removed. Any growth originating below the union with the understock should be removed from such budded roses as hybrid teas and floribundas. If the average number of leaflets on the stems of such roses is more than five, the cane is probably understock.

Hybrid tea roses usually require relatively severe pruning because of winterkill of the canes. In the spring, remove dead or diseased canes. Then, cut back remaining canes to 6 to 24 inches, depending on plant vigor and desired flowering.

Grandifloras, floribundas, and polyanthas require less pruning. Remove dead or diseased canes and shape the plant.

Ramblers and small flowered climbers that bloom only in the spring should be pruned immediately following bloom. Spring flowering roses and shrubs set flowering buds in late spring and summer. Remove canes that have flowered from the base or crown of the plant. Train or tie up developing new shoots.

Large flowered climbers that bloom only in the spring are also pruned right after flowering. Cut back side shoots that have flowered, and remove the oldest canes. Train up only enough new canes to cover the desired area and remove the rest.

Remove only very weak or dead branches of climbers that bloom all summer. These climbers can be pruned lightly after the first burst of bloom.

Heavy cutting of flowers, particularly with long stems, should be avoided during a plant’s first year of growth. This will allow the plant to become established more readily. Remove all flowers or flower clusters just above the first five leaflet leaves when the petals begin to fall. Even when cutting flowers from established plants, do not remove more foliage than necessary. Let autumn roses produce hips (seed pods) to induce early freeze hardiness.

Winter Damage to Broadleaf Evergreens

David Hillock

This year I have noticed a significant number of broadleaf plants affected by recent weather conditions. Winter burn seems to be the most common, which occurs on such plants as azalea, boxwood, holly, magnolia, euonymus, nandina, and viburnum, but it can affect narrow-leaved evergreens like pines and deciduous species as well. Winter burn is often misdiagnosed as an infectious disease or damage from excessively cold temperatures. Winter burn is caused from desiccation, which is a type of dehydration injury. When roots are in dry or frozen soil, water lost through transpiration cannot be replenished by the roots and dehydration occurs. Water loss through transpiration is normally low during winter months, but it increases when plants are subjected to drying winds or are growing in warm sunny spots.

Symptoms of winter burn include scorching of leaf tips or outer leaf margins, complete browning of needles or browning from the needle tips downward, or death of terminal buds and/or twigs. Broadleaf evergreens affected by winter burn will likely survive and send out new shoots and leaves this spring, depending on the severity of the damage. Where death of tips and/or small twigs has occurred, simply prune back to live, undamaged tissue.

Several means of eliminating or minimizing winter burn may be used. Avoid planting broadleaved evergreens in areas of high wind exposure. Deep water plants during dry periods throughout winter months when temperatures remain above freezing for prolonged periods. Erect physical windbreaks. Burlap “walls” can help cut down wind and subsequent moisture loss to evergreen shrubs and small trees. Antitranspirants of various types are available, but have shown limited success under Oklahoma’s climatic conditions.

2017: Year of the Daffodil

National Garden Bureau

Daffodils, a spring-blooming, self-propagating perennial, originated in Europe, predominantly Spain, Portugal, France and Austria, where they are native to meadows and woody forests.  Some naturalized in Great Britain and from there, narcissus bulbs were introduced to North America by pioneer women who made the long ocean voyage to America to build a new future.  Given limited space for bringing personal goods, they sewed dormant daffodil bulbs into the hems of their skirts to plant at their new homes to remind them of the gardens they left behind.  The remnant ancestors of those bulbs still persist today in older gardens in the eastern half of the US, making them a part of our heritage for over 300 years!

The official botanical genus name for Daffodils is narcissus, which comes from the Greek word ‘Narkissos’ and its base word ‘Narke’, meaning sleep or numbness, attributed to the sedative effect from the alkaloids in its plants. The plant family is Amaryllidaceae, meaning all members are poisonous, which is great for gardeners because that makes them critter proof. Daffodil is actually just a nickname, not a scientific or Latin name.

The Royal Horticultural Society divides narcissus into 13 divisions based on type, size, or number of flowers. To learn more about the 13 divisions go to the National Garden Bureau web site http://ngb.org/year_of/index.cfm?YOID=47.

Unlike many spring flowering bulbs, daffodils are not eaten by mice, voles, squirrels, rabbits or deer because they are poisonous and distasteful, which helps to keep pets and children from ingesting them. Daffodils are great for picking and arranging in cut flower bouquets and they are also perfect for container planting and forcing.

The ideal daffodil planting time depends on where you live. In zones 6-9, wait until October-December.

Bulb sizes are determined by the age of the bulb and also the division of the cultivar. Division 1-4 tend to be larger (14-16cm or 16- 18cm in circumference) than Division 5-7 (12- 14cm or 14-16cm). Of course, miniatures are normally smaller sized bulbs (8-10cm or 10- 12 cm).

Planting Instructions:

Keeping bulb size in mind, daffodil bulbs should be spaced 3x the width of the bulb apart, or 4- 6” on center, depending on the size of the bulb. As for planting depth, daffodils should be planted 3x the height of the bulb deep, or 4-6” to the bottom of the hole, depending on the size of the bulb. Planting in full sun is preferable, but partial shade (at least 1/2 day) is acceptable.

Digging and dividing is normally not necessary if the bulbs are planted in fertile soil, have sufficient water during the spring growing season, and if they get plenty of sunlight for 6 weeks after the blooms are finished. However, if you do want to divide them, do so as soon as the foliage begins to turn yellow. Dig under the whole clump with a spading fork, shake off the loose soil and carefully separate the roots of the large bulbs from one another. If daughter bulbs are attached to the mother bulbs, it’s best to leave them together - they will separate underground when the time is right. The best choice is to replant bulbs immediately after digging, however if storing is necessary, store dry in mesh bags with plenty of air circulation. Removing spent flowers is nice for aesthetic reasons, but because most hybrid daffodils have very little nectar and have heavy, distasteful pollen which is seldom spread by the wind or insects, few are accidently pollinated. Therefore, few produce real seeds which would drain the bulb’s energy needed to produce next year’s bloom...so it’s not really necessary to deadhead daffodils.

Credit: The National Garden Bureau, http://ngb.org/

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