September marks the start of getting the garden – and the gardener – ready for a long winters rest. To this end, consider how best to overwinter and to make room for your favorite non-hardy plants indoors, as well as considerations for your outdoor hardy plants and any new plantings. Fortunately, we still have several months remaining for plants to grow, so there is no rush! Continue to take good notes and pictures on how you weaved together your perennials and annuals this year, since after the first frost these pictures will be all that remains of this year’s favorite combinations!

Things to do:

• Continue to keep your lawn mower blades set high for cutting your lawn. Rain has been ample, although rather sporadic. The temperature look to be average or cooler for the start of the month, which will minimize the stress on the turf.
• September is a great time for the reseeding of bare spots, or for the installation of sod. The upcoming cooler temperatures, heavy dews and typically consistent autumn rainfalls combined with warm soil temperatures promotes good root growth and turf establishment.
• September is a good time to fertilize your lawn. If you wish to fertilize once a year, September is an ideal time as it aids in developing a good root system throughout the winter for next summer’s heat.
• September is a good time to aerate those portions of the lawn that receive excessive foot traffic or have otherwise developed compacted soils.
• If you have yet to start, take cuttings of your favorite annuals that you wish to overwinter. It will be ready to be potted-up in 4-6 weeks. It is far easier to over-winter a small plant that should be free of most insect and disease than lifting a large plant from the ground or outdoor container and bringing it inside.



• Harvest and clean the seed from those annuals and vegetables that come true from seed. Allow them to dry and store them in small paper pouches that are properly labeled and place them in the refrigerator (not the freezer) until next spring.
• Remove those annuals that look excessively tired or leggy and keep removing annual weeds such as crabgrass and stilt grass. Annual weed seed will continue to germinate and appear as long as the temperatures are warm. Remember, on average a seed lasts for seven years and one plant going to seed equates to seven years of additional work!
• Send in your bulb orders! October is a great month for planting bulbs. For Colchicum (Pictured at right), get in your orders in early September or look for them in your favorite garden center. They bloom in late September into early October with typically pink or white flowers and they are deer resistant!
• As a reminder, don’t order just 6-12 bulbs if you are looking to make an impact. For minor bulbs (bulbs that measure close to ½” in diameter), you typically need 50-100 bulbs to begin to make an impact and obviously, the more the better. These bulbs include Snowdrops (Galanthus), Squills (Scilla) Grape Hyacinths (Muscari) and pictured below, Glory of the Snow (Chionodoxa) species. For major bulbs, such as Daffodil (Narcissus), Tulip (Tulipa) and Flowering Onions (Allium) species, 25 to 50 bulbs will make an impact on the Garden.



• For both major and minor bulbs, I like to cluster several bulbs in a hole to create a more mature appearance. For minor bulbs, clusters of 3-8 work well while for major bulbs, clusters of 3-4 give a more mature appearance from the start. These are all things to keep in mind as you put together your bulb order!
• Inspect and evaluate your ornamental small trees, shade trees and shrubs. Even though it has been a relatively moist summer, those plants that are stressed from age or disease will let you know through early leaf wilt or drop. Oaks that have Bacterial Leaf Scorch will have leaves that suddenly turn brown in mid to late August. There are treatments for this disease, but once most of the foliage has turned brown the tree will ultimately need to be removed. It typically attacks older, less vigorous trees and young oaks should still be planted, since the trees feed over 500 native insects!
• September is an ideal time to add woody and herbaceous plants to the garden. The soil is warm and although it is often a relatively dry month, the cooler days and moister weather ahead will allow the plants to establish an adequate root system before next summer’s heat and potential drought. Woody plants that are not fall transplant hazards can be dug and transplanted, and those that are fall hazards can be planted if they were dug this past spring or grown in containers. If rainfall is scarce, water new plantings every 3-4 days through the end of October.
• For the vegetable garden, continue to remove plants that are no longer producing. The wet weather of July and early August raised havoc with tomatoes as the fruit is subject to splitting and cucumbers faded from Powdery Mildew. As mentioned last month, Dr. Bob Mellert mentioned that the days to maturity on seed packets applies for springtime seeding. Come autumn, the number should be multiplied by 1.5 to account for the slower growth time due to the shortening days as compared to the lengthening days of spring. Plant leafy crops that appreciate the cooler nighttime temperatures, such as Arugula, Spinach, Bok Choi, Kale and Lettuce. The full list is below:
Root Crops
Beets (45-64 day)
Carrots (65-80 day)
Fennel, Bulbing (72)
Scallions (60 days)
Kohlrabi (45-60 days)
Radishes (21-48 days)

Leaf Crops
Lettuce (45-55 days)
Mache (like lettuce) (40+)
Mesclun Mixes (30-40 days)
Bok Choy (45 days)
Salad Greens (28-42 days)
Spinach (45 days)
Chard (28-42 days)

Other
Broccoli (55-80)

• If you are planting in containers, consider the leafy crops like Spinach and Bok Choi. They will provide well into the beginning of winter.



• Consider the installation of low tunnels, as seen at right, which are metal hoops covered with a fabric called Agribon. The fabric keeps heavy frosts off a row of cool season vegetables. It enables the gardener to harvest well into December, and for certain crops, into spring! September is a good month to pick-up the materials needed to construct the low tunnels.
• September is an opportune time to plant garlic too! ‘Music’ is an old fashioned favorite and a good performer, but try some of the many other selections that are on the market too! Plant in a location that will be in full sun through next August, which is the harvest period.
• If you live with large deer populations, put wire cages around recently planted trees to avoid the bark being rubbed and damaged by bucks. One of their favorite targets are Magnolias, so make certain that they are properly protected. Damage to bark is far more harmful than the nibbling of a few leaves and I have lost many a tree before we start installing cages.

Bruce Crawford
Program Leader, Home and Public Horticulture (NJAES)

To me, August is the month that epitomizes summer. The days remain long, with the daytime chant of the cicadas with the evening chorus of the crickets. Rainfall in July varied by where you live, but the high temperatures coupled with the generally lower rainfall is showing stress on some plants. August typically has many humid days, but the temperatures are usually in the 80’s, which is good for both the plants and the gardener! Remember to get outside during the cool of the morning or evening, use sunscreen and continue to take good notes of your endeavors.

Things to do:

• Continue to cut the lawn as growth and rainfall permit. Maintain a higher cutting height of 3”+ to reduce the stress on the turf.
• The third and fourth weeks of August are the ideal time for reseeding or seeding new turf areas. The evening dew becomes heavier and helps to ensure proper growth and the warm soils allow proper root development before winter. Supplemental irrigation will be necessary if rainfall is light.
• Make certain plantings from this spring as well as trees planted last year continue to receive weekly irrigation during periods without rainfall. Remember, for a newly installed tree, every inch of caliper size (the diameter of the trunk 6” above the soil) will equate to 1 year of additional care and watering. Hence, a tree with a 3” caliper will require 3 years of additional care.



• Many annuals in containers may begin to look tired. For some, a light pruning with a weekly fertilizing and daily watering will breathe in new life. For others, it is simply time for replacement. For autumn, consider Salvia leucantha (Mexican Bush Sage, pictured at right) and Leonotis leonurus (Lion’s Ear) as alternative options to the garden ‘Mum’.
• Although frost is still 2 months away, at months end you may wish to start taking cuttings of some annuals for rooting, potting and over-wintering for next year’s garden. If your rooting efforts fail, there is still plenty of time to get new cuttings.
• Gather and save seeds of various non-hybrid annuals for seeding next spring.
• The lack of rainfall in some areas has caused some tomatoes to exhibit Blossom End Rot, whereby the base of the tomato turns brown. It is due to a lack of calcium caused by fluctuations in soil moisture. It can be prevented by mulching the plants and giving the soil a deep soaking. The mulch will help prevent fluctuations in soil moisture.
• Bush beans, peas or other crops that have finished producing should be removed, the soil top-dressed with an inch or so of compost, and the area replanted with a crop that will mature within 70 days or by October 15, the average date for frost in NJ. A friend and fellow gardener of mine, Bob Mellert mentioned that the days to maturity on seed packets should be multiplied by 1.5 to account for the slower growth time due to the shortening days as compared to spring. Suggestions for a 2nd crops include:
 
Root Crops
Beets
Carrots
Fennel (bulbing)
Scallions
Kohlrabi
Leeks
Radishes
Leaf Crops
Lettuce
Mache (like lettuce)
Mesclun Mixes
Pak Choi
Salad Greens
Spinach
Chard
Kale
Cabbage
Other
Broccoli Raab
Broccoli
Peas
 
• Arugula, Spinach, and Lettuce are best seeded out near the end of August when the evening temperatures consistently drop into the 60’s and upper 50’s. These crops will endure the early frosts and the spinach actually becomes sweeter as the temperatures become cooler!
• The length of harvest time for the crops listed above can be extended by erecting low tunnels in October to mitigate any of the earlier frosts. Low tunnels consist of hoops placed about 5’ apart and covered with a fabric like agribon that allows air to pass but protects the plants from early frosts. You may wish to look into making or buying the hoops and the row cover fabric now, so you will not be rushed come October.



• Squash plants may be wilting from squash borer. If so, discard the plant (best placed in garbage to remove the borer and any eggs) and plant one of the crops mentioned above.
• August is the time to get your orders in for planting Garlic this fall!
• Resist the urge to vigorously prune shrubs and trees. Heavy pruning during August and September will result in a vigorous production of new shoots that will not become ‘hardened off’ by the first frost, resulting in not only their death, but potentially the death of the plant! Removal of broken branches or light pruning/shaping is still healthy for the plant.
• Many tree limbs will gradually hang down lower following the flush of new growth. If you did not do this pruning back in July, early August is still a good time. Removing the lowest tier of branches on a shade or small tree during August often makes the Garden look more open and able to ‘breath’ again. It also allows more light to reach the plants or turf grass beneath the tree.
• Late August is an ideal time to plant new perennials, shrubs and evergreens in the garden, as the soil is warm and root growth is rapid!
• Try to keep up with the weeding, especially as the summer bloomers are starting to set seed. Remember, if the plant goes to seed, the average life span of a seed is 7 years and that equates to another 7 years of stooping over to weed!
• Continue to deadhead most perennials, roses and annuals to promote new flowers. For some, such as Echinacea, Silphium and Rudbeckia, you may wish to leave the seed heads, since they are an excellent food source for Goldfinches.
• Cut back the predominantly brown Bearded Iris foliage and inspect for borer damage in the rhizome. If the clump is large and root bound, lift and split the rhizome mass apart such that one fan of foliage has an accompanying 3-4” section of the rhizome or horizontal stem. Set the pieces out in the sun for a few days, allowing the wounds to callous slightly and replant, such that the top half of the rhizome remains exposed and uncovered by soil. August is also the month to separate old Peony clumps. Most Peonies can last 20-30 years before requiring division, so if your plant is still providing ample bloom, no division is necessary! Be careful to leave the growth buds of the Peonies at or near the surface to ensure blossom production. If the buds are planted too deep, the plants will fail to bloom. The peony foliage will wilt following division, but the plant will be perfectly fine come spring.
• Bulb orders should be placed for September or October delivery. If you are interested in any of the autumn blooming Cyclamen, Crocus or Colchicum that are pictured below, early August is the time to place your order for a September delivery!

Bruce Crawford
Program Leader in Home and Public Horticulture, NJAES

Finally, the hazy, lazy days of summer have arrived – something many of us longed for during the long cold and damp spring! The temperatures are warm, the sun is high in the sky and the rain has unfortunately been scarce! The heat and humidity have certainly returned too, so try to garden during the cooler temperatures of the early mornings and evenings. Keep records on daily temperatures and rainfall, since summers’ heat and warm nighttime temperatures impact a plant as much as winters’ cold. If you live close to New Brunswick, you can also look at ‘Rutgers Weather’, which has a summary of the weather conditions in Rutgers Gardens over decades. Also, remember to wear a big hat, apply the sunscreen and to drink plenty of water while you garden!

Things to do:

• Weed and fertilize your containers. Water as needed, which is usually once per day. The plants are now beginning to approach their mature size and it is important to keep them well fed and hydrated. If you used slow release fertilizer pellets in your containers, you may wish to consider a reapplication near months end. Most fertilizer pellets only last 2 or 3 months and the rate of release increases as the temperatures soar above 85°F. For heavy feeders, like Brugmansia (picture #1) you should supplement slow release feed with liquid fertilizer – the slow release granules do not release the nutrients at a sufficient rate to support blooming.
• Some annuals, such as Coleus, Plectranthus and Persian Shield (Strobilanthes) would benefit from an occasional pinching of the tip, allowing lower buds to break dormancy and grow (picture #2). This allows the plants to become denser and prevents them from getting straggly or becoming excessively large and ‘eating’ the neighboring plants.
• Hanging baskets should receive a serious cutback in order to renew the plants for a late July through September display.
• Irrigate perennial and annual gardens for long periods ensuring a deep penetration of water into the soil should rainfall be light during that week.
• Reapply mulch to retain moisture should it have become thin or disturbed through replanting of annuals or perennials or from weeding.
• For turf grass, raise the cutting height to 3” during these hotter and drier months to reduce plant stress. If you irrigate, do so for extended periods during the early morning to encourage deeper root growth. Try not to water in the evening, since that will promote various fungal problems. Avoid fertilizing turf during July and early August as that will necessitate more irrigation.
• For Roses, deadhead, give them a light feeding and remove any leaves from the plant or on the ground that have blackspot, as this will help to reduce future outbreaks.
• Any Japanese Beetles on roses or other plants can be destroyed by flicking them into soapy water.
• Some perennials can be lightly trimmed such as the early blooming Salvias (Salvia nemorosa) or more heavily cut back such as Catnip (Nepeta faassenii) and Ribbon Canary Grass (Phalaris arundinacea var. picta) to initiate prolonged blooming or attractive foliage into the fall. Make certain you provide adequate irrigation if you cut the plants back hard. I leave the dried flowers of Yarrow (Achillea) and Astilbe on the plant, as they look attractive in the fall and winter. Early July is the latest time to pinch back unruly Asters and Chrysanthemums, since pinching any later will push bloom time too late into the fall.
• Weed! With the rain and heat, there is an endless growth of weeds this year. It is best to get them young before they become too noticeable and the root systems become too established. Worse yet, try not to let them seed, as the average lifespan of a seed is 7 years which equates to 7 more years of weeding!
• Peas, radishes, lettuce, spinach and other cool season crops need to be composted and replaced by beans, beets or any 80 day to maturity crop. Thin carrots to roughly 1” apart and beets to 2” to allow room for proper root growth.
• At this point summer squash and cucumbers are beginning to come of size; harvest them small (4-6”) and frequently to ensure continued yields and tenderness. If you planted potatoes, they can also be harvested starting in mid-July. A second crop of cucumbers can be planted now to replace those planted earlier that will begin to loose vigor come late August and September.
• Check parsley for Black Swallowtail Butterfly eggs or caterpillars.
• If your Zucchini Squash gets the borer early in the season and collapse, and you still wish to grow squash in that location for this year, consider planting some of the Scallop Squash, often called Patty Pan Squash for an autumn harvest. They mature in about 50-54 days from seed and come in solid White, Golden, and a combination of White and Green Striped. Not only are they delicious, they will add color to the Thanksgiving Table as well!
• When watering tomatoes, make certain that the fruit remains dry in order to reduce the occurrence of blossom end rot. Keep the tomatoes staked (as seen in picture #1 below). By positioning poles along a row of tomatoes and holding the tomatoes upright between two strings, the fruits can be kept off the ground, air can circulate through the plant (reducing disease risks) and ripening fruit is better seen. A close-up of how the plants are supported is pictured below (as seen in picture #2 below. Contact with the ground can also promote blossom end rot and other decay problems.


• Maintain even moisture in the soil around tomatoes to reduce the risk of the tomatoes splitting. This is particularly true of Heirloom tomatoes and using a straw mulch will help maintain consistent moisture.
• Yellowing of the lowest leaves on the stems of tomatoes is an indication of Early Blight. It is best to remove these lower leaves, such that there is no contact with the soil and reducing the threat in the future. Also, wash your hands after removing the leaves before touching other plants to reduce the chance of spreading the disease.
• Provide a light pruning and training of rampant growing Wisteria stems, stray stems of Clematis, and other vines. A heavy pruning will invigorate excessive vegetative growth and less flowering buds.
• Prune water sprouts and suckers on small trees and large shrubs before they become too large and begin to deform the plant. With young ornamental and shade trees, you may wish to prune off the lowest hanging branches, as they will continue to droop lower, shading out any plantings beneath and blocking important views of the garden. Remember, to cut branches back to – but not into – the branch collar at the base of the branch.