Pat Curran

What to do in the garden in September & October

by cathym on September 11, 2020

Hips on Rosa rugosa

SEPTEMBER 
Ornamentals
Continue to deadhead some perennials and annuals to keep them blooming, others to avoid self-sowing. You may want to leave seedheads for the birds on plants like echinacea. 

Stop deadheading most roses. This will allow them to start transitioning to winter. Rosehips are an added bonus with some kinds of roses.

Keep container plants watered and fertilized.

Evergreens, including conifers, should be planted by mid-September to allow them plenty of time to root. The newly planted broadleaf evergreens will need winter protection from sun and wind. Continue to water all newly planted woody plants. Ten to fifteen gallons of water is needed weekly when rainfall is less than one inch. 

Protect tree trunks from buck rub as soon as possible.

Plan to protect woody plants from browsing by deer, rabbits and rodents. The bark and the buds on the branches are all susceptible.

Bearded irises should have been divided and/or planted last month but if you do so in September, place a stone or brick on top of the rhizome to prevent winter heaving (this tip courtesy of the Southern Tier Iris Society).

Keep water gardens full. Continue to prevent mosquito development. Use mosquito dunks if necessary—these contain a type of natural Bt that kills mosquito larvae.

September is the best time to renovate or install a lawn. Cooler weather and hopefully more moisture allow better germination and growth of the grass seedlings. Mowing the lawn as high as possible results in a healthier lawn with deeper roots more tolerant of drought and denser turf that will prevent germination of some weed seeds. 

Now is a good time to move spring-blooming bulbs if you can locate them. Many will already have roots so don’t let them dry out.

Photograph your garden and make notes of needed changes. I put notes on next year’s calendar so I don’t forget what I wanted to do next April or May.

Now is a good time to plant hardy perennials and woody plants. Keep them watered to encourage rooting.

Narcissus is best planted in September after the soil has cooled a little. Delicate bulbs such as fritillaria and trout lilies should be planted as soon as you get them. Winter aconite tubers and Anemone blanda tubers should be soaked in lukewarm water for several hours before planting. This is very effective for A. blanda, less so for winter aconites, which are best propagated by seed.

Nursery stock goes on sale and may be a good money saver if it has been well cared for. Score the rootball of pot-bound plants with vertical cuts to ensure root growth into the surrounding soil. If rain is insufficient, water weekly. Continue watering until the ground freezes.

Check viburnums for viburnum leaf beetle (VLB) adults, especially if the shrubs were defoliated by the larvae. Consider a pesticide treatment to save the shrubs. Do NOT cut back branches just because the leaves have been eaten or damaged. Scratch the bark with your fingernail, if it’s green underneath, the branch is alive. Snip off and destroy the twigs that contain the VLB eggs. Although the egg-laying sites are most obvious in the fall, one actually has until April to trim the affected twigs.  

It is too late to fertilize woody plants, as doing so may encourage tender late growth that may not harden off in time for winter.

It is also too late to prune woody plants, except for dead or diseased wood. Be especially mindful not to prune spring-blooming shrubs that have already formed next spring’s flower buds, such as forsythia.

Bring in poinsettias and Christmas cacti to get them adapted to indoor conditions. Start exposing them to long nights (short days) for flower buds to set. After checking for insects, bring in houseplants before nights cool off too much outside and heating systems start operating. 

Consider having windowsill herbs for winter use. You may pot up small ones or take cuttings—basil, sage, rosemary (especially susceptible to drying out in my experience) are some of the possibilities. Chives are a hardy perennial; pot them up and bring them inside in late fall.

If you live in a cold site, you may want to dig tender bulbs such as dahlias, tuberous begonias, and cannas before the frost hits. This winter I am planning to keep canna ‘Stuttgart’ growing on a windowsill. Cannas do not need a rest period.  Gladioli seem to be marginally hardy even in my cold site. One has persisted and bloomed for three years outdoors now, and others survived last winter, but may not bloom this year. I may leave them all in the ground and see what happens!

Edibles
You should already have harvested garlic.

Keep up with weeding! If you can’t remove all the weeds right away, at least don’t let them go to seed.

Renew the mulch in your veggie garden or consider planting hardy cover crops to improve the soil.

Pick fall raspberries every day, especially if the weather is wet or humid. If raspberries or other soft fruits look moist or misshapen, check for the maggots of the spotted wing drosophila fruit fly. Destroy all the bad fruit. If a lot of fruit has been set, you can then use row cover to keep the fruit flies out, but this will also prevent further pollination. Also look out for the brown marmorated stink bug. 

Keep harvesting veggies and herbs and continue to water if it is dry.

If you garden in a cold site, start watching for frost after October 1 be prepared.  (The average first frost in zones 5 and 6 is in mid-October.) 

Now is a good time to do a soil test and make pH amendments as needed but wait until spring to apply fertilizer.


OCTOBER
Ornamentals
Continue to water newly planted woodies. You can continue to plant hardy perennials and woody plants such as tall phlox, hostas and lilacs. The shallow-rooted perennials such as Heuchera should have been planted earlier.

This is the best time to move peonies. Normally, they don’t need to be moved or divided unless they are growing in too much shade. It may take a couple of years for them to recover after dividing or moving. Do not plant them too deeply; doing so may cause them not to bloom.

Continue to plant spring-blooming bulbs. Tulips can be planted last. Many spring-blooming bulbs are deer-resistant, such as alliums, winter aconite, snowdrops, snowflake, Siberian squill, glory-of-the-snow, puschkinia, fritillaria, and Anemone blanda. Grape hyacinths send up fall foliage but even when it’s browsed it doesn’t seem to affect their vigor.

Cut off all the peony foliage down to the ground to remove botrytis spores.

Some perennials can be cut back now for the winter, if the foliage has senesced already.  Leave stalks of natives in place in case beneficial insects use them for overwintering.  Also, do not trim back the stalks of certain plants that overwinter better with the protection of the old stalks. This group includes mums, lavender, culinary sage, Kniphofia and butterfly bush.

Late in the month, look for spring bulbs on sale. Consider forcing some: daffodils, crocuses, hyacinths, and smaller bulbs like Siberian squill all force well. Tulips can be forced, too, but they require a longer rooting period and stronger light in the foliage-growing stage or they will be leggy and floppy.

Edibles
Listen to the fall forecasts and be prepared to protect tender plants from an early frost with old sheets, towels, etc., as we frequently get a couple weeks of nice weather afterwards. Otherwise, when frost is predicted, do a quick harvest to get produce indoors.

Mid to late October is the best time to plant garlic. Be sure to rotate garlic; pick a new spot with lots of sun and good drainage. I mulch it with a couple inches of woodchips to give it plenty of time to root but preferably not to sprout.

Remove all the brown asparagus ferns to reduce the number of overwintering asparagus beetles.

Continue weeding, watering and mulching as needed.

— Pat Curran and the Tompkins County Master Gardeners

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Almanac: July – August 2019

by cathym on July 25, 2019

Divide and replant bearded irises.

JULY
Ornamentals
Pinch back chrysanthemums and asters to keep them shorter and bushier. Stake perennials that tend to flop.

Deadhead some perennials and annuals to keep them blooming, others to avoid self-sowing and the plant’s wasting energy on seed production. 

Cut back mounding perennials such as geraniums, pinks, alyssum, creeping phlox, and aubretia when they are finished blooming.

Cut reblooming roses back slightly.

Keep container plants watered and fertilized.

Water newly planted woody plants. Ten to 15 gallons of water is needed weekly when rainfall is less than one inch.

Plan how to protect woodies from deer.

Keep water gardens full.

Deadhead Japanese tree lilacs as much possible to encourage more bloom next year and prevent unwanted seedlings.

Mowing the lawn as high as possible results in a healthier lawn with deeper roots more tolerant of drought and denser turf—this will prevent germination of some weed seeds.

Start some perennials from seed, but plan on overwintering them in a cold frame. 

It’s finally okay to remove narcissus foliage. This is also a good time to move the bulbs, or you can dig them up and let them dry for planting in September.

Move colchicum in early July. If you forced bulbs last winter, remove them from the pots and store them dry and cool for the summer (except for delicate bulbs like snowdrops). Watch out for narcissus bulb fly!

Divide and replant bearded irises. Destroy old or rotten rhizomes or those with iris borers. Do this before Labor Day to allow sufficient time for rerooting.  

Tour private gardens and arboreta. Take your camera and notebook to record ideas.

Mark colors of phlox and daylilies in case you want to propagate and share them. Photograph your garden and make notes of needed changes.

Check viburnums for viburnum leaf beetle (VLB) adults, especially if the shrubs were defoliated by the larvae. Consider a pesticide treatment to save the shrubs. Do NOT cut back branches just because the leaves have been eaten or damaged. Scratch the bark with your fingernail. If it’s green underneath, the branch is alive. Dormant buds under the bark will eventually develop into sprouts and leaves. Snip off and destroy the twigs that contain the VLB eggs. Although the egg-laying sites are most obvious in the fall, one actually has until April to trim the affected twigs.  

This is the last month to fertilize woodies without encouraging tender late growth that may not harden off in time for winter. It’s also the last month to prune woodies—except for dead or diseased wood.

Edibles
Early in July, emove peas and other early veggies and replace with either quick-growing veggies such as snap beans, cucumbers, summer squash, green onions, beets, kohlrabi, and radishes, or else cool-tolerant, slower-growing veggies such as carrots, broccoli, cauliflower, cabbage, collards, kale, peas, head and romaine lettuce, and parsley.

After August 1, only plantings of leaf lettuce, spinach, turnips, and radishes can be expected to produce a crop in a normal year in upstate New York—gardens in zone 6 near the lake have another week or two of growing season. Cover newly planted seeds with rowcover to keep them cooler and moist.

Renew the mulch in your veggie garden.  

Keep up with weeding! If you can’t remove all the weeds right away, at least don’t let them go to seed.

Cover blueberry plants with bird netting before birds discover the fruit. If it’s dry, water the plants well.  Use large buckets, with holes drilled in the bottom for slow deep watering and to measure how much you are applying. Before renewing the mulch, do a pH test. If the pH is higher than 5.5, consider broadcasting sulfur on the ground and watering it in before mulching. Your Extension office can advise you how much sulfur to apply based on pH.

Keep tomato branches inside their cages. Remove spotted or yellow leaves (put them in the trash). This will slow down early blight and septoria leaf blight. A layer of fresh mulch may help to interrupt fungus infection.

If you suspect late blight, take leaf samples or pictures to your local Extension office.

Continue to cut off curly garlic scapes as they appear to encourage larger bulbs. 

Pick raspberries every day, especially if the weather is wet or humid. If raspberries or other soft fruits look moist or misshapen, check for the maggots of the two-spotted drosophila fruit fly. Destroy all the bad fruit. If a lot of fruit has been set, you can then use rowcover to keep the fruit flies out, but this will also prevent further pollination. Also look out for the marmorated stink bug.

Keep your food plants weeded, watered, and mulched. Uneven watering may cause blossom end rot of tomatoes. Blueberry bushes are particularly sensitive to drought

Carefully guide melon and squash vines where you want them to go.

Renew or move the strawberry bed. Moving the plants now allows thorough weed removal and enough time to plant a succession crop (see above).

Keep the asparagus bed weeded. You shouldn’t be harvesting any longer. Watch for asparagus beetles.

Maximize basil harvest and prevent blooming by cutting plants back by one-third rather than just plucking leaves. 

Handpick Japanese beetles, Colorado potato beetles, etc. Look for the eggs on undersides of leaves. Use Bt insecticide on cabbage family plants, but remember Bt will also kill the caterpillars of desirable butterflies. Grow extra parsley, dill, or fennel to have more black swallowtails, and leave common milkweed in rough areas for monarch caterpillars.

If you have a lot of apples or crabapples, thinning the fruit may reduce the tendency to biennial bearing that might result.

AUGUST
Ornamentals

Continue to water newly planted woodies (see July). Plant evergreens by mid-September in order to establish before winter.

In late August, plant corms of either colchicums or the true autumn crocus (Crocus speciosus, etc.) as soon as they are available.

Nursery stock goes on sale and may be a good moneysaver if it has been well cared for. Score the rootball of pot bound plants with vertical cuts to ensure root growth into the surrounding soil. If rain is insufficient, water weekly. Continue watering until the ground freezes.

In late August, preferably before the end of September, move and/or divide some of the hardier perennials, especially the spring-blooming ones.

Order bulbs for fall planting to get the best selection of varieties. Many spring-blooming bulbs are deer-resistant, such as allium, winter aconite, snowdrop, leucojum (snowflake), Siberian squill, glory-of-the-snow, puschkinia, fritillaria, and Anemone blanda. Grape hyacinths send up fall foliage, but even when it’s browsed that doesn’t seem to affect their vigor.

Keep the lawn mowed high, but if a drought drags on, allow it to go dormant (brown). It will revive when rains resume.

Late August and early September is the best time to renovate a lawn or to seed a new one. 

Start protecting tree trunks from “buck rub” damage.

Late in August, bring in poinsettia and Christmas cactus to get them adapted to indoor conditions. Start exposing them to long nights (short days) for flowerbuds to set. After checking for insects, bring in houseplants before nights cool off too much outside and heating systems start operating. 

Edibles
In zone 5, August is the last month to plant early broccoli or cauliflower transplants, leaf lettuce, spinach, and turnip.  Protect them from the scorching sun with rowcover or milk crates.

Harvest garlic when the leaves are yellowing. Next you can weed the area and plant a late crop. Rotate garlic, so pick a new spot with lots of sun and good drainage. Sheet compost the new spot now, until planting time in mid-October.

Continue weeding, watering, and mulching as needed. Try not to get leaves wet to prevent spreading disease. Watch closely for tomato/potato late blight.

Keep harvesting beans, basil, okra, cukes, summer squash, eggplant, etc., for plants to keep producing. It’s okay to leave some peppers on the plant to ripen and turn color.

—Pat Curran and the Tompkins County Master Gardeners

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Almanac: May-June 2108

by janem on May 5, 2018

What To Do in the Garden in May & June

Basil seedlings

May Edibles:
It’s your last chance to start some slow-growing seedlings early in the month, such as tomatoes and parsley. Soak parsley seeds in lukewarm water for a few hours first. Consider getting a heated germination mat to accelerate germination. After germination, take the plants off the mat and hang fluorescent lights about four inches above them. It’s OK for seedlings to have the lights on 24 hours a day—it will accelerate growth.

Around May 10is when I start heat-loving, long-season plants such as winter squash, melons, and okra. Cucumbers and summer squash can also be started then, or you can wait until later in May or June, and seed them directly outdoors, as they are faster growing.

Early in May, there is still time to direct seed some of the cool-tolerant veggies, such as spinach, lettuce, and radishes, that are quick to harvest. It’s probably too late to plant peas, because they won’t produce before the real heat arrives.

Late in the month (or early in June) should be safe to plant your frost-sensitive, heat-loving seedlings outside, especially if you applied black plastic or IRT (infrared transmitting) mulch to warm up the soil in the veggie garden. Use rowcover to keep the plants warmer and prevent early insect attack. For real heat lovers like melons, you can leave the rowcover on for a few weeks, but be sure to remove it when they start blooming.

Now is a good time to fertilize your blueberries with the acid fertilizer ammonium sulfate (notaluminum sulfate), and/or apply elemental sulfur to keep the pH acidic enough.

May Ornamentals:
The average last frost occurs in mid-May in much of Upstate NY, but frosts in late May are quite common in some areas. Be prepared to cover sensitive perennials such as Japanese painted fern, kirengeshoma, true lilies, and even hostas, if a hard frost is predicted. I keep old blankets and sheets for this purpose (do not use plastic).

May and June are the best times to prune those woody plants that are considered “bleeders.” Maples, birch, yellowwood, magnolia, linden, willow, and nut trees are just a few trees that are best pruned in this time frame, after the sap is finished running. Peach trees are also best pruned when in bloom or just afterwards (see the Cornell Guide to Growing Fruit at Homefor details).

The first part of May is still a good time to divide hardy perennials such as daylilies, hosta, and phlox. It’s also when fall bloomers like asters and mums can be divided. Be sure the roots are moist first and be prepared to replant (or pot them up) immediately. After transplanting I use milk crates or buckets to keep the sun off for a couple of days if the weather turns hot and sunny. Now is a good time to pot up (or move) seedlings if you’ve allowed your perennials to self-sow. If you have double-flowered peonies, you should install peony cages early in the month to support the heavy blooms.

Keep applying deer repellent on the succulent new growth as needed.

Prune early-spring–flowering shrubs like forsythia right after they bloom.

Check your ash trees for emerald ash borer and decide if treatment or removal is warranted. Young, healthy trees respond to treatment better than old, declining trees. If you have considerable land, consider leaving some ash trees alone, in case they prove to be resistant.

Either April or May is a good time to use your germination heat mat for getting heat-loving tropical “bulbs” such as caladiums started. Use shallow pots until they sprout. Depending on your microclimate, you may need to pot them up again before they can be safely planted outside. Other tender bulbs or tubers, such as dahlias and cannas, can also be potted up early, but should grow at normal indoor room temperature.

Keep your lawn mower set to three inches or higher, be sure the blade is sharp, and mow frequently as needed. Wait until early fall to fertilize, will encourage root growth rather than top growth.

June Edibles:
Keep up with the weeding! Don’t let the weeds go to seed. After the soil has warmed up sufficiently for peppers and tomatoes, go ahead and put down mulch. Stake or cage your tomatoes before it’s too late. Plant Brussels sprouts transplants. There is still time to sow cucumbers and summer squash. Plant carrots in late June to avoid the carrot maggot, which usually has only one generation a year.

Now it’s time to harvest peas and strawberries! Juneberries (a.k.a. amelanchier or shadblow) will be ripe in May or June also. Finish harvesting rhubarb and asparagus by mid-month.

After fruit trees drop their excess, thin the remaining fruit as needed to get bigger, better fruit (see the Cornell guide cited above).

Install a rain gauge or consider getting an electronic weather station that delivers data such as temperatures, wind speed, and rainfall inches to a display inside the house.

June Ornamentals:
Keep weeding!

Pinch or cut back perennials (before the end of the month) that bloom in late summer or fall, in order to make them shorter and bushier—asters, mums, boltonia, etc. See The Well-Tended Perennial Gardenby Tracy Di Sabato-Aust for details.

Deadhead peonies, bearded irises, and rhododendrons, among others. Look for iris flower fly maggots, especially in Siberian iris, but also in bearded iris.

Dig up spring bulbs that need dividing (leave daffodils to the last to allow the foliage more time to feed the bulbs).

Mid-June is the usual time to take softwood cuttings from deciduous shrubs.

Early in June, it should be safe to move some houseplants outside for the summer. Avoid sunburned leaves by siting them in some shade.

Go on garden tours—they are great fun and there are lots of ideas to borrow from fellow gardeners!

—Pat Curran and the Tompkins County Master Gardeners

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