Autumn has officially begun and Jack Frost isn’t far away. Many gardens are already showing signs of leaf loss on squash, cukes, peppers, tomatoes, and basil.  These are among the most susceptible plants.  Good News, there are a few easy precautions we can take to protect our favorite plants and extend the gardening season to get a little more out of our summer long efforts.  It’s also the best time to begin improving the soil for next year’s garden so let’s look at how a soil test and composting will be a big help.

Gardeners know well the sad appearance of plants after a frost turns them into leaves drooping lifelessly on once vigorously growing plants.  Heat loving plants are usually the first to go.  Potatoes and onions know that cold is coming so have stopped growing and are pulling nutrients out of their leaves and putting them down into storage.  Trees have begun doing the same so we see the foliage color changes.  We’ll harvest those nutrient rich crops soon.  Others, in the Brassica & Mustard families, almost seem invigorated by the early chills and continue growing bigger and sweeter. This includes cabbage, broccoli, cauliflower, and kales.  Root crops like beets, turnips, parsnips, and carrots are well protected underground and can continue to grow a bit more.  We can’t change the inevitable change of season but there are a few things we can do to extend our garden productivity and enjoyment. 

Crops that have been frost damaged will not recover and should be harvested before more damage can happen.  That means bringing in all frosted winter squashes (butternut, acorn, zucchini, etc.) to fully “cure” (dry) before storage.  Harvest squashes by cutting with an inch or two of the stem attached to reduce rot from entering.  Lay them out in a well-ventilated space of a garage or garden shed to thoroughly dry the skins so they can be stored for the winter months.  Butternut especially needs time to cure and to sweeten the flesh so they will be in their prime for eating by Thanksgiving and afterwards.  Longer storage can be improved by wiping the dried skins off with vinegar or a 10% solution of bleach to eliminate most surface fungi that can cause rot.

Tomatoes and peppers might still be able to ripen existing fruits (yes, they are fruits) once a cold spell has passed.  I recommend harvesting all ripe tomatoes and full-sized peppers now, before the first frost, to let them finish ripening indoors, if necessary.  Green tomatoes can also be ripened indoors.  Put them in a brown paper bag with a ripe apple or banana and check them every day.

Cover plants with row cover (Agribon), bed sheets, or bath towels when frost is forecast.  Blue tarps and black plastic might work but be sure to remove them before the sun shines to avoid overheating.  Cover flowers that you want to save such as dahlias, zinnias, marigolds, impatiens, petunias or move them inside or under a roof.  All of your greens, including kale, spinach, arugula, and most lettuces will be fine without any special protection.

Another simple practice to help plants survive a chill is to be sure they are well watered the day before a frost is forecast.  This is especially important for exposed container plants.  Moist soil holds the day’s heat better and hydrated tissue is less prone to frost injury.

Harvesting potatoes and onions isn’t driven by the danger of frosts and can be done more casually.  It is important for storage to “cure” them both for a couple weeks before putting them into storage.  Do not wash them, just brush off loose soil and lay out in a shaded, well-ventilated area, and cover with a light blocking cloth (not plastic). I use old burlap bags.  It is important that the outer skins are very dry to prevent soil borne fungi from causing rot in storage.  A good online reference for crop storage is available from Vermont’s own Gardener’s Supply Company.

Planting in late September   Some salad greens can still be planted, although they will germinate and grow very slowly.  Be sure to keep them well watered if it doesn’t rain.  Again, if you haven’t grown garlic before, this should be the year you start.  Local garden centers are selling “seed garlic” and a very good local source for seed garlic is Caravan Gardens on Rte. 103 in Cuttingsville (farmstand open Wednesdays and Saturdays).  Supermarket garlic is often treated with bleach and a chemical to retard growth so isn’t recommended for planting.  Another reason to grow your own!

Soil Fertility    Fall is the best time to begin soil improvements for next year. 

Step 1: do a basic soil test to learn the nutritional status of your soil.  Once you know about your soil pH, chemistry, etc. then you will know what additives will be most effective.  Do not assume that adding some lime and fertilizer will work; it could be counter-productive and wasteful.  I don’t recommend using the inexpensive little soil test kits or electronic meters sold in stores.  Soil testing is best done by a soil lab because their methods are more accurate, and they provide specific recommendations for the crops you want to grow. 

The University of Vermont testing lab offers a basic garden/lawn soil analysis for just $15 and includes pH, macro-nutrients, and other characteristics.  You may use their kits available in many garden centers or simply download their order form and instructions HERE.  You will need to send them about ½ cup of dried soil in a sealed plastic bag along with the completed order form.  Results will come back by mail or by email within 1-2 weeks and provide recommendations for what and how much to apply.  Please follow their instructions for How to Collect a Soil Sample, very important.

Step 2:  Soils in New England tend to be acidic (we have acid rain!) and usually benefit from the application of agricultural limestone or wood ash.  After you have the results of your soil test (step 1, above) you will know whether lime is called for, or not.  Soil pH refers to the acidity of the soil.  A pH of 7.0 is neutral, above 7.0 is alkaline, and below 7.0 is acidic.  This is important because if the pH is too low or too high the plant can’t get the nutrients that are in the soil.  Most plants do best in a slightly acidic soil, between 6.2 and 6.5.  A common sign of acidic soil (low pH) is leaf “chlorosis” or yellowing, an indication that lime should be added.

Fall is the best time to apply limestone to gardens and lawns because the effect on soil pH will take several months.  Lime applied now with be well incorporated into the soil and have raised the pH by spring planting time.

Do not assume lime will always help; there two cases in which lime applications will have poor results:  1) the soil pH is already above 6.5 and raising it higher will reduce the availability of nutrients to your plants.  2) The plants that you are growing prefer an acidic soil with a pH below 5.5.  This includes blueberries, raspberries, rhododendrons, azaleas, holly, and most potatoes.

Step 3:  Apply fertilizer, as called for by your soil test results.  As an organic gardener I strongly favor the regular application of compost to garden soil.  We make our own compost but you can also buy compost at most garden centers. Compost provides rich organic matter, beneficial microbes, good amounts of phosphate and potassium.  Nitrogen is usually low in compost but can be supplemented with animal manures (composted chicken or cow manure is best), green manures (legumes such as beans, peas, & clover), alfalfa meal, and organic granular fertilizers.  Compost also acts as a great stabilizer of pH and will keep your soil acidity in the desirable range. 

Compost applied in the fall will get naturally worked into the soil over winter and spring, making your soil rich and ready for the new season. If you are planting fall bulbs or garlic, I suggest putting a little (1 tsp) phosphate (bone meal or rock phosphate) in the bottom of each hole to support strong root growth.  Fill the hole with soil and cover with an inch of compost.

Pest Alerts:  Aphids flourish in the cool fall weather.  Watch your fall broccoli, Brussel sprouts, and kale.  Treat with insecticidal soap.  House plants destined to move inside should be sprayed with the garden hose to wash off adult aphids before treating at least twice, one week apart, with insecticidal soap to eliminate the young aphids.  These tiny beasts have a remarkable ability to reproduce because the females are born pregnant! 

Weeds… Don’t stop weeding yet!  Weeds are now producing their seeds for next year’s generation, and several generations after that.  Do not allow weeds to go to seed in your garden.

Remember to compost your food and yard wastes for the best garden fertilizer.  Here’s a short video to help you get your own compost started.

What did you learn in your garden this year?  Got questions?  Suggestions? Leave a message in the Comments below.