The Fall Vegetable Garden – What to Plant in August & September

August 7, 2025|The Rusted Garden|,

(Still Editing) August is a great time to direct seed your fall vegetable garden. My garden is in Maryland and the typical first frost date is the end of October or the beginning of November. The warm soil accelerates germination and early growth. However, the high heat of summer can inhibit germination for some seeds and high soil temperatures can kill off newly germinated seeds. Here are 10 tips to help you with planting cool crops in the heat of August for an amazing fall garden.

How you use these tips is based on the temperatures of your garden in August. In some cases, you may need to plant sooner if you have a shorter fall growing season. If you are in a warmer area, you may need to plant toward the end of August or the beginning of September. I recommend experimenting with different planting times and taking notes. You can adjust as needed, year to year, based on the outcomes.

Most cool crops can take a light frost and sometimes even heavier prolong freezes. Keep in mind August planted cool crops will germinate more quickly and grow more quickly. They often mature, for harvesting, at the lower end of the Days to Maturity guide.

Generally speaking, you can decide if you have enough time for a crop to fully mature by taking the lower end of Days to Maturity guide and adding 10-14 days to it. The total number of days needed for full growth should be completed before heavy prolong freezes show up in your garden.  A freeze of concern is one that damages the stem and roots just below the surface of the ground by freezing the ground. A frost typically impacts leaves and freezes impact the soil.

10 Tips for Growing a Fall Vegetable Garden Planted in August

1. Choose Cool-Weather Crops
Select vegetables that thrive in cooler temperatures and mature quickly. Cool crops can often take frosts. August is a great time to plant lettuce, spinach, radishes, turnips, kale, broccoli, beets, carrots, and arugula. Other crops for the fall garden can be found in the table.

2. Know Your First Frost Date
Find out the average first frost date for your region. Count backward from this date to ensure your crops have enough time to reach maturity before frost sets in. Add 10-14 days to the maturity date to ensure a period of harvesting before a heavy freeze sets in.

3. Take Advantage of Warm Soil
August soil is still warm, promoting fast seed germination and strong early growth. This helps crops establish quickly before temperatures drop. They grow faster and slow down growth as the cool temperatures arrive. Warm to cool soil changes allows for quick growth.

4. Water Regularly and Consistently
August heat can dry out the soil quickly. Water every other day. especially during seed germination and early growth. Avoid letting the soil completely dry out. The hot August sun can bake the soil. Water more often than you might think is needed.

5. Use Shade Cloth if Needed
In hot climates, protect tender seedlings from harsh sunlight by using shade cloth or light row covers until cooler weather arrives. Shade cloth help cool the soil and can help with germination for certain seeds. The sun can raise upper soil temperature to well over 100 F or 37.8 C. Prolonged high temps can cause damage.

6. Add Compost Before Planting or Use a Water-Soluble Fertilizer
Replenish soil nutrients by mixing in compost if it is available. This may not be the case and you can water in your plants with any organic water-soluble fertilizer that has N, P, and K represented. Compost and leaves can be placed on the surface of the soil when plants are larger for addition nutrients come the middle of the fall.

7. Use Row Covers for Pest Control/Sprays & Dusts
Fall pests such as cabbage worms, whiteflies, and flea beetles may still be active. Use what works best in your garden to prevent these pests from causing damage. As the cool weather arrives, many pests depart the garden.

8. Succession Plant for Continuous Harvest
Stagger plantings of quick-growing crops like lettuce, radishes, or spinach every 1–2 weeks after germination, through early September for a longer harvest season. This way you aren’t getting a dozen heads of lettuces or 200 radishes at once. In some garden you can plant these crops through October.

9. Watch the Daylight Hours
Shorter days in fall mean slower plant growth. Planting in August allows the plants to get plenty of light to establish and grow quickly. This helps crops like broccoli, cauliflower, and Brussels sprouts to grow full mature heads.

10. Be Ready to Protect Against ‘Heavy’ Frost
Keep row covers, frost blankets, or old sheets handy to protect crops from early heavy prolonged frosts. Different cool crops have different tolerance to freezing, so take notes as you grow and adjust what and when you plant each year.

Crop NameDays to MaturityPlant Spacing (in/cm)Germination Time
Arugula30–454–6 in / 10–15 cm5–7
Beets55–702–4 in / 5–10 cm5–10
Bok Choy45–606–12 in / 15–30 cm7–10
Broccoli60–10018–24 in / 45–60 cm5–10
Brussels Sprouts90–12018–24 in / 45–60 cm5–10
Cabbage70–10012–18 in / 30–45 cm4–10
Carrots60–802–3 in / 5–8 cm10–21
Cauliflower60–10018–24 in / 45–60 cm5–10
Celery85–1206–8 in / 15–20 cm14–21
Chinese Cabbage60–8012–18 in / 30–45 cm7–10
Collards60–8018–24 in / 45–60 cm5–10
Endive75–906–8 in / 15–20 cm7–10
Kale55–7512–18 in / 30–45 cm5–10
Kohlrabi50–606–8 in / 15–20 cm5–10
Leeks90–1204–6 in / 10–15 cm7–14
Lettuce (Leaf)40–554–6 in / 10–15 cm2–7
Mustard Greens30–506–8 in / 15–20 cm4–7
Napa Cabbage70–9012–18 in / 30–45 cm5–10
Onions (Green)60–802–4 in / 5–10 cm7–10
Parsnips100–1203–4 in / 8–10 cm14–21
Peas (Snow or Snap)55–702–4 in / 5–10 cm7–14
Radishes25–401–2 in / 2.5–5 cm3–7
Rutabaga90–1106–8 in / 15–20 cm7–10
Spinach40–504–6 in / 10–15 cm5–10
Turnips40–602–4 in / 5–10 cm4–8