Garden & Greenhouse

Greenhouses

Using a Greenhouse to Start Flower and Vegetable Plants in March

Posted March 22nd, 2016 by Robin Nichols in

March is a good month to begin plants for your flower and vegetable gardens. Listed below are some of the more common flower and vegetable plants that can be started in March. They will be ready to transplant outside in April and May. Varieties can be easily started in 1204 packs or 3″– 4″ pots. Plants in packs should be thinned to one plant per cell. The larger you want your transplants to grow, the bigger the cell or pot should be. If your germination space is small, you can start the seeds in smaller containers and transplant them into larger containers later.

The chart provides recommended, minimum size pots. Larger ones allow more room for roots, providing larger, healthier plants. Plants left in small containers too long will become root bound, decreasing growth vigor and production. Most tomatoes grown in larger pots will require staking.

The number of weeks recommended includes the period of germination at temperatures that are recommended by seed companies. To choose your planting date, decide when you want to sell or transplant your plant and begin germination the recommended number of weeks earlier. Seed companies can provide you with temperature and light/dark requirements as well. This information is often on the seed packages or provided in their catalogs.

Variety

Number of Weeks

Container Size

Number of Weeks

Container Size

Basil

6-8

1204 Pack

9-12

4” Pot

Broccoli

8

1204 Pack

Cabbage

8

1204 Pack

Eggplant

8

1204 Pack

9-12

4” Pot

Lettuce/Greens

3-4

1204 Pack

Onion

8

Open Pot or Flat

Pepper

10

1204 Pack

11-14

4” Pot

Tomato

6-8

1204 Pack

9-12

4-6” Pot

Dahlia

8

1204 Pack

9-12

4-6” Pot

Impatiens

8-9

1204 Pack

10-12

4” Pot

Marigold

7-8

1204 Pack

9-12

4” Pot

Nasturtium

4-5

1204 Pack

6-8

4” Pot

Petunia

10-12

1204 Pack

13-15

4” Pot

Sunflower

4-5

4” Pot

6-8

6” Pot

Zinnias

5-6

1204 Pack

7-9

4” Pot

Lettuce and most other greens are ready to transplant in 3 or 4 weeks, but they can be planted in March and transplanted into the garden in April in many locations. Broccoli and cabbage can also be transplanted before the last frost date for your area. Using temporary covers, leaves will be protected from frost and allowed to mature more quickly. Seedlings can also be transplanted into the greenhouse floor or beds and be raised without additional heat.

The number of weeks recommended for flowers in packs will provide a healthy green plant, except for short marigolds, impatiens and some petunias, which may start blooming in the packs. For blooms in containers the longer number of weeks are recommended.

Melon, cucumber, squash, and pumpkin plants grow quickly and need only 3-4 weeks before they can be transplanted into the garden. They should be started later, usually in April, and planted in May after the soil has become warm.

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