Greenhouse Gardening: Succession Planting

Greenhouse growing creates a sheltered atmosphere that allows gardening year round. Succession planting, or relay sowing, is the planting of a new and different crop immediately after one crop is reaped. Rotate each plant type to a new spot when succession sowing. Relay planting in a greenhouse maximizes your growing space and prolongs fruitful harvests.

Diligent effort and planning is involved when succession sowing in a greenhouse. Specific attention must be given to a plant's life cycle and growing habits and to which plants it can share a bed with and which plants can rotate in when the present plants mature. Garlic discourages aphids when planted as a companion for lettuce and peas. Pair mint or sage with cabbage, or include basil with the tomatoes. Read seed packages when deciding how you will organize the plants in your beds.

Each greenhouse is equipped differently. Some utilize ground space only; others have built-in shelves; still others have hooks for hanging pots, space to store gardening supplies and work benches. Some greenhouses are equipped with potting and bedding shelves. These are excellent for succession crops that grow with shallow roots, such as lettuces, kale, cabbage, herbs and green onions. Place sun loving, taller plants so they shade light-sensitive and shorter plants.

UMass Extension comments on, Root Diseases of Greenhouse Crops saying, "The two most common causes of root impairment of greenhouse crops are fertilizer toxicity and plant pathogenic fungi. In some cases, fertilizer toxicity predisposes plants to pathogenic fungi." Fill the planters with quality soil and well balanced compost. When using a soil testing kit you will not need to guess what nutrients your soil needs for the crop in succession.

Prepare planting beds three to four feet wide on the ground, or in raised boxes. This width is easiest to reach across from the path in your greenhouse. The lowest beds can be as long as your greenhouse can accommodate. Plant vegetables that need more room to grow, like squash, in these planters.

Maintaining your greenhouse temperatures ensures succession planting and growth through all four seasons. Air circulation in the summer allows outdoor plants to remain inside. A heating system in cold months prevents killing frosts.

Open the vents to create a cross breeze when the weather is warm. You may need to install exhaust fans to cool hotter days. When days are hot, open the doors at each end of the greenhouse, whitewash windows or use mesh fabric as shade. Open doors invite bees and ladybugs to visit plants that need pollinating in order to produce fruit.

Use heat pads for starter plants, a space heater and sun lamps when the weather turns cold and cloudy. Use a thermometer to keep an eye on your greenhouse weather and soil temperatures.

Imbalanced ventilation and heating conditions, over fertilizing and improper watering will encourage mold, root and stem rot. Sickly plant conditions invite unwanted pests, compounding succession gardening problems. Maintaining a healthy greenhouse atmosphere is worth concentrated effort when succession planting.

In Gardening Australia-Fact Sheet: Succession Planting, the ABC says, "Most crops only take two to three months to mature, fruit, and then exhaust themselves, so it's possible to get at least two or even more crops during that six month period."
Reap the rewards of your attentive care and hard work when it's time to harvest your bountiful produce. Pull tiring plants and throw them into the recycle heap. Mix fresh compost into the soil to replace the nutrients the new crop will need. Then in succession, start another crop by sowing seeds, or setting young starter plants.